Why I Want to be a Posthuman When I Grow Up
Nick Bostrom
Future of Humanity Institute
Faculty of Philosophy & James Martin 21st Century School
Oxford University
www.nickbostrom.com[Published in: Medical Enhancement and Posthumanity, eds. Bert Gordijn and Ruth Chadwick(Springer, 2008): pp. 107-137. First circulated: 2006]
I am apt to think, if we knew what it was to be an angel for one hour, we should return tothis world, though it were to sit on the brightest throne in it, with vastly more loathing
and reluctance than we would now descend into a loathsome dungeon or sepulchre. 1
Berkley (1685-1753)

Abstract
Extreme human enhancement could result in “posthuman” modes of being. After offering somedefinitions and conceptual clarification, I argue for two theses. First, some posthuman modes ofbeing would be very worthwhile. Second, it could be very good for human beings to become
posthuman.

1. Setting the stage
The term “posthuman” has been used in very different senses by different authors. 2 I am
sympathetic to the view that the word often causes more confusion than clarity, and that we might
be better off replacing it with some alternative vocabulary. However, as the purpose of this paper
is not to propose terminological reform but to argue for certain substantial normative theses(which one would naturally search for in the literature under the label “posthuman”), I will
instead attempt to achieve intelligibility by clarifying the meaning that I shall assign to the word.
Such terminological clarification is surely a minimum precondition for having a meaningful
discussion about whether it might be good for us to become posthuman.
I shall define a posthuman as a being that has at least one posthuman capacity. By a
posthuman capacity, I mean a general central capacity greatly exceeding the maximum attainable
by any current human being without recourse to new technological means. I will use generalcentral capacity to refer to the following:••

healthspan – the capacity to remain fully healthy, active, and productive, both mentallyand physicallycognition – general intellectual capacities, such as memory, deductive and analogicalreasoning, and attention, as well as special faculties such as the capacity to understandand appreciate music, humor, eroticism, narration, spirituality, mathematics, etc.

1

(Berkeley, Sampson et al. 1897), p. 172.
The definition used here follows in the spirit of (Bostrom 2003). A completely different concept of“posthuman” is used in e.g. (Hayles 1999).

2

1

•

emotion – the capacity to enjoy life and to respond with appropriate affect to life
situations and other people

In limiting my list of general central capacities to these three, I do not mean to imply that no othercapacity is of fundamental importance to human or posthuman beings. Nor do I claim that thethree capacities in the list are sharply distinct or independent. Aspects of emotion and cognition,for instance, clearly overlap. But this short list may give at least a rough idea of what I mean
when I speak of posthumans, adequate for present purposes.
In this paper, I will be advancing two main theses. The first is that some possible
posthuman modes of being would be very good. I emphasize that the claim is not that all possible
posthuman modes of being would be good. Just as some possible human modes of being are
wretched and horrible, so too are some of the posthuman possibilities. Yet it would be of interest
if we can show that there are some posthuman possibilities that would be very good. We mightthen, for example, specifically aim to realize those possibilities.
The second thesis is that it could be very good for us to become posthuman. It is possible
to think that it could be good to be posthuman without it being good for us to become posthuman.
This second thesis thus goes beyond the first. When I say “good for us”, I do not mean to insist
that for every single current human individual there is some posthuman mode of being such that it
would be good for that individual to become posthuman in that way. I confine myself to making aweaker claim that allows for exceptions. The claim is that for most current human beings, there
are possible posthuman modes of being such that it could be good for these humans to become
posthuman in one of those ways.
It might be worth locating the theses and arguments to be presented here within a broader
discourse about the desirability of posthumanity. Opponents of posthumanity argue that weshould not seek enhancements of a type that could make us, or our descendants, posthuman. We
can distinguish at least five different “levels” on which objections against posthumanity could belaunched:2

Table 1: Levels of objection to posthumanity
Level 0. “It can’t be done”
Objections based on empirical claims to the effect that it is, and will remain, impossible orinfeasible to create posthumans.
Level 1. “It is too difficult/costly”
Objections based on empirical claims that attempts to transform humans into posthumans, or tocreate new posthuman beings, would be too risky, or too expensive, or too psychologically
distracting. Concerns about medical side-effects fall into this category, as do concerns that
resources devoted to the requisite research and treatment would be taken away from more
important areas.
Level 2. “It would be too bad for society”
Objections based on empirical claims about social consequences that would follow from thesuccessful creation of posthuman beings, for example concerns about social inequality,
discrimination, or conflicts between humans and posthumans.
Level 3. “Posthuman lives would be worse than human lives”
Objections based on normative claims about the value of posthuman lives compared to human
lives.
Level 4. “We couldn’t benefit”
Objections based on agent-relative reasons against human beings transforming themselves into
posthuman beings or against humans bringing new posthuman beings into existence. Althoughposthuman lives might be as good as or better than human lives, it would be bad for us to become
posthuman or to create posthumans.

This paper focuses on levels 3 and 4. I am thus setting aside issues of feasibility, costs,
risks, side-effects, and social consequences. While those issues are obviously important when
considering what we have most reason to do all things considered, they will not be addressed
here.
Some further terminological specifications are in order. By a mode of being I mean a setof capacities and other general parameters of life. A posthuman mode of being is one that
includes at least one posthuman capacity.
I shall speak of the value of particular modes of being. One might hold that primaryvalue-bearers are some entities other than modes of being; e.g. mental states, subjective
experiences, activities, preference-satisfactions, achievements, or particular lives. Such views are
consistent with this paper. The position I seek to defend is consistent with a wide variety offormal and substantive theories of value. I shall speak of the value of modes of being for the sakeof simplicity and convenience, but in doing so I do not mean to express a commitment to any
particular controversial theory of value.
We might interpret “the values” of modes of beings as proxies for values that would be
realized by particular lives instantiating the mode of being in question. If we proceed in this way,
we create some indeterminacy. It is possible for a mode of being (and even more so for a class ofmodes of being) to be instantiated in a range of different possible lives, and for some of these
lives to be good and others to be bad. In such a case, how could one assign a value to the mode ofbeing itself?
Another way of expressing this concern is by saying that the value of instantiating aparticular mode of being is context-dependent. In one context, the value might be high; inanother, it might be negative. Nevertheless, it is useful to be able to speak of values of items otherthan those we accord basic intrinsic value. We might for example say that it is valuable to be in3

good health and to have some money. Yet neither having good health nor having some money isguaranteed to make a positive difference to the value of your life. There are contexts in which the
opposite is true. For instance, it could be the case that because you had some money you got
robbed and murdered, or that because you were always in rude health you lacked a particular(short, mild) disease experience that would have transformed your mediocre novel into an
immortal masterpiece. Even so, we can say that health and money are good things without
thereby implying that they are intrinsically valuable or that they add value in all possible contexts.
When we say that they are valuable we might merely mean that these things would normally
make a positive contribution to the value of your life; they would add value in a very wide rangeof plausible contexts. This mundane meaning is what I have in mind when I speak of modes ofbeing having a value: i.e., in a very wide range of plausible contexts, lives instantiating that modeof being would tend to contain that value. 3
A life might be good or bad because of its causal consequences for other people, or forthe contribution it makes to the overall value of a society or a world. But here I shall focus on thevalue that a life has for the person whose life it is: how good (or bad) it is for the subject to havethis life. The term “well-being” is often used in this sense. 4
When I speak of the value of a life here, I do not refer to the moral status of the person
whose life it is. It is a separate question what the moral status would be of human and posthumanbeings. We can assume for present purposes that human and posthuman persons would have thesame moral status. The value of a life refers, rather, to how well a life goes for its subject.
Different human lives go differently well, and in this sense their lives have different values. The
life of a person who dies from a painful illness at age 15 after having lived in extreme poverty
and social isolation is typically worse and has less value than that of a person who has an 80-yearlong life full of joy, creativity, worthwhile achievements, friendships, and love. Whatever
terminology we use to describe the difference, it is plain that the latter kind of life is more worth
having. One way to express this platitude is by saying that the latter life is more valuable than theformer. 5 This is consistent with assigning equal moral status to the two different persons whose
lives are being compared.
Some pairs of possible lives are so different that it is difficult – arguably impossible – tocompare their value. We can leave aside the question of whether, for every pair of possible lives,
it is true either than one is better than the other, or that they are equally good; that is, whether all
pairs of possible lives have commensurable value. We shall only assume that at least for somepairs of possible lives, one is definitely better than the other.
To supply our minds with a slightly more concrete image of what becoming posthumanmight be like, let us consider a vignette of how such a process could unfold.

