philosophical presentism is the view that neither the future nor the past exist .

in some versions of presentism , this view is extended to timeless objects or ideas ( such as numbers ) .

according to presentism , events and entities that are wholly past or wholly future do not exist at all .

presentism contrasts with eternalism and the growing block theory of time which hold that past events , like the battle of waterloo , and past entities , like alexander the great 's warhorse bucephalus , really do exist , although not in the present .

eternalism extends to future events as well .

saint augustine proposed that the present is analogous to a knife edge placed exactly between the perceived past and the imaginary future and does not include the concept of time .

this should be self-evident because , if the present is extended , it must have separate parts – but these must be simultaneous if they are truly a part of the present .

according to early philosophers , time can not be simultaneously past and present and hence not extended .

contrary to saint augustine , some philosophers propose that conscious experience is extended in time .

for instance , william james said that time is " the short duration of which we are immediately and incessantly sensible " .

other early presentist philosophers include the indian buddhist tradition .

fyodor shcherbatskoy , a leading scholar of the modern era on buddhist philosophy , has written extensively on buddhist presentism : " everything past is unreal , everything future is unreal , everything imagined , absent , mental ... is unreal .

ultimately , real is only the present moment of physical efficiency [ i.e. , causation ] . "

according to j. m. e. mctaggart 's , the unreality of time , there are two ways of referring to events : the ' a series ' ( or ' tensed time ' : yesterday , today , tomorrow ) and the ' b series ' ( or ' untensed time ' : monday , tuesday , wednesday ) .

presentism posits that the a series is fundamental and that the b series alone is not sufficient .

presentists maintain that temporal discourse requires the use of tenses , whereas the " old b-theorists " argued that tensed language could be reduced to tenseless facts ( dyke , 2004 ) .

arthur prior has argued against un-tensed theories with the following ideas : the meaning of statements such as " thank goodness that 's over " is much easier to see in a tensed theory with a distinguished , present now .

similar arguments can be made to support the theory of egocentric presentism ( or perspectival realism ) , which holds that there is a distinguished , present self .

in modern theory of relativity , the conceptual observer is at a geometric point in both space and time at the apex of the ' light cone ' which observes the events laid out in time as well as space .

different observers may disagree on whether two events at different locations occurred simultaneously depending on whether the observers are in relative motion ( see relativity of simultaneity ) .

this theory depends upon the idea of time as an extended thing and has been confirmed by experiment , thus giving rise to a philosophical viewpoint known as four dimensionalism .

although the contents of an observation are time-extended , the conceptual observer , being a geometric point at the origin of the light cone , is not extended in time or space .

this analysis contains a paradox in which the conceptual observer contains nothing , even though any real observer would need to be the extended contents of an observation to exist .

this paradox is partially resolved in relativity theory by defining a ' frame of reference ' to encompass the measuring instruments used by an observer .

this reduces the time separation between instruments to a set of constant intervals .

some of the difficulties and paradoxes of presentism can be resolved by changing the normal view of time as a container or thing unto itself and seeing time as a measure of changing spatial relationships among objects .

thus , observers need not be extended in time to exist and to be aware , but they rather exist and the changes in internal relationships within the observer can be measured by stable countable events .

