Mind-Brain Identity and the Nature of States

Abstract

According to what I will call the ‘Identity Thesis’, a human’s psychological states are identical with states of or in her brain. Psychological properties, such as being in pain, believing that water is wet, or desiring ice cream are, on this view, neurological properties. Proponents of this view, such as David Lewis and David Braddon-Mitchell and Frank Jackson, admit that the Identity Thesis is costly, since it entails that beings with relevantly different nervous systems than ours, or without such systems at all, cannot share our psychological states, no matter how sophisticated their behaviour might be. But, they insist, this cost is worth paying. For, they contend, accepting it is the only way to guarantee that human psychological properties are causally efficacious. I believe that this analysis of the costs and benefits is mistaken. I will argue, first, that the costs are higher than admitted since the view implausibly entails that the subjects of psychological states are neurones or brains. I will then argue that the advertised benefit is not delivered. There is, I will argue, little reason to anticipate discovering a neurological property of the kind advertised. Seeing all of this will require getting a bit clearer on what a state is, and on what it is to affirm identity in the case of states. For the initial allure of their view rests, I think, on various confusions about the nature of states.