3

Compare this take on “mundane values” with the notion of mid-level principles in applied ethics. The
principle of respecting patient autonomy is important in medical ethics. One might accept this if one holds
that respect for patient autonomy is an implication of some fundamental ethical principle. But equally, one
might accept patient autonomy as an important mid-level principle even if one merely holds that this is a
way of expressing a useful rule of thumb, a sound policy rule, or a derived ethical rule that is true in aworld like ours because of various empirical facts even though it is not necessarily true in all possible
worlds. For the role of mid-level principles in applied ethics, see e.g. (Beauchamp and Childress 2001).
4
I am thus not concerned here with global evaluations into which individuals’ well-being might enter as afactor, e.g. evaluations involving values of diversity, equality, or comparative fairness.
5
I do not assume that the value of a life, or well-being, supervenes on the mental experiences of a person,
nor that it supervenes on a thin time-slice of a person’s life. It could represent a wider and more global
evaluation of how well a person’s life is going.

42. Becoming posthumanLet us suppose that you were to develop into a being that has posthuman healthspan andposthuman cognitive and emotional capacities. At the early steps of this process, you enjoy yourenhanced capacities. You cherish your improved health: you feel stronger, more energetic, andmore balanced. Your skin looks younger and is more elastic. A minor ailment in your knee is
cured. You also discover a greater clarity of mind. You can concentrate on difficult material moreeasily and it begins making sense to you. You start seeing connections that eluded you before.
You are astounded to realize how many beliefs you had been holding without ever really thinking
about them or considering whether the evidence supports them. You can follow lines of thinking
and intricate argumentation farther without losing your foothold. Your mind is able to recall facts,
names, and concepts just when you need them. You are able to sprinkle your conversation withwitty remarks and poignant anecdotes. Your friends remark on how much more fun you are to bearound. Your experiences seem more vivid. When you listen to music you perceive layers ofstructure and a kind of musical logic to which you were previously oblivious; this gives you greatjoy. You continue to find the gossip magazines you used to read amusing, albeit in a different
way than before; but you discover that you can get more out of reading Proust and Nature. You
begin to treasure almost every moment of life; you go about your business with zest; and you feela deeper warmth and affection for those you love, but you can still be upset and even angry on
occasions where upset or anger is truly justified and constructive.
As you yourself are changing you may also begin to change the way you spend yourtime. Instead of spending four hours each day watching television, you may now prefer to play
the saxophone in a jazz band and to have fun working on your first novel. Instead of spending theweekends hanging out in the pub with your old buddies talking about football, you acquire newfriends with whom you can discuss things that now seem to you to be of greater significance thansport. Together with some of these new friends, you set up a local chapter of an international nonprofit to help draw attention to the plight of political prisoners.
By any reasonable criteria, your life improves as you take these initial steps towards
becoming posthuman. But thus far your capacities have improved only within the natural humanrange. You can still partake in human culture and find company to engage you in meaningfulconversation. Consider now a more advanced stage in the transformation process…
You have just celebrated your 170th birthday and you feel stronger than ever. Each day is
a joy. You have invented entirely new art forms, which exploit the new kinds of cognitive
capacities and sensibilities you have developed. You still listen to music – music that is to Mozart
what Mozart is to bad Muzak. You are communicating with your contemporaries using alanguage that has grown out of English over the past century and that has a vocabulary andexpressive power that enables you to share and discuss thoughts and feelings that unaugmented
humans could not even think or experience. You play a certain new kind of game which
combines VR-mediated artistic expression, dance, humor, interpersonal dynamics, and various
novel faculties and the emergent phenomena they make possible, and which is more fun thananything you ever did during the first hundred years of your existence. When you are playing thisgame with your friends, you feel how every fiber of your body and mind is stretched to its limit in
the most creative and imaginative way, and you are creating new realms of abstract and concrete
beauty that humans could never (concretely) dream of. You are always ready to feel with those
who suffer misfortunes, and to work hard to help them get back on their feet. You are also
involved in a large voluntary organization that works to reduce suffering of animals in theirnatural environment in ways that permit ecologies to continue to function in traditional ways; thisinvolves political efforts combined with advanced science and information processing services.
Things are getting better, but already each day is fantastic.
As we seek to peer farther into posthumanity, our ability to concretely imagine what it
might be like trails off. If, aside from extended healthspans, the essence of posthumanity is to be5able to have thoughts and experiences that we cannot readily think or experience with our current
capacities, then it is not surprising that our ability to imagine what posthuman life might be like isvery limited. Yet we can at least perceive the outlines of some of the nearer shores of
posthumanity, as we did in the imaginary scenario above. Hopefully such thought experiments
are already enough to give plausibility to the claim that becoming posthuman could be good forus.
In the next three sections we will look in a little more detail at each of the three generalcentral capacities that I listed in the introduction section. I hope to show that the claim that it
could be very good to be posthuman is not as radical as it might appear to some. In fact, we willfind that individuals and society already in some ways seem to be implicitly placing a very highvalue on posthuman capacities – or at least, there are strong and widely accepted tendencies
pointing that way. I therefore do not regard my claim as in any strong sense revisionary. On thecontrary, I believe that the denial of my claim would be strongly revisionary in that it would force
us to reject many commonly accepted ethical beliefs and approved behaviors. I see my position asa conservative extension of traditional ethics and values to accommodate the possibility of humanenhancement through technological means.

3. Healthspan
It seems to me fairly obvious why one might have reason to desire to become a posthuman in thesense of having a greatly enhanced capacity to stay alive and stay healthy. 6 I suspect that the
majority of humankind already has such a desire implicitly.
People seek to extend their healthspan, i.e. to remain healthy, active, and productive. Thisis one reason why we install air bags in cars. It may also explain why we go to the doctor when
we are sick, why higher salaries need to be paid to get workers to do physically dangerous work,
and why governments and charities give money to medical research. 7 Instances of individuals
sacrificing their lives for the sake of some other goal, whether suicide bombers, martyrs, or drug
addicts, attract our attention precisely because their behavior is unusual. Heroic rescue workers
who endanger their lives on a dangerous mission are admired because we assume that they are
putting at risk something that most people would be very reluctant to risk, their own survival.
For some three decades, economists have attempted to estimate individuals’ preferences
over mortality and morbidity risk in labor and product markets. While the tradeoff estimates varyconsiderably between studies, one recent meta-analysis puts the median value of the value of astatistical life for prime-aged workers to about $7 million in the United States. 8 A study by theEU’s Environment Directorates-General recommends the use of a value in the interval €0.9 to€3.5 million. 9 Recent studies by health economists indicate that improvements in the health statusof the U.S. population over the 20th century have made as large a contribution to raising thestandards of living as all other forms of consumption growth combined. 10 While the exact
numbers are debatable, there is little doubt that most people place a very high value on theircontinued existence in a healthy state.
Admittedly, a desire to extend one’s healthspan is not necessarily a desire to become
posthuman. To become posthuman by virtue of healthspan extension, one would need to achieve
6

Having such a capacity is compatible with also having the capacity to die at any desired age. One mightthus desire a capacity for greatly extended healthspan even if one doubts that one would wish to live formore than, say, 80 years. A posthuman healthspan capacity would give one the option of much longer andhealthier life, but one could at any point decide no longer to exercise the capacity.
7
Although on the last item, see (Hanson 2000) for an alternative view.
8(Viscusi and Aldy 2003).
9(Johansson 2002).
10(Murphy and Topel 2003; Nordhaus 2003).

6

the capacity for a healthspan that greatly exceeds the maximum attainable by any current humanbeing without recourse to new technological means. Since at least some human beings alreadymanage to remain quite healthy, active, and productive until the age of 70, one would need todesire that one’s healthspan were extended greatly beyond this age in order that it would count as
having a desire to become posthuman. 11
Many people will, if asked about how long they would wish their lives to be, name afigure between 85 and 90 years. 12 In many cases, no doubt, this is because they assume that a life
significantly longer than that would be marred by deteriorating health – a factor from which wemust abstract when considering the desirability of healthspan extension. People’s statedwillingness to pay to extend their life by a certain amount does in fact depend strongly on thehealth status and quality of that extra life. 13 Since life beyond 85 is very often beset bydeteriorating health, it is possible that this figure substantially underestimates how long mostpeople would wish to live if they could be guaranteed perfect health.
It is also possible that a stated preference for a certain lifespan is hypocritical. Estimates
based on revealed preferences in actual market choices, such as fatality risk premiums in labormarkets or willingness to pay for health care and other forms of fatality risk reduction might bemore reliable. It would be interesting to know what fraction of those who claim to have no desire
for healthspan extension would change their tune if they were ever actually handed a pill thatwould reliably achieve this effect. My conjecture would be that when presented with a real-world
choice, most would choose the path of prolonged life, health, and youthful vigor over the default
route of aging, disease, and death.
One survey asked: “Based on your own expectations of what old age is like, if it were up
to you, how long would you personally like to live – to what age?” Only 27% of respondents said
they would like to live to 100 or older. 14 A later question in the same survey asked: “Imagine you
could live to 100 or older, but you’d have to be very careful about your diet, exercise regularly,
not smoke, avoid alcohol, and avoid stress. Would it be worth it, or not?” To this, 64% answeredin the affirmative! Why should more people want to live beyond 100 when restrictions on activity
are imposed? Is it because it frames the question more as if it were a real practical choice rather
than as an idle mind game? Perhaps when the question is framed as a mind game, respondents
tend to answer in ways which they believe expresses culturally approved attitudes, or which they
think signal socially desirable personal traits (such as having “come to terms” with one’s own
mortality), while this tendency is diminished when the framing suggests a practical choice withreal consequences. We do not know for sure, but this kind of anomaly suggests that we should nottake people’s stated “preferences” about how long they would wish to live too seriously, and thatrevealed preferences might be a more reliable index of their guiding values.
It is also worth noting that only a small fraction of us commit suicide, suggesting that ourdesire to live is almost always stronger than our desire to die. 15 Our desire to live, conditional on
our being able to enjoy full health, is even stronger. This presumption in favor of life is in fact sostrong that if somebody wishes to die soon, even though they are seemingly fully healthy, with along remaining healthy life expectancy, and if their external circumstances in life are notcatastrophically wretched, we would often tend suspect that they might be suffering from11