philosophical presentism

zimmerman , dean , 1996 , “persistence and presentism , ” philosophical papers , 25 : 115–126 .
here are a variety of brief philosophical arguments against past - directed time travel .
––– , 1995 , “the open past , ” philosophical studies , 79 : 95–105 .
presentism is opposed by non - presentism , which is the view that there are some non - present objects . more precisely , non - presentism is the view that , possibly , it is sometimes true that there are some non - present objects .
bourne , craig , 2006 , a future for presentism , oxford : oxford university press .
bigelow , john , 1996 , “presentism and properties , ” in james tomberlin ( ed . ) , philosophical perspectives ( volume 10 : metaphysics ) , oxford : blackwell , pp . 35–52 .
––– , 1999 , “presentism and ontological commitment , ” journal of philosophy , 96 : 325–347 .
a brief defense of presentism , the view that the past and the future are not real .
––– , 1989b , “persistence , change , and explanation , ” philosophical studies , 56 : 1–28 .
vihvelin , kadri , 1996 , “what time travelers cannot do , ” philosophical studies , 81 : 315–330 .
despite the fact that presentism has the firm backing of common sense and eternalism revolts against it , eternalism is widely regarded as almost the default view in contemporary debates , and presentism as a highly problematic view .
rea , michael c . , 1998 , “temporal parts unmotivated , ” the philosophical review , 107 : 225–260 .
besson , corine and hattiangadi , anandi , forthcoming , “the open future , bivalence and assertion , ” philosophical studies .
godfrey - smith , william , 1979 , “special relativity and the present , ” philosophical studies , 36 : 233–244 .
sullivan , meghan , 2012a , “the minimal a - theory , ” philosophical studies , 158 : 149 - 174 .
––– , 1994 , “the 3d / 4d controversy and non - present objects , ” philosophical papers , 23 : 243–249 .
to put the matter in the modal language , worlds that include closed timelike curves have no place for presentism and tense .
a series of popular lectures about time by a renowned physicist with an interest in philosophical issues , but emphasizing the arrow of time .
––– , 2011 , “on the meaning of the question ‘how fast does time pass ? ’ , ” philosophical studies , 155 : 325–344 .
the entirety of part ii of the book is devoted to the hard task of defending presentism in the face of special and general relativity .
these defects are somewhat mitigated in bourne ' s more helpful discussion of presentism ' s standing vis - à - vis general relativity and cosmology .
meiland , jack w . , 1974 , “a two - dimensional passage model of time for time travel , ” philosophical studies , 26 : 153–173 .
philosophical presentism philosophical presents is the philosophical doctrine that recognizes only the events and entities that occur in the present or past . in some versions of presentism , this is extended to timeless objects or ideas such as numbers . = = = = = = = image - copyright - info = = = = = = = = license : creative commons attribution - share alike 3 . 0 ( cc - by - sa - 3 . 0 ) licenselink : urltoken author - info : user : s sepp image source : urltoken = = = = = = = image - copyright - info = = = = = = = = - video is targeted to blind users attribution : article text available under cc - by - sa image source in video urltoken
another argument that might be raised against the possibility of time travel depends on the claim that presentism is true . for if presentism is true , then neither past nor future objects exist . and in that case , it is hard to see how anyone could travel to the past or the future .
craig bourne , a future for presentism , oxford university press , 2006 , 242pp . , $ 55 . 00 ( hbk ) , isbn : 9780199212804
reviews the arguments for and against the claim that , since the present in the theory of relativity is relative to reference frame , presentism must be incorrect .
eternalism contrasts to presentism and is thought of as its opposite . eternalism is the philosophical theory which says that all points in time are equally real . the past , the present , and the future are all real . in this sense , socrates and tomorrow’s events exist right now , even if i cannot see them or interact with them . many philosophers have adopted eternalism because they argue that presentism is contradicted by einstein’s special and general theory of relativity , whereas eternalism agrees with it . as the philosopher of science , dean rickles puts it : “the consensus among philosophers seems to be that special and general relativity are incompatible with presentism . ”
lewis , david , 1986a , “the paradoxes of time travel , ” in lewis , david , philosophical papers ( volume 2 ) , oxford : oxford university press .
for a review of the argument from relativity against presentism , and for some criticisms of the block theory , see ( putnam 1967 ) and ( saunders 2002 ) .
savitt , steven ( ed . ) , 1995 , time ' s arrows today : recent physical and philosophical work on the direction of time , cambridge : cambridge university press .
––– , 2003 , “a defense of presentism , ” in dean zimmerman ( ed . ) , oxford studies in metaphysics ( volume 1 ) , oxford : oxford university press .
markosian , ned , “a defense of presentism , ” in zimmerman , dean ( ed . ) , oxford studies in metaphysics , vol . 1 , oxford university press , 2003 .
more importantly , it is utterly unclear what relation , if any , the cosmological time may bear to the phenomenological local time , which is the real source of many issues surrounding presentism .
hinchliff , mark , 1996 , “the puzzle of change , ” in james tomberlin ( ed . ) , philosophical perspectives ( volume 10 : metaphysics ) , oxford : blackwell , pp . 119–136 .
––– , 1998 , “temporary intrinsics and presentism , ” in peter van inwagen and dean zimmerman ( eds . ) , metaphysics : the big questions , oxford : blackwell , pp . 206–219 .
the three answers just given to the question ,
what is time ?
are informative . however , when philosophers ask the question , they normally do not want such a succinct answer . they want to be told more about the nature of time . they complain that the full nature of physical time can be revealed only by adding a philosophical theory of time that addresses the many philosophical issues that scientists do not concern themselves with .
