Part 6 paragraph 4:

The classical identity theory holds that each token mental state (in a particular person’s mind at a particular time) is identical with a token brain state (in that person’s brain at that time). A stronger materialism holds, instead, that each type of mental state is identical with a type of brain state. But materialism does not fit comfortably with phenomenology. For it is not obvious how conscious mental states as we experience them—sensations, thoughts, emotions—can simply be the complex neural states that somehow subserve or implement them. If mental states and neural states are simply identical, in token or in type, where in our scientific theory of mind does the phenomenology occur—is it not simply replaced by neuroscience? And yet experience is part of what is to be explained by neuroscience.

What is the difference between a token of mental state vs its type?


  • It is not "obvious" how objects we see can be assemblies of atoms and molecules, or how warmth we experience can be their Brownian motion. Physical models do not have to "fit comfortably" with phenomenology, they just have to model the phenomena. The identity means that we are dealing with the same underlying states accessed and described in different ways. In type theory a systematic redescription between mantal and physical is assumed to be possible for entire classes of states, while in the token theory only on individual basis.
    – Conifold
    Commented Feb 24, 2023 at 18:47
  • Can you please why the later theory leads to a stronger materialism
    – PDT
    Commented Feb 24, 2023 at 19:50
  • Because type identity implies token identity, but not vice versa, see IEP. It would also make for a more comprehensive physical theory of mental states because it entails existence of general descriptions of neural correlates for various types of them, belief, doubt, intention, fear, joy, etc.
    – Conifold
    Commented Feb 24, 2023 at 20:40
  • But I can’t fathom why token identity theory would not imply type identity. Let’s say every token of doubt had a brain state that correlates to it, doesn’t this mean that the type of category which each of these categories belong correlates with a category of a brain state? For example if I said that the arms legs body and head of a cat is made of matter then surely the entire cat is material?
    – PDT
    Commented Feb 27, 2023 at 11:26
  • 1
    A token of doubt in one person in one context may correlate to a brain state that has nothing in common with brain states that correlate to doubt in another person, or even in the same person in another context. So no general description of brain states correlated to doubt exists, i.e. there is no doubt-type of brain states, and type-type identity fails. This is called "multiple realizability" of mental by physical, and it is a major objection to the type identity theory, see SEP.
    – Conifold
    Commented Feb 27, 2023 at 11:45

1 Answer 1


A token is a particular instance of a type. So if a type of brain state is 'worried', say, then you might experience many different worries. If at a given instant you are worried about one specific thing, that would be a token worried state.

  • A stronger materialism holds, instead, that each type of mental state is identical with a type of brain state. Could you then explain why it is a stronger materialism, thanks?
    – PDT
    Commented Feb 24, 2023 at 13:31
  • @PDT Because then complete knowledge of the brain amounts to complete description of one's mental states. Moderate materialistic theories would instead insist that, for example, although we know about one's mental states only thanks to them being identical with states of the brain and thus affecting us causally (via speech, for example) we can only know them in a process of interpretation (Davidson) or by taking an intentional stance (Dennett) which is another mode of description, another set of concepts which describe the same tokens although in a mannor incommensurable with neurology. Commented Mar 20 at 23:13
  • @PDT This might seem insignificant, but Davidson, for example, argues in his Mental Events that this incommensurability means that there exist no deterministic laws of the mental because ascribing someone a mental state involves interpretation or, in other words, rationalization. We don't rationalize nature, but we try to make sense of eachother in dialogue. Thus the materialism of Davidson means that this process is possible in relation to humans only thanks to certain features of the physical stuff we're made of but these features aren't the same as our mental characteristics. Commented Mar 20 at 23:18
  • @PDT This implies that the human sciences have autonomy from the natural sciences. They differ not only in complexity (positivism) but also in fundamental method (hermeneutics). Commented Mar 20 at 23:19

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