That the mind is a purely physical substance.

Re: Continuity of Identity Through ChangeBy bringing up this argument, Philocristos has brought up a huge worthy discussion on its own - Personal Identity Theory. I am going to endorse a view known as the Psychological Approach. To start with let's look at the nature of a person and what distinguishes personal identity from any other Ontology - in other words, why can't Plato just it is something that participates the form of person? Or why can't Aristotle simply make reference to four causes? The key difference to note here is that, immaterial or not, a person has something that an ordinary object does not - consciousness. Philocristos has argued that physcialism implies that one subscribes to a view that holds the body to be key to Personal Identity, and proceeded to show problems with this by giving a twist on the classis "Ship of Theseus" thought experiment. What this thought experiment fails to understand in this case however, is the special features that apply to Personal Identity Theory over regular Ontology - specifically, consciousness. Consider the case of recent events inthe Spider-Man comics, given that perhaps not everyone is as nerdy as I am suppose I should explain. Doctor Octopus had a terminal illness, and not wanting to die, he switched consciousness with Spider-Man, leaving Parker's consciousness to die (at least for the moment) in the body of one of his greatest foes. In this example, Parker and Ock have not switched brains, but merely consciousness (characters in the Marvel universe do have souls) - the key question that we wish to answer is who survived, and who died. Looking at the reaction to the comic, it seems clear that there is no debate about how survived and who died - Pete died, Ock lived. The reason we say this is because Doctor Octopus in Peter Parker's body has the consciousness, and psychology of Doctor Octopus. This does not prent a challenge to physicalism however, because the identity of a person, regardless of whether or not that person is physical, can still be rooted in consciousness, rather than in the brain. To further illustrate the weakness of the soul theory of personal identity, consider a thought experiment by John Locke - imagine, that when you went to sleep last night, God replaced your soul. This soul is a completely new soul, but has the same memories, beliefs and abilities as the old soul. Consider this taken even further, that for every second which passes your life, God replaces your old soul with a new one, each with the same memories, beliefs and abilities as the old one. Here we have the soul theory, advocating that it is possible that we can not even be the person we were one second ago. Can we seriously uphold this? Common sense says no, the soul theory says yes.Re: The indiscernability of identicalsConsider the following premises.P1 - If one were to have a perfect understanding of the brain, then so too would one have a perfect understanding of the mind.I will not support this further, it follows from the Physcialist viewpoint.P2 - Different language can be used to describe the same thing, and the usage of the different language will affect linguistic consequences.I can describe Venus as either the morning star, or the evening star - but they are both Venus. Still, I can say things about the morning star that I cannot say about the evening star.With these two premises, we can refute 1-4.1 - In theory, the brain could be subject to first person observation, were we to have perfect knowledge of the brain. In other words, with this perfect knowledge we would understand the conscious experience of the person whose brain it is.2 - This is clearly a linguistic difference, the mind refers to the conscious experience of the brain. Were our language different the part of the brain experiencing thought would be acknolwedged as equivalent to that thought and could therefore be about it.3 - Yes, there is an image of a green sweater being processed through the brain as a mental state.4 - Yes, the emotion does have a mass and chemical composition.Point 5 is an entirely different debate (i.e. about whether or not it is possible for an immaterial substance to experience consciousness). For what it is worth, I do not think that one's mind can exist independantly of the brain or vice versa. This is a serious position and I refer you to the Philpapers survey where "Conceivable, but not metaphysically possible" was the most common response to the issue of philosophical zombies[1].Re: Argument from Intentional ActionThe idea that because physicalism implies that because the mind and brain are in a way the same it therefore implies that mental states cannot influence physical states is downright silly. It should be plainly obvious that a part of something can influence the thing of which it is a part (e.g. The Sun is a part of the solar system, and can influence the solar system). Just because mental states are a part of the brain does not mean that they cannot influence other parts. Remember, I have argued earlier that mental states are equivalent to the brain states to which they correspond, so problem here.Re: The Argument from ReasonThe first premise here is false. Philocristos has argued that because physicalism implies that our beliefs are the result mechanistic processes and mechanistic processes do not give rise to reason then our beliefs cannot be rational. This is a very trippy argument, but it makes a very fast leap from physics to chemistry to biology. It is clear that physical laws themselves are not rationl processes, but they do give rise to life.The important thing to note then is evolutionary theory, whatever characteristics of a lifeform are most likely to lead to its survival and reproduction will be the ones that are most likely to be passed on. I do not even think it up for discussion that a creature will be more likely to survive and reproduce if it can form rational beliefs than if it can't (e.g. When hunting it would take use of reason to decide how and whether or not we should kill a mammoth).References: 1 - http://philpapers.org...