the philosophical dispute about presentism , the growing - past theory , and the block theory or eternalism has taken a linguistic turn by focusing upon a question about language : “are predictions true or false at the time they are uttered ? ” those who believe in the block - universe ( and thus in the determinate reality of the future ) will answer “yes , ” while a “no” will be given by presentists and advocates of the growing - past .
unlike some other presentists , he does not think eternalism is utterly untenable ; instead he thinks it is a theory to beat , and he takes up the formidable challenge of defending a version of presentism against all the odds .
earman , john , 1995 , “recent work on time travel , ” in steven savitt ( ed . ) , time ' s arrows today : recent physical and philosophical work on the direction of time , cambridge : cambridge university press , pp . 268–310 .
philosophers of time would like to resolve as many issues as they can from the list of philosophical issues mentioned in the opening summary . some issues are intimately related to others so that it is reasonable to expect a resolution of one to have deep implications for another . for example , there is an important subset of related philosophical issues about time that cause many philosophers of time to divide into two broad camps , the a - camp and the b - camp , because they are on the opposite sides of those issues .
one philosophical implication of the relativity of time is that it seems to be more difficult to defend mctaggart ' s a - theory that says temporal properties of events such as
is happening now
or
happened in the past
are frame - free properties of those events .
presentism is the view that only present objects exist . more precisely , it is the view that , necessarily , it is always true that only present objects exist . ( at least , that is how the name ‘presentism’ will be used here . some writers have used the name differently . note that , unless otherwise indicated , what is meant here by ‘present’ is temporally present , as opposed to spatially present . ) according to presentism , if we were to make an accurate list of all the things that exist — i . e . , a list of all the things that our most unrestricted quantifiers range over — there would be not a single non - present object on the list . thus , you and the taj mahal would be on the list , but neither socrates nor any future martian outposts would be included . ( assuming , that is , both ( i ) that each person is identical to his or her body , and ( ii ) that socrates ' s body ceased to be present — thereby going out of existence , according to presentism — shortly after he died . those who reject the first of these assumptions should simply replace the examples in this article involving allegedly non - present people with appropriate examples involving the non - present bodies of those people . ) and it ' s not just socrates and future martian outposts , either — the same goes for any other putative object that lacks the property of being present . all such objects are unreal , according to presentism .
despite the claim by some presentists that theirs is the common sense view , it is pretty clear that there are some major problems facing presentism ( and , to a lesser extent , the growing universe theory ; but in what follows we will focus on the problems facing presentism ) . one problem has to do with what appears to be perfectly meaningful talk about non - present objects , such as socrates and the year 3000 . if there really are no non - present objects , then it is hard to see what we are referring to when we use expressions such as ‘socrates’ and ‘the year 3000’ .
the likely philosophical implications of eternal inflation are that ( i ) everything that can happen will happen , ( ii ) future time is countably infinite , ( iii ) the universe has no maximum entropy , and ( iv ) there are no poincaré cycles requiring the universe to return infinitesimally close to every one of its earlier states .
‘non - presentism’ is an umbrella term that covers several different , more specific versions of the view . one version of non - presentism is eternalism , which says that objects from both the past and the future exist just as much as present objects . according to eternalism , non - present objects like socrates and future martian outposts exist right now , even though they are not currently present . we may not be able to see them at the moment , on this view , and they may not be in the same space - time vicinity that we find ourselves in right now , but they should nevertheless be on the list of all existing things .
- -
ersatzer presentism ,
systematically developed in chapter 2 - - is similar to some others in that it takes times to be abstract entities : maximally consistent sets of propositions of a certain type , which represent , in a relevant way , past , present and future states of affairs and their cross - temporal relations .
a third major issue for the presentist is to account for the special theory of relativity ' s treatment of the present , given that it implies there is no common global present , but only different presents for each of us . relativity theory allows event a to be simultaneous with event b in some reference frame , and it allows be to be simultaneous with event c in some other reference frame . so , if a is real , then shouldn’t the presentist allow c to be real also ? yet , according to relativity theory , in the first frame , c might be in the future of a . this argument against presentism presupposes the transitivity of co - existence . ( stein 1991 ) says presentism can be retained by rejecting transitivity and saying what is present and thus real is different depending on your spacetime location . the implication of this is that , for event a , the only events that are real are those with a zero spacetime interval from a , and many of stein ' s opponents do not like this implication . a survey of defenses of presentism can be found in ( markosian 2003 ) .
you can participate in that future , not just view it . a relevant philosophical controversy is whether there can be time travel that changes the future . this is impossible , according to david lewis ( lewis 1976 , 150 ) . if you were to do that , then it would not have been the future . no action changes the future , regardless of whether time travel is involved .
a look at the brain structures involved in how our mind organizes our experiences into the proper temporal order . includes a discussion of benjamin libet’s claim to have discovered in the 1970s that the brain events involved in initiating a free choice occur about a third of a second before we are aware of our making the choice . this claim has radical implications for the philosophical issue of free will .