At least one human, Jeanne Calment, lived to 122. But although she remained in relatively fair health
until close to her death, she clearly suffered substantial decline in her physical (and presumably mental)
vigor compared to when she was in her twenties. She did not retain the capacity to be fully healthy, active,
and productive for 122 years.
12(Cohen and Langer 2005).
13(Johnson, Desvousges et al. 1998).
14(Cohen and Langer 2005).
15
For some, the reluctance to commit suicide might reflect a desire not to kill oneself rather than a desire
not to die, or alternatively a fear of death rather than an authentic preference not to die.

7

depression or other mental pathology. Suicidal ideation is listed as a diagnostic symptom of
depression by the American Psychiatric Association. 16
Even if a stated preference against healthspan extension were sincere, we would need toquestion how well-considered and informed it is. It is of relevance that those who know mostabout the situation and are most directly affected by the choice, namely the elderly, usually preferlife to death. They usually do so when their health is poor, and overwhelmingly choose life when
their health is at least fair. Now one can argue that a mentally intact 90-year-old is in a better
position to judge how their life would be affected by living for another year than she was when
she was 20, or 40. If most healthy and mentally intact 90-year-olds prefer to live for another year
(at least if they could be guaranteed that this extra year would be one of full health and vigor),this would be evidence against the claim that it would be better for these people that their lives
end at 90. 17 Similarly, of course, for people of even older age.
One can compare this situation with the different case of somebody becoming paraplegic.
Many able-bodied people believe that their lives would not be worth living if they became
paraplegic. They claim that they would prefer to die rather than continuing life in a paraplegicstate. Most people who have actually become paraplegic, however, find that their lives are worth
living. 18 People who are paraplegic are typically better judges of whether paraplegic lives areworth continuing than are people who have never experienced what it is like to be paraplegic.
Similarly, people who are 90 years old are in a better position to judge whether their lives areworth continuing than are younger people (including themselves at any earlier point in theirlives). 19
One study assessed the will to live among 414 hospitalized patients aged 80 to 98 years,
presumably representing the frailer end of the distribution of the “old old”. 40.8% of respondents
were unwilling to exchange any time in their current state of health for a shorter life in excellent
health, and 27.8% were willing to give up at most 1 month of 12 in return for excellent health. 20(Patients who were still alive one year later were even less inclined to give up life for better
health, but with continued large individual variations in preferences.) The study also found thatpatients were willing to trade significantly less time for a healthy life than their surrogatesassumed they would.
Research shows that life-satisfaction remains relatively stable into old age. One survey of
60,000 adults from 40 nations discovered a slight upward trend in life-satisfaction from the 20s to
the 80s in age. 21 Life satisfaction showed this upward trend even though there was some loss of
positive affect. Perhaps life-satisfaction would be even higher if positive affect were improved (apossibility we shall discuss in a later section). Another study, using a cross-sectional sample (agerange 70-103 years), found that controlling for functional health constraints reversed the directionof the relationship between age and positive affect and produced a negative association between

16

DSM-IV (American Psychiatric Association. 2000).
This is a kind of Millian best-judge argument. However, if fear of death were irrational, one could argue
that people who are closer to death are on average worse judges of the value for them of an extra year oflife, because their judgments would tend to be more affected by irrational fear.
18
This basic result is reflected in many chronic disease conditions (Ubel, Loewenstein et al. 2003). The
discrepancy of attitudes seems to be due to non-patient’s failure to realize the extent to which patients
psychologically adapt to their condition (Damschroder, Zikmund-Fisher et al. 2005).
19
The analogy with paraplegia is imperfect in at least one respect: when the issue is healthspan extension,
we are considering whether it would be worth living an extended life in perfect health and vigor. If
anything, this discrepancy strengthens the conclusion, since it is more worth continuing living in perfect
health than in poor health, not less worth it.
20(Tsevat, Dawson et al. 1998). See also (McShine, Lesser et al. 2000). For a methodological critique, see(Arnesen and Norheim 2003).
21(Diener and Suh 1998).
178age and negative affect. 22 These findings suggest that some dimensions of subjective well-being,such as life-satisfaction, do not decline with age but might actually increase somewhat, and thatthe decline in another dimension of subjective well-being (positive affect) is not due to aging per
se but to health constraints.
Most people reveal through their behavior that they desire continued life and health, 23
and most of those who are in the best position to judge the value of continued healthy life, at any
age, judge that it is worth having. This constitutes prima facie support for the claim that extended
life is worth having even when it is not fully healthy. The fact that this holds true at all currently
realized ages suggests that it is not a strongly revisionary view to hold that it could be good formany people to become posthuman through healthspan extension. Such a view might already be
implicitly endorsed by many.

4. Cognition
People also seem to be keen on improving cognition. Who wouldn’t want to remember names andfaces better, to be able more quickly to grasp difficult abstract ideas, and to be able to “seeconnections” better? Who would seriously object to being able to appreciate music at a deeper
level? The value of optimal cognitive functioning is so obvious that to elaborate the point may beunnecessary. 24
This verdict is reflected in the vast resources that society allocates to education, which
often explicitly aims not only to impart specific items of knowledge but also to improve general
reasoning abilities, study skills, critical thinking, and problem solving capacity. 25 Many people
are also keen to develop various particular talents that they may happen to have, for example
musical or mathematical, or to develop other specific faculties such as aesthetic appreciation,
narration, humor, eroticism, spirituality etc. We also reveal our desire for improving our cognitive
functioning when take a cup of coffee to increase our alertness or when we regret our failure toobtain a full night’s sleep because of the detrimental effects on our intellectual performance.
Again, the fact that there is a common desire for cognitive improvement does not imply
that there is a common desire for becoming posthuman. To want to become posthuman throughcognitive improvement, one would have to want a great deal of cognitive improvement. It is
logically possible that each person would only want to become slightly more intelligent (ormusical, or humorous) than he or she currently is and would not want any very large gain. I willoffer two considerations regarding this possibility.
First, it seems to me (based on anecdotal evidence and personal observations) that people
who are already endowed with above-average cognitive capacities are at least as eager, and, fromwhat I can tell, actually more eager to obtain further improvements in these capacities than arepeople who are less talented in these regards. For instance, someone who is musically gifted islikely to spend more time and effort trying to further develop her musical capacities than issomebody who lacks a musical ear; and likewise for other kinds of cognitive gifts.
This phenomenon may in part reflect the external rewards that often accrue to those who
excel in some particular domain. An extremely gifted musician might reap greater rewards interms of money and esteem from a slight further improvement in her musicality than would
22(Kunzmann, Little et al. 2000).
This is fully consistent with the fact that many people knowingly engage in risky behaviors such as
smoking. This might simply mean that they are unable to quit smoking, or that they desire the pleasure ofsmoking more than they desire a longer healthier life. It does not imply that they do not desire longer
healthier life.
24
One might even argue that a desire for cognitive improvement is a constitutive element of humanrationality, but I will not explore that hypothesis here.
25
U.S. public expenditure on education in 2003 was 5.7% of its GDP (World Bank. 2003).
23

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somebody who is not musically gifted to begin with. That is, the difference in external rewards issometimes greater for somebody who goes from very high capacity to outstandingly highcapacity than it is for somebody who goes from average capacity to moderately high capacity.
However, I would speculate that such differences in external rewards are only part of the
explanation and that people who have high cognitive capacities are usually also more likely (or atleast no less likely) to desire further increases in those capacities than are people of lower
cognitive capacities even when only the intrinsic benefits of capacities are considered. Thus, if we
imagine a group of people placed in solitary confinement for the remainder of their lives, but withaccess to books, musical instruments, paints and canvasses, and other prerequisites for the
exercise of capacities, I would hypothesize that those with the highest pre-existing capacity in agiven domain would be more likely (or at least not less likely) to work hard to further develop
their capacities in that domain, for the sake of the intrinsic benefits that the possession andexercise of those capacities bestow, than would those with lower pre-existing capacities in thesame domain. 26 While $100 brings vastly less utility to a millionaire than to a pauper, themarginal utility of improved cognitive capacities does not seem to exhibit a similar decline.
These considerations suggest that there are continuing returns in the “intrinsic” (in thesense of non-instrumental, non-positional) utility of gains in cognitive capacities, at least within
the range of capacity that we find instantiated within the current human population. 27 It would be
implausible to suppose that the current range of human capacity, in all domains, is such that while
increments of capacity within this range are intrinsically rewarding, yet any further increases
outside the current human range would lack intrinsic value. Again, we have a prima facie reason
for concluding that enhancement of cognitive capacity to the highest current human level, andprobably beyond that, perhaps up to and including the posthuman level, would be intrinsicallydesirable for the enhanced individuals. We get this conclusion if we assume that those who have acertain high capacity are generally better judges of the value of having that capacity or of afurther increment of that capacity than are those who do not possess the capacity in question to
the same degree.