there is another important respect in which some ( but not all ) a theorists believe time to be unlike the dimensions of space . some a theorists believe that there are crucial ontological differences between time and the dimensions of space . for some a theorists also endorse a view known as “presentism , ” and others endorse a view that we will call “the growing universe theory . ”
proponents of the tensed theory of time do not agree with this conclusion . quentin smith says , the
new tenseless theory of time is faced with insurmountable problems , and that it ought to be abandoned in favor of the tensed theory .
so , the philosophical debate continues over whether tensed concepts have semantical priority over untensed concepts , and whether tensed facts have ontological priority over untensed facts .
the advocates of the block - universe attack both presentism and the growing - past theory by claiming that only the block - universe can make sense of the special theory of relativity’s implication that , if persons a and b are separated but in relative motion , an event in person a’s present can be in person b’s future . advocates of presentism and the growing - past theories must suppose that this event is both real and unreal because it is real for a but not real for b . surely that conclusion is unacceptable , claim the eternalists . two key assumptions of this argument are , first , that relativity does provide an accurate account of the spatiotemporal relations among events , and , second , that if there is some frame of reference in which two events are simultaneous , then if one of the events is real , so is the other .
assuming that the subject of admiration is plato himself ( and not his achievements , as the case might be : that case constitutes no problem whatsoever for the presentist ) , bourne notes that , pace some critics of presentism , the problem here lies not in the spurious relation of admiration , but in the need to talk about , or refer to , plato and other past objects , and that problem has already been dealt with .
a small number of philosophers question whether time seems to us to flow , and claim we are mistaken in describing how things seem to us to be . the vast majority , though , will agree that that time seems to flow , but there is significant philosophical disagreement among these philosophers about whether it really does . this controversial issue is about physical time , and it is directly related to whether mctaggart ' s a - theory or b - theory is more fundamental .
there is a philosophical problem about eddington ' s claim that entropy causes the arrow . it is not controversial that there is a correlation between time ' s arrow and the direction of entropy change . what is controversial is whether there ' s an identity or even a causal connection between the two . an alternative suggestion is that there is an intrinsic asymmetry in the geometry of spacetime that produces time ' s arrow , and the arrow is merely highly correlated with entropy change .
the philosopher ted sider says , “presentism is the doctrine that only the present is real… a presentist thinks that everything is present ; more generally , that , necessarily , it is always true that everything is ( then ) present . ” with this definition , the past and future do not exist – they are not real ! that is why presentism is so mind - boggling because we are constantly thinking about the past and planning for the future . but according to this theory , the past and future only exist subjectively – it is only the present which exists objectively ( outside of our minds ) . also , if we take a statement like “newton exists” , then this statement could only be true if it was said when newton existed in the present , say in 1666 . if we say that statement now , then it is false . when making statements about what exists , the truth of the statement depends on the context ( when the statement was made ) .
ok , i’m not going to argue the philosophical against the physics because i’ve learned that philosophy is inferior to physics . why ? because philosophy isn’t about solving anything . it’s about arguing a psosition and not giving a damn about whether it’s ever resolved or not because that would bring the argument to an end . physics isn’t like that . in physics , we want to known the answers because the answers determine whether our theories are correct so that we can make accurate predictions about them . not at all the same goals of philosophy .
according to the eternalist , temporal location matters not at all when it comes to ontology . but according to a somewhat less popular version of non - presentism , temporal location does matter when it comes to ontology , because only objects that are either past or present — but not objects that are future — exist . on this view , which we can call “the growing universe theory , ” the universe is always increasing in size , as more and more things are added on to the front end ( temporally speaking ) .
( 1 ) according to the ontological theory called presentism , necessarily only present physical objects exist . stated another way : necessarily , if something is physically real , then it exists now . the presentist maintains that , unlike the present , both the past and the future are not real , so if a statement about the past is true , such as
dinosaurs once existed ,
this must be because some present facts make it true . heraclitus , duns scotus , thomas hobbes , and a . n . prior are presentists .
the philosophical disagreement about tenses is not so much about tenses in the grammatical sense , but rather about the significance of the distinctions of past , present , and future which those tenses are used to mark . the main metaphysical disagreement is about whether times and events have non - relational properties of pastness , presentness , and futurity . does an event have or not have the property of , say , prresentness independent of the event ' s relation to us and our temporal location ? the a - camp says it does ; the b - camp disagrees .
there are problems with presentism , however , such as , how the theory relates to the flow of time . if time passes , then does every event not exist in the past , present , and future ? if there are no events which are in the past or in the future , then how does time pass ? also , if past events are unreal , then what do photographs actually show ? and what are we referring to when we talk about past events ? these issues have led some to prefer the eternalist theory of time .
one question that is relevant here is whether time travel is permitted by the prevailing laws of nature . this is presumably a matter of empirical science ( or perhaps the correct philosophical interpretation of our best theories from the empirical sciences ) . but a further question , and one that falls squarely under the heading of philosophy , is whether time travel is permitted by the laws of logic and metaphysics . for it has been argued that various absurdities follow from the supposition that time travel is ( logically and metaphysically ) possible . here is an example of such an argument .
if the word
time
were a member of this large class , then by drawing attention to use , to ordinary ways of using the word
time ,
wittgenstein would expect that we will be able to dissolve rather than answer most of our philosophical questions . unfortunately , the word
time
probably is not a member of the large class that wittgenstein is speaking of , and even if it were , most philosophers want to know much more than what
time
means . philosophers of time are usually not interested in precisely defining the word but rather are interested in what time ' s important characteristics are and in resolving philosophical disputes about time that do not seem to turn on what the word means . for one example , they want to know about the relationship between the manifest image and the scientific image of time . for a second example , when newton discovered that the fall of an apple and the circular orbit of the moon were both caused by gravity , this was not a discovery about the meaning of
gravity ,
but rather about what gravity is . do we not want some advance like this for time ?
buddhism also teaches that the present reality is the only reality , and attaches supreme importance to it . as the buddha says in the bhaddekaratta sutta : “you shouldn’t chase after the past or place expectations on the future . what is past is left behind . the future is as yet unreached . whatever quality is present you clearly see right there , right there . ” there are also buddhist philosophers who have formulated a kind of buddhist presentism . one of them , fyodor shcherbatskoy wrote : “everything past is unreal , everything future is unreal , everything imagined , absent , mental… is unreal… ultimately real is only the present moment…”
discussions of the nature of time , and of various issues related to time , have always featured prominently in philosophy , but they have been especially important since the beginning of the 20th century . this article contains a brief overview of some of the main topics in the philosophy of time — fatalism ; reductionism and platonism with respect to time ; the topology of time ; mctaggart ' s arguments ; the a theory and the b theory ; presentism , eternalism , and the growing universe theory ; time travel ; and the 3d / 4d controversy — together with some suggestions for further reading on each topic , and a bibliography .
the first answer is that tenses represent objective features of reality that are not captured by eternalism and the block - universe approach . this philosophical theory is said to
take tense seriously
and is called the tensed theory of time . the theory claims that when we learn the truth - values of certain tensed sentences we obtain knowledge that tenseless sentences do not and cannot provide , for example , that such and such a time is the present time—that it is now noon . tenses are almost the same as what is represented by positions in mctaggart ' s a - series , so the theory is commonly called the a - theory of tense .
( 2 ) advocates of a growing - past agree with the presentists that the present is special ontologically , but they argue that , in addition to the present , the past is also real and is growing bigger all the time . c . d . broad , george ellis , richard jeffrey , and michael tooley defend the growing - past theory . william james famously remarked that the future is so unreal that even god cannot anticipate it . it is not clear whether aristotle accepted the growing - past theory or accepted a form of presentism ; see hilary putnam ( 1967 , p . 244 ) for commentary on this issue .
the special theory of relativity ( str ) doe not assume that all frame of reference are equally ontologically privileged , rather it cannot assess a privileged frame . this is an important distinction as an eternal block conception of time does not follow from str ! rather , str is agnostic on eternalism or presentism or growing block , as it cannot know if all frames are ontologically privileged , or if there is a single frame that is absolute . it is an epistemic problem , and one should not assume that str means
all frames are equally ontologically privileged
, as that claim would be an argument from ignorance fallacy right from the get - go .
a philosophical introduction to conceptual questions involving space and time . suitable for use as an undergraduate textbook without presupposing any other course in philosophy . there is a de - emphasis on teaching the scientific theories , and an emphasis on elementary introductions to the relationship of time to change , the implications that different structures for time have for our understanding of causation , difficulties with zeno’s paradoxes , whether time passes , the nature of the present , and why time has an arrow . the treatment of time travel says , rather oddly , that time machines “disappear” and that when a “time machine leaves for 2101 , it simply does not exist in the intervening times , ” as measured from an external reference frame .
all three ontologies [ namely , presentism , the growing - past , and eternalism ] imply that , at the present moment , we only ever experience a part of the present and that we do not have direct access to the past . they all agree that nothing exists now that is not present . they all need to show somehow that there is an important difference between never existing ( santa claus ) and not still existing ( abraham lincoln ) . members of all three camps will understand an ordinary speaker who says , “there will be a storm tomorrow so it’s a good thing we fixed the roof last week , ” but they will have different treatments of this at a metaphysical level .