4. Emotion
It is straightforward to determine what would count as an enhancement of healthspan. We have aclear enough idea of what it means to be healthy, active, and productive, and the difference
between this state and that of being sick, incapacitated, or dead. An enhancement of healthspan issimply an intervention that prolongs the duration of the former state. It is more difficult to define
precisely what would count as a cognitive enhancement because the measure of cognitive
functioning is more multifaceted, various cognitive capacities can interact in complex ways, and
it is a more normatively complex problem to determine what combinations of particular cognitivecompetences are of value in different kinds of environments. For instance, it is not obvious what
degree of tendency to forget certain kinds of facts and experiences is desirable. The answer might
depend on a host of contextual factors. Nevertheless, we do have some general idea of how wemight value various increments or decrements in many aspects of our cognitive functioning – a26Complication: if high capacity were solely a result from having spent a lot of effort in developing thatcapacity, then the people with high capacity in some domain might be precisely those that started out
having an unusually strong desire for having a strong capacity in that domain. It would then not be
surprising that those with high capacity would have the strongest desire for further increases in capacity.
Their stronger desire for higher capacity might then not be the result of more information and better
acquaintance with what is at stake, but might instead simply reflect a prior inclination.
27
It would be more difficult to determine whether the marginal intrinsic utility of gains in capacity are
constant, or diminishing, or increasing at higher levels of capacity, and if so by what amount.

10

sufficiently clear idea, I suggest, to make it intelligible without much explanation what one mightmean by phrases like “enhancing musical ability”, “enhancing abstract reasoning ability” etc.
It is considerably more difficult to characterize what would count as emotional
enhancement. Some instances are relatively straightforward. Most would readily agree that
helping a person who suffers from persistent suicidal depression as the result of a simple
neurochemical imbalance so that she once again becomes capable of enjoyment and of taking aninterest in life would be to help her improve her emotional capacities. Yet beyond cases involving
therapeutic interventions to cure evident psychopathology it is less clear what would count as anenhancement. One’s assessment of such cases often depends sensitively on the exact nature of
one’s normative beliefs about different kinds of possible emotional constitutions andpersonalities.
It is correspondingly difficult to say what would constitute a “posthuman” level of
emotional capacity. Nevertheless, people often do strive to improve their emotional capacities andfunctionings. We may seek to reduce feelings of hate, contempt, or aggression when we
consciously recognize that these feelings are prejudiced or unconstructive. We may take up
meditation or physical exercise to achieve greater calm and composure. We may train ourselves
to respond more sensitively and empathetically to those we deem deserving of our trust andaffection. We may try to overcome fears and phobias that we recognize as irrational, or we may
wrestle with appetites that threaten to distract us from what we value more. Many of us expend
life-long effort to educate and ennoble our sentiments, to build our character, and to try to become
better people. Through these strivings, we seek to achieve goals involving modifying andimproving our emotional capacities.
An appropriate conception of emotional capacity would be one that incorporates orreflects these kinds of goal, while allowing perhaps for there being a wide range of different waysof instantiating “high emotional capacity”, that is to say, many different possible “characters” or
combinations of propensities for feeling and reacting that could each count as excellent in its own
way. If this is admitted, then we could make sense of emotional enhancement in a wide range ofcontexts, as being that which makes our emotional characters more excellent. A posthumanemotional capacity would be one which is much more excellent than that which any current
human could achieve unaided by new technology.
One might perhaps question whether there are possible emotional capacities that would
be much more excellent than those attainable now. Conceivably, there might be a maximum of
possible excellence of emotional capacity, and those people who currently have the bestemotional capacities might approach so closely to this ideal that there is not enough potential left
for improvement to leave room for a posthuman realm of emotional capacity. I doubt this,because aside from the potential for fine-tuning and balancing the various emotional sensibilities
we already have, I think there might also be entirely new psychological states and emotions that
our species has not evolved the neurological machinery to experience, and some of thesesensibilities might be ones we would recognize as extremely valuable if we became acquainted
with them.
It is difficult intuitively to understand what such novel emotions and mental states might
be like. This is unsurprising, since by assumption we currently lack the required neurologicalbases. It might help to consider a parallel case from within the normal range of humanexperience. The experience of romantic love is something that many of us place a high value on.
Yet it is notoriously difficult for a child or a prepubescent teenager to comprehend the meaning ofromantic love or why adults should make so much fuss about this experience. Perhaps we are all
currently in the situation of children relative to the emotions, passions, and mental states that
posthuman beings could experience. We may have no idea of what we are missing out on until we
attain posthuman emotional capacities.
One dimension of emotional capacity that we can imagine enhanced is subjective wellbeing and its various flavors: joy, comfort, sensual pleasures, fun, positive interest and11excitement. Hedonists claim that pleasure is the only intrinsic good, but one need not be ahedonist to appreciate pleasure as one important component of the good. The difference between
a bleak, cold, horrid painful world and one that is teeming with fun and exciting opportunities,
full of delightful quirks and lovely sensations, is often simply a difference in the hedonic tone ofthe observer. Much depends on that one parameter.
It is an interesting question how much subjective well-being could be enhanced without
sacrificing other capacities that we may value. For human beings as we are currently constituted,
there is perhaps an upper limit to the degree of subjective well-being that we can experience
without succumbing to mania or some other mental unbalance that would prevent us from fully
engaging with the world if the state were indefinitely prolonged. But it might be possible fordifferently constituted minds to have experiences more blissful than those that humans arecapable of without thereby impairing their ability to respond adequately to their surroundings.
Maybe for such beings, gradients of pleasure could play a role analogous to that which the scaleranging between pleasure and pain has for us. 28 When thinking the possibility of posthumanly
happy beings, and their psychological properties, one must abstract from contingent features of
the human psyche. An experience that would consume us might perhaps be merely “spicy” to a
posthuman mind.
It is not necessary here to take a firm stand on whether posthuman levels of pleasure arepossible, or even on whether posthuman emotional capacities more generally are possible. But wecan be confident that, at least, there is vast scope for improvements for most of individuals inthese dimensions because even within the range instantiated by currently exiting humans, there
are levels of emotional capacities and degrees of subjective well-being that, for most of us, arepractically unattainable to the point of exceeding our dreams. The fact that such improvements
are eagerly sought by many suggests that if posthuman levels were possible, they too would beviewed as highly attractive. 29

5. Structure of the argument, and further supporting reasons
It might be useful to pause briefly to reflect on the structure of the argument presented so far. I
began by listing three general central capacities (healthspan, cognition, and emotion), and I
defined a posthuman being as one who has at least one of these capacities in a degree unattainable
by any current human being unaided by new technology.
I offered some plausibility arguments suggesting that it could be highly desirable to have
posthuman levels of these capacities. I did this partly by clarifying what having the capacities
would encompass and by explaining how some possible objections would not apply because they
rely on a misunderstanding of what is proposed. Furthermore, I tried to show that for each of thethree capacities we find that many individuals actually desire to develop the capacities to higher
levels and often undertake great effort and expense to achieve these aims. This desire is also
reflected in social spending priorities, which devote significant resources to e.g. healthspanextending medicine and cognition-improving education. Significantly, at least in the cases ofhealthspan extension and cognitive improvement, the persons best placed to judge the value anddesirability of incremental improvements at the high end of the contemporary human capacity
distribution seem to be especially likely to affirm the desirability of such additional
improvements of capacity. For many cognitive faculties, it appears that the marginal utility of
improvements increases with capacity levels. This suggests that improvements beyond the28(Pearce 2004).
The quest for subjective well-being, in particular, seems to be a powerful motivator for billions of people
even though arguably none of the various means that have been attempted in this quest has yet proved very
efficacious in securing the goal (Brickman and Campbell 1971).
29

12

current human range would also viewed as desirable when evaluated by beings in a better
position to judge than we currently are.
That people desire X does not imply that X is desirable. Nor does the fact that people find
X desirable, even when this judgment is shared among those who are in the best position to judge
the desirability of X, prove that X is desirable or valuable. Even if one were to assume someversion of a dispositional theory of value, it does not follow from these premises that X isvaluable. A dispositional theory of value might assert something like the following:
X is valuable for A if and only if A would value X if A were perfectly rational, perfectly
well-informed, and perfectly acquainted with X. 30
The people currently best placed to judge the desirability for an individual of enhancement of her
general central capacities are neither perfectly rational, nor perfectly well-informed, nor perfectly
acquainted with the full meaning of such enhancements. If these people were more rational or
obtained more information or became better acquainted with the enhancements in question, theywould perhaps no longer value the enhancements. Even if everybody judged becoming
posthuman as desirable, it is a logical possibility that becoming posthuman is not valuable, evengiven a theory of value that defines value in terms of valuing-dispositions.
The argument presented in the preceding sections is not meant to be deductive. Its
ambition is more modest: to remind us of the plausibility of the view that (1) enhancements along
the three dimensions discussed are possible in principle and of significant potential intrinsic
value, and (2) enhancements along these dimensions large enough to produce posthuman beings
could have very great intrinsic value. This argument is defeasible. One way in which it could be
defeated would be by pointing to further information, rational reasoning, or forms ofacquaintance, not accounted for by current opinion, and which would change current opinion if itwere incorporated. Critics could for example try to point to some reasoning mistake that very oldpeople commit when they judge that it would be good for them to live another year in perfect
health. However, I think the considerations I have pointed to provide prima facie evidence for myconclusions.
There are other routes by which one could reach the position that I have advocated, which
supports the above arguments. For instance, one might introspect one’s own mind to determine
whether being able to continue to live in good health longer, being able better to understand theworld and other people, or being able more fully to enjoy life and to react with appropriate affectto life events would seem like worthwhile goals for oneself if they were obtainable. 31
Alternatively, one might examine whether having these capacities to an enhanced or evenposthuman degree could enable one to realize states and life paths that would have great value
according to one’s favorite theory of value. (To me, both these tests deliver affirmative verdictson (1) and (2).)
Yet another route to making the foregoing conclusions plausible is by considering ourcurrent ignorance and the vastness of the as-yet unexplored terrain. Let SH be the “space” ofpossible modes of being that could be instantiated by someone with current human capacities. Let
SP be the space of possible modes of being that could be instantiated by someone with posthumancapacities. In an intuitive sense, SP is enormously much larger than SH. There is a larger range ofpossible life courses that could be lived out during a posthuman lifespan than during a human
lifespan. There are more thoughts that could be thought with posthuman cognitive capacities thanwith human capacities (and more musical structures that could be created and appreciated withposthuman musical capacities etc.). There are more mental states and emotions that could be
experienced with posthuman emotional faculties than with human ones. So why, apart from a lack30
31

See e.g. (Lewis 1989).
See e.g. (Bostrom 2005).

13

of imagination, should anybody suppose that the SH already contains all the most valuable andworthwhile modes of being?
An analogy: For as long as anybody remembers, a tribe has lived in a certain deep andnarrow valley. They rarely think of what lies outside their village, and on the few occasions when
they do, they think of it only as a mythical realm. One day a sage who has been living apart fromthe rest, on the mountainside, comes down to the village. He explains that he has climbed to the
top of the mountain ridge and from there he could see the terrain stretching far away, all the way
to the horizon. He saw plains, lakes, forests, winding rivers, mountains, and the sea. Would it not
be reasonable, he says, in lieu of further exploration, to suppose that this vast space is likely to behome to natural resources of enormous value? – Similarly, the sheer size and diversity of SP is in
itself a prima facie reason for thinking that it is likely to contain some very great values. 32

6. Personal identity
Supposing the previous sections have succeeded in making it plausible that being a posthuman
could be good, we can now turn to a further question: whether becoming posthuman could begood for us. It may be good to be Joseph Haydn. Let us suppose that Joseph Haydn had a better
life than Joe Bloggs so that in some sense it is better to be Haydn and living the life that Haydn
lived than to be Bloggs and living Bloggs’ life. We may further suppose that this is so from
Bloggs’ evaluative standpoint. Bloggs might recognize that on all the objective criteria which hethinks makes for a better mode of being and a better life, Haydn’s mode of being and life are
better than his own. Yet it does not follow that it would be good for Bloggs to “become” Haydn(or to become some kind of future equivalent of Haydn) or to live Haydn’s life (or a Haydn-likelife). There are several possible reasons for this which we need to examine.
First, it might not be possible for Bloggs to become Haydn without ceasing to be Bloggs.
While we can imagine a thought experiment in which Bloggs’ body and mind are graduallytransformed into those of Haydn (or of a Haydn-equivalent), it is not at all clear that personal
identity could be preserved through such a transformation. If Bloggs’ personal identity isessentially constituted by some core set of psychological features such as his memories anddispositions, then, since Haydn does not have these features, the person Bloggs could not becomea Haydn-equivalent. Supposing that Bloggs has a life that is worth living, any transformation thatcauses the person Bloggs to cease to exist might be bad for Bloggs, including one that transforms
him into Haydn.
Could a current human become posthuman while remaining the same person, or is thecase like the one of Bloggs becoming Haydn, the person Bloggs necessarily ceasing to exist in theprocess? The case of becoming posthuman is different in an important respect. Bloggs would
have to lose all the psychological characteristics that made him person Bloggs in order to become
Haydn. In particular, he would have to lose all his memories, his goals, his unique skills, and his
entire personality would be obliterated and replaced by that of Haydn. By contrast, a human being
could retain her memories, her goals, her unique skills, and many important aspects of her
personality even as she becomes posthuman. This could make it possible for personal identity to
be preserved during the transformation into posthuman. 33
It is obvious that personal identity could be preserved, at least in the short run, if
posthuman status is achieved through radical healthspan enhancement. Suppose that I learnt that
tonight after I go to bed, a scientist will perform some kind of molecular therapy on my cells
32(Bostrom 2004).
See also (DeGrazia 2005). DeGrazia argues that identity-related challenges to human enhancement
largely fails, both ones based on considerations of personal identity and ones based on narrative identity(authenticity), although he mainly discusses more moderate enhancements than those I focus on in thispaper.
33

14

while I’m sleeping to permanently disable the aging processes in my body. I might worry that I
would not wake up tomorrow because the surgery might go wrong. I would not worry that I might
not wake up tomorrow because the surgery succeeded. Healthspan enhancement would help
preserve my personal identity. (If the psychological shock of discovering that my life-expectancy
had been extended to a thousand years were so tremendous that it would completely remold mypsyche, it is possible that the new me would not be the same person as the old me. But this is nota necessary consequence. 34 )Walter Glannon has argued that a lifespan of 200 years or more would be undesirable
because personal identity could not be persevered over such a long life. 35 Glannon’s argument
presupposes that personal identity (understood here as a determinant of our prudential concerns)
depends on psychological connectedness. On this view, we now have prudential interests in a
future time segment of our organism only if that future time segment is psychologicallyconnected to the organism’s present time segment through links of backward-looking memories
and forward-looking projects and intentions. If a future time segment of my brain will notremember anything about what things are like for me now, and if I now have no projects or
intentions that extend that far into the future, then that future time segment is not part of myperson. Glannon asserts that these psychological connections that hold us together as persons
could not extend over 200 years or so.
There are several problems with Glannon’s argument, even if we accept his metaphysics
of personal identity. There is no reason to think it impossible to have intentions and projects that
range over more than 200 years. This would seem possible even with our current humancapacities. For example, I can easily conceive of exciting intellectual and practical projects that
may take me many hundreds of years to complete. It is also dubious to assume that a healthy
future self several hundred years older than I am now might would be unable remember thingsfrom current life stage. Old people often remember their early adulthood quite well, and it is notclear that these memories always decline significantly over time. And of course, the concern
about distant future stages being unable to remember their earlier stages disappears completely if
we suppose that enhancements of memory capacity becomes available. 36 Furthermore, if Glennon
was right, it would follow that it is “undesirable” for a small child to grow up, since adults do notremember what it was like to be a small child and since small children do not have projects or
intentions that extend over time spans as long as decades. This implication would becounterintuitive. It is more plausible that it can be desirable for an agent to survive and continue
to develop, rather than to die, even if psychological connections eventually become attenuated. In
the same way, it could be desirable for us to acquire the capacity to have a posthuman healthy
lifespan, even if we could not remain the same person over time scales of several centuries.
The case that personal identify could be preserved is perhaps less clear-cut with regard toradical cognitive or emotional enhancement. Could a person become radically smarter, moremusical, or come to possess much greater emotional capacities without ceasing to exist? Here theanswer might depend more sensitively on precisely which changes we are envisaging, how thosechanges would be implemented, and on how the enhanced capacities would be used. The case forthinking that both personal identity and narrative identity would be preserved is arguably34

It is not even a psychologically plausible consequence even within the limitations of current human
psychology. Compare the case to that of a man on death row who has a remaining life-expectancy of 1 day.
An unexpected pardon suddenly extends this to 40 years – an extension by a factor of 14,610! He might bedelighted, stunned, or confused, but he does not cease to exist as a person. If he did, it would presumably be
bad for him to be pardoned.
Even if one believed (erroneously in my view) that mortality or aging were somehow essential
features of the persons we are, these features are consistent with vastly extended healthspan.
35(Glannon 2002).
36
It is clear that in order for an extremely long life to not become either static or self-repeating, it would benecessary that mental growth continues.