members of the a - camp often say that mctaggart ' s a - theory is the fundamental way to view time ; events are always changing as they move farther away from the present , the now is objectively real and so is time ' s flow ; ontologically we should accept either presentism or the growing - past theory ; predictions are not true or false at the time they are uttered ; tensed facts are ontologically fundamental rather than untensed facts ; and the ontologically fundamental objects are 3 - dimensional , not 4 - dimensional . [ all these ideas will be explained in more detail later . ] persons are considered members of the a - camp if they accept a majority of the above claims .
the more classical approach to temporal logic , however , does not add implicit premises to arguments formalized in classical predicate logic as we have just been doing . the classical approach is via tense logic , a formalism that adds tense operators on propositions of propositional logic or predicate logic . a . n . prior was the pioneer in the late 1950s . michael dummett and e . j . lemmon also made major , early contributions to tense logic . prior created this new logic to describe our reasoning involving time phrases such as “now , ” “happens before , ” “twenty - three minutes afterwards , ” “at all times , ” and “sometimes . ” he hoped that a precise , formal treatment of these concepts could lead to resolution of some of the controversial philosophical issues about time .
presentism is a theory in philosophy which says that the only events and objects which exist are those that exist in the present . so , only things which exist now , right now , really exist . it is a theory which focuses on the temporal present ; that is , things existing in the present moment . it is not a theory concerned with whether things exist somewhere else . so long as that object or event which is spatially distant from us exists in the present moment , then it exists . if we were to make a list of all the things that a presentist believes exists and does not exist ; in the list of things that do exist we would have : the grand canyon and the taj mahal ; whereas in the list of things that do not exist we would have : socrates and tomorrow’s events .
the counter from the defenders of eternalism and the block - universe is that , regarding ( i ) , the vividness of here does not imply the unreality of there . regarding ( ii ) and the open future , the block theory allows determinism and fatalism but does not require either one . eventually there will be one future , regardless of whether that future is now open or closed , and that is what constitutes the future portion of the block . finally , don ' t we all fear impending doom ? but according to presentism and the growing - block theory , why should we have this fear if the doom is known not to exist , as these two kinds of theorists evidently believe ? the best philosophy of time will not make our different attitudes toward future danger and past danger be so mysterious , says the eternalist .
some objects last longer than others . they persist longer . but there is philosophical disagreement about how to understand persistence . objects considered four - dimensionally are said to persist by perduring rather than enduring . think of events and processes as being four - dimensional . the familiar three - dimensional objects such as chairs and people are usually considered to exist wholly at a single time and are said to persist by enduring through time . advocates of four - dimensionalism endorse perduring objects rather than enduring objects as the metaphysically basic entities . all events and processes are four - dimensional sub - blocks of the block - universe . the perduring object persists by being the sum or “fusion” of a series of its temporal parts ( also called its temporal stages and temporal slices and time slices ) . for example , a thirty - five - year old man can be considered to be a four - dimensional perduring object consisting of his childhood , his middle age and his future old age . these are three of his infinitely many temporal parts .
one suggestion from proponents of the multiverse theory is that the reason why our universe exists with time and with the particular laws it has is that every kind of physically possible universe exists . our single universe exists by means of a random selection process , by a process in which any physically possible universe inevitably arises as an actual universe , in analogy to how continual re - shuffling a deck of cards inevitably produces any possible ordering of the cards . to improve the analogy , one should suppose that there is no supernatural shuffler involved . there are related issues of philosophical interest . one is what it means to be physically possible if the laws of a multiverse can be different from ours since the term
physically possible
means
allowed by the laws of nature .
a second is whether every universe that can exist really does . a third is how the multiverse theory is related to modal realism in which every universe that is logically possible actually exists . for an introduction to the various multiverse theories without considering the related issues just mentioned , see ( krauss , 2012 , pp . 170 and 206 ) .
one of the major issues for presentism is how to ground true propositions about the past . what makes it true that u . s . president abraham lincoln was assassinated in 1865 ? in technical - ease , we are asking what are the
truthmakers
of the true propositions and the
falsemakers
of the false propositions . many presentists say past - tensed truths lack truthmakers in the past but are nevertheless true because their truthmakers are in the present . they say what makes a tensed proposition true are only features of the present way things are , perhaps traces of the past in pages of present books . the eternalist disagrees . when someone says truly that abraham lincoln was assassinated , the eternalist and the growing - past theorist believe this is to say something true of a real abraham lincoln who is not present . the block theorist and the growing - block theorist might add that lincoln is real but far away from us along the time dimension just as the moon is real but far away from us along a spatial dimension . why not treat these distant realities in the same manner , they ask ?