15

strongest if we posit that (a) the changes are in the form of addition of new capacities orenhancement of old ones, without sacrifice of preexisting capacities; and (b) the changes are
implemented gradually over an extended period of time; (c) each step of the transformation
process is freely and competently chosen by the subject; and (d) the new capacities do not preventthe preexisting capacities from being periodically exercised; (e) the subject retains her oldmemories and many of her basic desires and dispositions; (f) the subject retains many of her old
personal relationships and social connections; and (g) the transformation fits into the life narrativeand self-conception of the subject. Posthuman cognitive and emotional capacities could in
principle be acquired in such a way that these conditions are satisfied.
Even if not all the conditions (a)-(g) were fully satisfied in some particular transformation
process, the normatively relevant elements of a person’s (numerical or narrative) identity could
still be sufficiently preserved to avoid raising any fundamental identity-based objection to theprudentiality of undergoing such a transformation. We should not use a stricter standard fortechnological self-transformation than for other kinds of human transformation, such as
migration, career change, or religious conversion.
Consider again a familiar case of radical human transformation: maturation. You
currently possess vastly greater cognitive capacities than you did as an infant. You have also lost
some capacities, e.g. the ability to learn to speak a new language without an accent. Youremotional capacities have also changed and developed considerably since your babyhood. For
each concept of identity which we might think has relevant normative significance – personal(numerical) identity, narrative identity, identity of personal character, or identity of corecharacteristics – we should ask whether identity in that sense has been preserved in thistransformation.
The answer may depend on exactly how we understand these ideas of identity. For eachof them, on a sufficiently generous conception of the identity criteria, identity was completely orin large part preserved through your maturation. But then we would expect that identity in thatsense would also be preserved in many other transformations, including the ones that are no more
profound as that of a child growing into an adult; and this would include transformations thatwould make you posthuman. Alternatively, we might adopt conceptions that impose more
stringent criteria for the preservation of identity. On these conceptions, it might be impossible tobecome posthuman without wholly or in large part disrupting one form of identity or another.
However, on such restrictive conceptions, identity would also be disrupted in the transformationof child into adult. Yet we do not think it is bad for a child to grow up. Disruptions of identity inthose stringent senses form part of a normal life experience and they do not constitute a disaster,or a misfortune of any kind, for the individual concerned.
Why then should it bad for a person to continue to develop so that she one day matures
into a being with posthuman capacities? Surely it is the other way around. If this had been ourusual path of development, we would have easily recognized the failure to develop into a
posthuman as a misfortune, just as we now see it as a misfortune for a child to fail to develop
normal adult capacities.
Many people who hold religious beliefs are already accustomed to the prospect of an
extremely radical transformation into a kind of posthuman being, which is expected to take place
after the termination of their current physical incarnation. Most of those who hold such a viewalso hold that the transformation could be very good for the person who is transformed.

7. Commitments
Apart from the concern about personal identity, there is a second kind of reason why it might be
bad for a Bloggs to become a Haydn. Bloggs might be involved in various projects, relationships,
and may have undertaken commitments that he could not or would not fulfill if he became
Haydn. It would be bad for Bloggs to fail in these undertakings if they are important to him. For

16example, suppose that Mr. Bloggs is deeply committed to Mrs. Bloggs. His commitment to Mrs.
Bloggs is so strong that he would never want to do anything that contravenes any of Mrs. Bloggs’
most central preferences, and one of her central preferences is that Mr. Bloggs not become
posthuman. In this case, even though becoming posthuman might in some respects be good for
Mr. Bloggs (it would enable him to understand more, or to stay healthy longer, etc.) it might
nevertheless be bad for him all things considered as it would be incompatible with fulfilling oneof the commitments that are most important to him. 37
This reason for thinking that it might be bad for a person to become posthuman relies on
the assumption that it can be very bad for a person to forfeit on commitments that would be
impossible to fulfill as a posthuman. 38 Even if we grant this assumption, it does not follow that
becoming a posthuman would necessarily be bad for us. We do not generally have commitmentsthat would be impossible to fulfill as posthumans. It may be impossible for Mr. Bloggs to become
posthuman without violating his most important commitment (unless, of course, Mrs. Bloggs
should change her mind), but his is a special case.
Some humans do not have any commitments of importance comparable to that of Mr.
Bloggs to his wife. For such people the present concern does not apply. But even for many
humans who do have such strong commitments, becoming posthuman could still be good forthem. Their commitments could still be fulfilled if they became posthuman. This is perhaps
clearest in regard to our commitments to projects and tasks: most of these we could complete –indeed we could complete them better and more reliably – if we obtained posthuman capacities.
But even with regard to our specific commitments to people, it would often be possible to fulfill
these even if we had much longer healthspans or greatly enhanced cognitive or emotional
capacities.

8. Ways of life
In addition to concerns about personal identity and specific commitments to people or projects,
there is a third kind of reason one might have for doubting that it could be good for us to become
posthuman. This third kind of reason has to do with our interpersonal relations more broadly, andwith the way that the good for a person can be tied to the general circumstances and conditions inwhich she lives. One might think that the very concept of a good life for a human being is
inextricably wound up in the idea of flourishing within a “way of life” – a matrix of beliefs,
relationships, social roles, obligations, habits, projects, and psychological attributes outside ofwhich the idea of a “better” or “worse” life or mode of being does not make sense.
The reasoning may go something like this: It would not be good for a clover to grow intoa rhododendron, nor for a fly to start looking and behaving like a raven. Neither would it, on thisview, be good for a human to acquire posthuman capacities and start living a posthuman life. The
criterion for how well a clover is doing is the extent to which it is succeeding in realizing its own
particular nature and achieving the natural “telos” inherent in the clover kind; and the equivalent
might be said of the fly. For humans, the case may be more complicated as there is a greater
degree of relevant individual variation among humans than among other species. Different
37

We may include under this rubric any “commitments to himself” that Mr. Bloggs might have. For
example, if he has a firm and well-considered desire not to become posthuman, or if he has solemnly sworn
to himself never to develop any posthuman capacities, then it could perhaps on grounds of these earlier
desires or commitments be bad for Mr. Bloggs to become posthuman.
38
One may also hold that a person in Mr. Bloggs’ situation has additional reasons for not becoming
posthuman that don’t rely on it being worse for him to become posthuman. For instance, he might havemoral reasons not to become posthuman even if it would be good for him to become one. Here I am
concerned with the question whether it would necessarily be bad for Bloggs to become posthuman, so any
moral reasons he might have for declining the transition would only be relevant insofar as they would makethe outcome worse for Mr. Bloggs.

17

humans are pursuing different “ways of life”, so that what counts as flourishing for one humanbeing might differ substantially from what counts as such for another. Nevertheless, as we are all
currently pursuing human ways of life, and since what is good for us is defined by reference to
our way of life, it is not the case for any human that it would be good for her to become
posthuman. It might be good for posthumans to be posthumans, but it would not be good forhumans to become posthuman.
This third concern seems to be a conglomerate of the two concerns we have alreadydiscussed. Why could it not be good for a human to become posthuman? One possible reason is if
her personal identity could not be preserved through such a transformation. The comparison withthe clover appears to hint at this concern. If a clover turned into a rhododendron, then the clover
would presumably cease to exist in the process. If a fly started looking and behaving like a raven,would it still be a fly? So part of what is going on here seems to be that the assertion that therelevant form of identity could not be preserved in the transformations in question. But we havealready addressed this concern insofar as it pertains to humans becoming posthuman.
There might be more at stake with this third concern than identity. The problem with aclover becoming a rhododendron is not just that the clover might cease to exist in the process, butthat it seems a mistake to think that being a rhododendron is in any sense better than being a
clover. There might be external criteria of evaluation (such as economic or aesthetic value to thehuman owner) according to which a rhododendron is better or more valuable than a clover. But
aside from such extrinsic considerations, the two plants seem to be on a par: a thriving clover
thrives just as much as a thriving rhododendron, so if the good for a plant is to thrive then neither
kind is inherently better off or has a greater potential for realizing a good life than the other. Our
challenger could claim that the same holds vis-à-vis a human and a posthuman.
I think the analogy is misleading. People are not plants, and the concept of a valuable
mode of being for a person is fundamentally different from that of the state of flourishing for aplant. In a metaphorical sense we can ascribe interests to plants and other non-sentient objects:
this clover “could use” some water; that clock “needs” winding up; the squeaky wheel “would
benefit” from a few drops of oil. Defining interests relative to a functionalist basis might be theonly way we can make sense of these attributions. The function of the clock is to indicate thetime, and without being wound up the clock would fail to execute this function; thus it “needs” tobe wound up. Yet sentient beings may have interests not only in a metaphorical sense, based on
their function, but in a quite literal sense as well, based on what would be normatively good forthem. A human being, for example, might have interests that are defined (partially) in terms ofwhat she is actually interested in, or would be interested in given certain conditions. 39 So fromthe fact that we could not make sense of the claim that it would be good for a clover to become arhododendron, it does not follow that we would similarly be unable to make sense of the claimthat it would be good for a human to become a posthuman. Even if the successful execution of“the function” of a human were not facilitated by becoming posthuman, there would be othergrounds on which one could sensibly attribute to a human an interest in becoming posthuman.
It is at any rate highly problematic that something as complex and autonomous as ahuman being has any kind of well-defined “function”. The problem remains even if we relativize
the function to particular ways of life or particular individuals. We might say that the function of
the farmer is to farm, and that of the singer is to sing, etc. But any particular farmer is a host ofother things as well: e.g. a singer, a mother, a sister, a homeowner, a driver, a television watcher,and so forth ad infinitum. Once she might have been a hairdresser; in the future she might becomea shopkeeper, a golfer, a person with a disability, a transsexual, or a posthuman. It is difficult tosee how any strong normative conclusions could be drawn from the fact that she currently
occupies a certain set of roles and serves a certain set of functions. At most we could conclude
that when and insofar as she acts as a farmer, she ought to tend to her crops or livestock; but from39