there is an ongoing philosophical dispute about the extent to which there is an element of conventionality in einstein’s notion of two separated events happening at the same time , an issue discussed a few paragraphs ago . the philosopher hans reichenbach said that to define simultaneity in a single reference frame in special relativity you must adopt a convention about how fast light travels going one way as opposed to coming back ( or going any other direction ) . he recommended adopting the convention that light travels the same speed in all directions ( in a vacuum free of the influence of gravity ) . he claimed it must be a convention because there is no way to measure whether the speed is really the same in opposite directions since any measurement of the two speeds between two locations requires first having synchronized clocks at those two locations , yet the synchronization process will presuppose whether the speed is the same in both directions . the philosophers b . ellis and p . bowman in 1967 , and d . malament in 1977 , gave different reasons why reichenbach is mistaken . once again , this discussion presumes special relativity and not general relativity . for an introduction to this dispute , see the frequently asked questions . for more discussion , see ( callender and hoefer 2002 ) .
based on what you pointed out as problems for the theory , i think you dont quite fully grasp the concept of presentism .
if time passes
, you say , but that time does not
pass
is the basis of the theory in the first place . first , remember you shouldn ' t favor either one of these theories just realize that neither can be distinguished or
proven
. okay , before i move on to a presentist point of view , i want to make some objective statements : what you call past are memories created in your head in the present . what you call future are dreams created in your head in the present . what you call experience is based on what you have created in your head as a model of
reality
. so if you are incredulous , you acknowledge that whether the past existed or not ( also whether the future will exist or not ) , it is based on a thought in your head . now i think it is easy to see the difference in the two theories : one , the past really happen or two , its an imagination in the eternal present . impossible to distinguish these theories with any tests or logic , thus the existence of the two theories .
note : this entry does not discuss the consciousness , perception , experience , or phenomenology of time . an historical overview and general presentation of the various views is available in the entry on temporal consciousness . further coverage can be found in the sep entry on the experience and perception of time . for those interested specifically in phenomenological views , see the entries on husserl ( section 6 ) , and heidegger ( section 2 : being and time ) .
a good deal of work in the philosophy of time has been produced by people worried about fatalism , which can be understood as the thesis that whatever will happen in the future is already unavoidable ( where to say that an event is unavoidable is to say that no human is able to prevent it from occurring ) . here is a typical argument for fatalism .
there exist now propositions about everything that might happen in the future . [ 1 ]
if ( 1 ) and ( 2 ) , then there exists now a set of true propositions that , taken together , correctly predict everything that will happen in the future .
if there exists now a set of true propositions that , taken together , correctly predict everything that will happen in the future , then whatever will happen in the future is already unavoidable .
the main objections to arguments like this have been to premises ( 2 ) and ( 4 ) . the rationale for premise ( 2 ) is that it appears to be a fundamental principle of semantics , sometimes referred to as the principle of bivalence . the rationale for premise ( 4 ) is the claim that no one is able to make a true prediction turn out false .
a proper discussion of fatalism would include a lengthy consideration of premise ( 4 ) , and that would take us beyond the scope of this article . for our purposes it is important to note that many writers have been motivated by this kind of argument to deny bivalence . according to this line , there are many propositions — namely , propositions about matters that are both future and contingent — that are neither true nor false right now . take , for example , the proposition that you will have lunch tomorrow . on this view , that proposition either has no truth value right now , or else has the value indeterminate . when the relevant time comes , and you either have lunch or don ' t , then , on the view in question , the proposition that you have lunch on the relevant day will come to be either true or false ( as the case may be ) , and from then on that proposition will forever retain its truth value . [ 2 ]
the view that bivalence is false , and that , in particular , there are sometimes propositions about the future that are neither true nor false , is sometimes referred to as the “open future” response to arguments for fatalism . one important presupposition of the open future response is that it makes sense to talk about a proposition ' s having a truth value at a time , and that , moreover , it is possible for a proposition to have different truth values at different times . thus , the open future response to arguments for fatalism entails the following semantical thesis .
the fundamental semantical locution is ‘ p is v at t ’ ( where the expression in place of ‘ p ’ refers to a proposition , the expression in place of ‘ v ’ refers to a truth value , and the expression in place of ‘ t ’ refers to a time ) .
it is possible for a proposition to have different truth values at different times .
the fundamental semantical locution is ‘ p is v ’ ( where the expression in place of ‘ p ’ refers to a proposition and the expression in place of ‘ v ’ refers to a truth value ) .
it is not possible for a proposition to have different truth values at different times .
other views that have ( at least sometimes ) been associated with the open future response to fatalism include taking tense seriously and the growing universe theory , which will be discussed below .
suggestions for further reading : aristotle , de interpretatione , ch . 9 ; besson and hattiangadi forthcoming ; lewis 1986a ; markosian 1995 ; mccall 1994 ; miller 2005 ; sullivan forthcoming ; taylor 1992 , ch . 6 ; torre 2011 ; van inwagen 1983 , ch . 2 .
if the answer to this last question is yes — if it is possible for there to be a period of time during which nothing changes , anywhere ( except , perhaps , for the pure passage of time itself , if there is such a thing ) — then it is possible that a worldwide “freeze” will occur between the time you finish reading this sentence and the time you start the next sentence . in fact , if it ' s possible for there to be a period of time without change , then it may well be that a million years have passed since you finished reading the last sentence .