Cmp. dispositional theories of value, discussed above.

18

the fact that she is a farmer, nothing follows about whether she ought to be or remain a farmer.
Likewise, the most we could conclude from the fact that she is currently a human person is that
she ought to do things that are good for humans – brush her teeth, sleep, eat, etc. – but only solong as she remains human. If she became a posthuman who did not need to sleep, she would nolonger have any reason so sleep. And the fact that she currently has a reason to sleep is not areason for her not to become a sleepless posthuman.
At this point, an objector could attempt an alternative line of argumentation. Maybe there
are some crucial interests that we have that are not conditional on us occupying particular social
roles or having particular personal characteristics or serving particular functions. These interests
would be unlike our interest in sleep, which does not provide us with a reason not to change insuch a way that we no longer need to sleep. Rather these unconditional (“categorical”) interests
would be such as to give us reason not to change in ways that would make us no longer havethose interests.
I have already admitted that individuals can have such interests, and in some cases thismight make it the case for some possible individuals that it would not be good for them tobecome posthuman. I discussed this above as the “second concern”. This is not a problem for myposition since it is compatible with it being true for other individuals (and perhaps for the
overwhelming majority or even all actual human persons) that it could be good for them tobecome posthuman. But our hypothetical objector might argue that there are certain categoricalinterests we all have qua humans. These interests would somehow derive from human nature andfrom the natural ends and ideals of flourishing inherent in this essential nature. Might not theexistence of such universally shared categorical human interests invalidate the thesis that it could
be good for us to become posthuman?

9. Human nature
Let us consider two different candidate ideas of what a human “telos” might be.
If we seek a telos for human individuals within a naturalistic outlook, one salient
candidate would be the maximization of that individual’s inclusive fitness. Arguably, the mostnatural way to apply a functional characterization of a human individual from an evolutionary
perspective is as an inclusive fitness maximizer (tuned for life in our ancestral environment).
From this perspective, our legs, our lungs, our sense of humor, our parental instincts, our sex
drive and romantic propensities subserve the ultimate function of promoting the inclusive fitnessof an individual. Now if we define the telos of a human individual in this way, as vehicle for theeffective promulgation of her genes, then many of the seemingly most attractive posthumanpossibilities would be inconsistent with our successfully realizing this alleged telos, in particular
those possibilities that involve radical alteration of the human genome. (Replacing our genes withother genes does not seem to be an effective way to promulgate the genes we have.)
As a conception of the human good, however, the telos of maximizing inclusive fitness is
singularly lacking in plausibility. I do not know of any moral philosopher who advocates such aview. It is too obvious that what is good for a person can, and usually does, diverge from what
would maximize that person’s inclusive fitness. 40 Those who attempt to derive a theory of thehuman good from the telos inherent in a conception of human functioning will need to start fromsome conception of human functioning other than the evolutionary one.
One starting point that has had more appeal is the doctrine that a human being isessentially a rational animal and that the human telos is the development and exercise of ourrational faculties. Views of this sort have a distinguished pedigree that can be traced back at least
to Aristotle. Whatever the merits of this view, however, it is plainly not a promising objection to40

For example, for a contemporary man the life plan that would maximize inclusive fitness might be tosimply donate as much sperm to fertility clinics as possible.

19the claims I advance in this paper, since it would be perfectly possible for a posthuman to realize
a telos of rationality as well as a human being could. In fact, if what is good for us is to develop
and exercise our rational nature, this implies that it would be good for us to become posthumans
with appropriately enhanced cognitive capacities (and preferably with extended healthspan too, sothat we may have more time to develop and enjoy these rational faculties).
One sometimes hears it said that it is human nature to attempt to overcome every limit
and to explore, invent, experiment, and use tools to improve the human condition. 41 I don’t knowthat this is true. The opposite tendency seems to be at least as strong. Many a great invention was
widely resisted at the time of its introduction, and inventors have often been viciously persecuted.
If one wished to be provocative, one might even say that humanity has advanced technologicallyin spite of anti-technological tendencies in human nature, and that technological advancement
historically has been due more to the intrinsic utility of technological inventions and thecompetitive advantages they sometimes bestow on their users than to any native preference
among the majority of mankind for pushing boundaries and welcoming innovation. 42 Be that as it
may; for even if it were “part of human nature” to push ever onward, forward, and upward, I do
not see how anything follows from this regarding the desirability of becoming posthuman. Thereis too much that is thoroughly unrespectable in human nature (along with much that is admirable),for the mere fact that X is a part of human nature to constitute any reason, even a prima faciereason, for supposing that X is good.

11. Brief sketches of some objections and replies
Objection: One might think that it would be bad for a person to be the only posthuman being
since a solitary posthuman would not have any equals to interact with.
Reply: It is not necessary that there be only one posthuman.
I have acknowledged that capacities may not have basic intrinsic value and that thecontribution to well-being that having a capacity makes depends on the context. I suggested that itnevertheless makes sense to talk of the value of a capacity in a sense similar to that in which wecommonly talk of the value of e.g. money or health. We can take such value ascriptions asassertions that the object or property normally makes a positive contribution to whatever hasbasic value. When evaluating posthuman attributes, the question arises what we should take to be
the range of circumstances against which we assess whether something “normally” makes apositive contribution. As we do not have a concrete example in front of us of a posthumancivilization, there is a certain indeterminacy in any assertion about which things or attributes
would “normally” make a positive contribution in a posthuman context. At this point, it may
therefore be appropriate to specify some aspects of the posthuman context that I assume in myvalue-assertions. Let me here postulate that the intended context is one that includes a society of
posthuman beings.
41

The quest for posthuman capacities is as old as recorded history. In the earliest preserved epic, theSumerian Epic of Gilgamesh (approx. 1700 B.C.), a king sets out on a quest for immortality. In later times,
explorers sought the Fountain of Youth, alchemists labored to concoct the Elixir of Life, and various
schools of esoteric Taoism in China strove for physical immortality by way of control over or harmony
with the forces of nature. This is in addition to the many and diverse religious traditions in which the hopefor a supernatural posthuman existence is of paramount importance.
42
As J.B.S. Haldane wrote: “The chemical or physical inventor is always a Prometheus. There is no great
invention, from fire to flying, which has not been hailed as an insult to some god. But if every physical andchemical invention is a blasphemy, every biological invention is a perversion. There is hardly one which,on first being brought to the notice of an observer from any nation which has not previously heard of their
existence, would not appear to him as indecent and unnatural.” (Haldane 1924).

20What dialectical constraints are there on what I am allowed to stipulate about the
posthuman context? The main cost to making such stipulations is that if I end up defining agerrymandered “posthuman context”, which is also extremely unlikely ever to materialize, thenthe significance of any claims about what would normally be valuable in that context would tend
to wane. It is simply not very interesting to know what would “normally” be valuable in someutterly bizarre context defined by a large number of arbitrary stipulations. I do not think that bypostulating a society of posthumans I am significantly hollowing out my conclusions. I do, in
fact, assume throughout this paper more generally that the postulated posthuman reference
society is one that is adapted to its posthuman inhabitants in manners similar to the way current
human society is adapted to its human inhabitants. 43 I also assume that this reference society
would offer many affordances and opportunities to its posthuman inhabitants broadly analogous
to those which contemporary society offers humans. I do not intend by this postulation to express
any prediction that this is the kind of posthuman society that is most likely to form, nor do I mean
to imply that being a posthuman could not be valuable even outside of the context of such a kindof society. The postulation is merely a way of delimiting the claims I am trying to defend in thispaper.
Objection: The accumulated cultural treasures of humanity might lose their appeal to somebody
whose capacities greatly exceeded those of the humans who produced them. More generally,
challenges that seemed interesting to the person while she was still human might become trivial
and therefore uninteresting to her when she acquires posthuman capacities. This could deprive
posthumans of the good of meaningful achievements.
Reply: It is not clear why the ability to appreciate what is more complex or subtle should make it
impossible to appreciate simpler things. Somebody who has learnt to appreciate Schoenberg may
still delight in simple folk songs, even bird songs. A fan of Cézanne may still enjoy watching asunrise.
Even if it were impossible for posthuman beings to appreciate some simple things, they
could compensate by creating new cultural riches. I am assuming that the reference society would
offer opportunities for doing this – see above.
If some challenges become too easy for posthumans, they could take on more difficult
challenges. One might argue that an additional reason for developing posthuman cognitive
capacities is that it would increase the range of interesting intellectual challenges open to us. At
least within the human range of cognitive capacity, it seems that the greater one’s capacity, themore numerous and meaningful the intellectual projects that one can embark on. When one’s
mind grows, not only does one get better at solving intellectual problems – entirely new
possibilities of meaning and creative endeavor come into view.
Objection: A sense of vulnerability, dependence, and limitedness can sometimes add to the valueof a life or help a human being grow as a person, especially along moral or spiritual dimensions.
Reply: A posthuman could be vulnerable, dependent, and limited.
A posthuman could also be able to grow as a person in moral and spiritual dimensions
without those extrinsic spurs that are sometimes necessary to affect such growth in humans. The
ability to spontaneously develop in these dimensions could be seen as an aspect of emotional
capacity.
Objection: The very desire to overcome one’s limits by the use of technological means rather
than through one’s own efforts and hard work could be seen as expressive of a failure to open
43

But I do not assume that the reference society would only contain posthuman beings.

21

oneself to the unbidden, gifted nature of life, or as a failure to accept oneself as one is, or as selfhate. 44
Reply: This paper makes no claims about the expressive significance of a desire to become
posthuman, or about whether having such a desire marks one as a worse person, whether
necessarily or statistically. The concern here rather is about whether being posthuman could begood, and whether it could be good for us to become posthuman.
Objection: A capacity obtained through a technological shortcut would not have the same value
as one obtained through self-discipline and sacrifice.
Reply: I have argued that the possession of posthuman capacities could be extremely valuable
even were the capacities are effortlessly obtained. It is consistent with what I have said that
achieving a capacity through a great expenditure of blood, sweat, and tears would further increase
its value. I have not addressed what would be the best way of becoming posthuman. We may
note, however, that is unlikely that we could in practice become posthuman other than via
recourse to advanced technology.
Objection: The value of achieving a goal like winning a gold medal in the Olympics is reduced
and perhaps annulled if the goal is achieved through inappropriate means (e.g. cheating). The
value of possessing a capacity likewise depends on how the capacity was acquired. Even thoughhaving posthuman capacities might be extremely valuable if the capacities had been obtained byappropriate means, there are no humanly possible means that are appropriate. Any means bywhich humans could obtain posthuman capacities would negate the value of having suchcapacities.
Reply: The analogy with winning an Olympic medal is misleading. It is in the nature of sports
competitions that the value of achievement is intimately connected with the process by which it
was achieved. We may say that what is at stake in the analogy is not really the value of a medal,
nor even the value of winning a medal, but rather (something like) winning the medal by certain
specified means in a fair competition, in a non-fluke-like way, etc. Many other goods are not likethis. When we visit the doctor in the hope of getting well, we do not usually think that the valueof getting well is strongly dependent on the process by which health is achieved; health and theenjoyment of health are valuable in their own right, independently of how these states comeabout. Of course, we are concerned with the value of the means to getting well – the means
themselves can have negative value (involving perhaps pain and inconvenience), and inevaluating the value of the consequences of an action, we take the value of the means into
account as well as the value of the goal that they achieve. But usually, the fact that some means
have negative value does not reduce the value of obtaining the goal state.
One possible exception to this is if the means are in a certain sense immoral. We might
think that a goal becomes “tainted”, and its value reduced, if it was achieved through deeply
immoral means. For example, some might hold that the value of medical findings obtained by
Nazi doctors in concentration camps have reduced or no value because of the way the findings
were produced. Yet this radical kind of “taint” is a rather special case. 45 Having to use bad means
might be good reason not to pursue a goal, but typically this is not because the use of bad means
44

Cmp. (Sandel 2004), although it is not clear that Sandel has an expressivist concern in mind.
Even in the Nazi doctor example, it is plausibly the achievement of the doctors (and of Germany etc.)that is tainted, and the achievement’s value that is reduced. The value of the results is arguably unaffected,
although it might always be appropriate to feel uncomfortable when employing them, appropriate topainfully remember their source, regret the way we got them, and so forth.
45

22

would reduce the value of the attainment of the goal, but rather it is either because the means
themselves have more negative value than the goal has positive value, or (on a nonconsequentialist view) because it is morally impermissible to use certain means independently of
the total value of the consequences. 46
The values that I have alleged could be derived from posthuman capacities are not likethe value of an Olympic gold medal, but rather like the value of health. I am aware of no logical,
metaphysical, or “in principle” reason why humans could not obtain posthuman capacities inways that would avoid recourse to immoral means of the sort that would “taint” the outcome(much less that would taint the outcome to such a degree as to annul its extremely high surplus
value). It is a further question to what extent it is practically feasible to work towards realizing
posthuman capacities in ways that avoid such taint. This question lies outside the scope of thepresent paper. My conclusion may therefore be understood to implicitly contain the proviso thatthe posthuman capacities of which I speak have been obtained in ways that are non-Faustian.
Objection: Posthuman talent sets the stage for posthuman failure. Having great potential mightmake for a great life if the potential is realized and put to some worthwhile use, but it could
equally make for a tragic life if the potential is wasted. It is better to live well with modest
capacities than to life poorly with outstanding capacities.
Reply: We do not lament that a human is born talented on grounds that it is possible that she will
waste her talent. It is not clear why posthuman capacity would be any more likely to be wasted
than human capacity. I have stipulated that the posthuman reference society would offer
affordances and opportunities to its posthuman inhabitants broadly analogous to those that
contemporary society offers humans. If posthumans are more prone to waste their potential, it
must therefore be for internal, psychological reasons. But posthumans need not be any worse thanhumans in regard to their readiness to make the most of their lives. 47

12. Conclusion
I have argued, first, that some posthuman modes of being would be extremely worthwhile; and,second, that it could be good for most human beings to become posthuman.
I have discussed three general central capacities – healthspan, cognition, and emotion –separately for most of this paper. However, some of my arguments are strengthened if one
considers the possibility of combining these enhancements. A longer healthspan is more valuable
when one has the cognitive capacity to find virtually inexhaustible sources meaning in creative46

It might help to reflect that we do not deny the value of our current human capacities on grounds of theirevolutionary origin, even though this origin is (a) largely not a product of human achievement, and (b)fairly drenched in violence, deceit, and undeserved suffering. People who are alive today also owe their
existence to several thousands of years of warfare, plunder, and rape; yet this does not entail that ourcapacities or our mode of existence is worthless.
Another possibility is that the result has positive value X, the way you get it has negative value Y,
but the “organic whole” comprising both the result and the way it was obtained has an independent value of
its own, Z, which also might be negative. On a Moorean view, the value of this situation “on the whole”
would be X+Y+Z, and this might be negative even if X is larger than (–Y) (Moore 1903). Alternatively, Z
might be incommensurable with X+(–Y). In either case, we have a different situation than the one
described above in the text, since here X could invariant under different possible ways in which the result
was obtained. However, I do not know of any reason to think that this evaluative situation, even if
axiologically possible, would necessarily obtain in the sort of case we are discussing. (I’m indebted to Guy
Kahane for this point.)
47
If they have enhanced emotional capacity, they may be more motivated and more capable than mosthumans of realizing their potential in beautiful ways.

23

endeavors and intellectual growth. Both healthspan and cognition are more valuable when one
has the emotional capacity to relish being alive and to take pleasure in mental activity.
It follows trivially from the definition of “posthuman” given in this paper that we are notposthuman at the time of writing. It does not follow, at least not in any obvious way, that a
posthuman could not also remain a human being. Whether or not this is so depends on whatmeaning we assign to the word “human”. One might well take an expansive view of what itmeans to be human, in which case “posthuman” is to be understood as denoting a certain possible
type of human mode of being – if I am right, an exceedingly worthwhile type. 48

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