the question of whether there could be time without change has traditionally been thought to be closely tied to the question of whether time exists independently of the events that occur in time . for , the thinking goes , if there could be a period of time without change , then it follows that time could exist without any events to fill it ; but if , on the other hand , there could not be a period of time without change , then it must be that time exists only if there are some events to fill it .
aristotle and others ( including , especially , leibniz ) have argued that time does not exist independently of the events that occur in time . this view is typically called either “reductionism with respect to time” or “relationism with respect to time , ” since according to this view , all talk that appears to be about time can somehow be reduced to talk about temporal relations among things and events . the opposing view , normally referred to either as “platonism with respect to time” or as “substantivalism with respect to time” or as “absolutism with respect to time , ” has been defended by plato , newton , and others . on this view , time is like an empty container into which things and events may be placed ; but it is a container that exists independently of what ( if anything ) is placed in it .
why would someone endorse the reductionist view about time ? historically , two main arguments have played the biggest roles in convincing people . one is conceptual : time , according to this argument , is by definition nothing more than a system of temporal relations among things and events , so that the idea of a period of time without change turns out to be incoherent . the other main argument for reductionism is epistemological : we could never have any reason , according to this argument , to posit a period of empty time ; and , moreover , even if there were such a period , we would not have any way of knowing about either its existence or its length .
what about platonism with respect to time — why would someone endorse that view ? one reason is that the empty container metaphor has a lot of intuitive appeal . ( this is no doubt true of both the temporal and spatial versions of platonism . ) and another reason is that some people do not find the main arguments against platonism with respect to time compelling . for example , it has been suggested by sydney shoemaker that there are possible circumstances in which it would make perfect sense to posit periods of empty time , and even to claim to know just how long those periods are .
here is a simplified version of shoemaker ' s argument . consider a small , spatially finite possible world that is divided into three zones , a , b , and c . in zone a , there is a complete freeze — a cessation of all change — for one hour every 2 years . these local freezes in zone a are preceded by a short period in which every object in a takes on a reddish glow ( observable to the occupants of all three zones ) , while at the same time a temporary force field develops at the boundary of zone a , preventing anything from entering or exiting that zone during the freeze . while the freeze in zone a is taking place , zone a appears to those in zones b and c to be pitch black , since no light can enter or exit the frozen zone ; but as soon as the local freeze in zone a is over , the people in the other two zones can again see everything in zone a , and can in fact see those things resuming their normal behaviors without missing a beat . to those who remain in zone a for the freeze , it appears that the reddish glowing and the development of the force field are immediately followed , not by any cessation of change , but , instead , by a large number of sudden and discontinuous changes in the other two zones .
meanwhile , in zone b there is a similar freeze for one hour every 3 years , and in zone c there is a freeze for one hour every 5 years . the inhabitants of this strange world quickly become aware of the local freezes , and they have no trouble calculating the “freeze function” for each of the three zones . what ' s more , they also calculate that there is a global freeze — a period during which each one of the three zones undergoes a local freeze — exactly once every 30 years . whenever a global freeze occurs , of course , no one is able to see any frozen objects or blacked - out zones , since everyone and everything is frozen at the same time . but the reddish glowing and the development of temporary force fields that precede each world - wide freeze are observable to everyone ; and so the global freeze times come to be celebrated by “empty time parties” all over the world .
no doubt the inhabitants of this unusual world could come up with a theory that explains the local freezes in a way that doesn ' t posit any empty time . for they could theorize that in zone a there is a local freeze every two years , except for the 30th year , when there is no freeze ; and similarly for the other zones . but such a theory would involve freezing functions that are more complicated than those that entail a global freeze every 30 years .
what is this thought experiment supposed to show ? well , it can ' t be taken to show that global freezes are possible , because ( at least the way the story has been told here ) they are simply a stipulated detail of the story , and we can ' t show that something is possible merely by stipulating that it is the case in some possible world . what the thought experiment does seem to show , however , is that it is possible for rational beings to have at least some evidence for the existence of periods of empty time in their world . for we can describe the possible world of the thought experiment in a neutral way that specifies how things in the world appear to its denizens , without specifying whether the real freeze functions for zones a , b , and c are the simpler ones described above that entail a global freeze every 30 years or the more complicated ones that do not have that entailment . and a possible world that appears this way to its inhabitants is surely a world in which those inhabitants have some reason to take seriously the possibility that there are periods of empty time in their world , that they know when those periods occur , and even that they know exactly how long the periods of empty time last .