More Objections to Identity Theory

In his article, Smart considers a number of different objections to the Identity Theory. We've already looked at some objections that make illegitimate appeals to Leibniz's Law. Here are Smart's replies to some of the other important objections:

Objection 3: Even if sensations are brain processes, still, they have peculiar mental properties, and these properties are not just physical properties

Smart replies by analyzing mental concepts in a way that does not make any commitment to whether the conceived states are physical or non-physical. He says that the meaning of mental concepts (including sensation concepts) is topic-neutral. It leaves it an open question whether the mental states are identical to processes in the brain, or to procesess taking place in Cartesian souls, or to some other sort of process. So the present objection has a grain of truth: the concept of a sensation is not the concept of something that has to be physical.

As we saw before, though, Smart does think that, as a matter of fact, the mental states are processes in the brain. So the present objection has a grain of falsehood: sensations are in fact identical to brain processes. Scientific investigation and considerations of simplicity show this to us. It's just that one won't be in a position to know that mental states are brain processes simply by virtue of understanding mental concepts.

What is Smart's topic-neutral analysis of mental concepts? Here is one of Smart's sample analyses:

I have an orangish visual experience = There is something going on in me which is like what is going on when ...
The "..." is filled in with a description of the stimuli that standardly cause orangish experiences. For example: " what is going on when I have my eyes open, and there is an orange object in front of me, lit by good light." So Smart analyzes sensations in terms of (i) what the normal stimulus is, and (ii) a similarity between one's present experience and the experience one has when stimulated in that normal way. The analysis leaves the underlying nature of this similarity unspecified. In Smart's view, all orangish visual experiences will all be similar because they are brain processes of the same neurological type. In a dualist's view, they will all be similar because they are the same sort of immaterial process. The analysis of the concept of orangish visual experiences does not take a stand on which of those alternatives is correct. That is something for scientific investigation to uncover.

Armstrong and Lewis and the functionalists also want to analyze mental concepts in topic-neutral terms. They will improve on these analyses of Smart's in three ways:

  1. They get rid of the appeal to similarity, and analyze mental concepts only in terms of causes and effects
  2. They analyze mental concepts not just in terms of their causes (stimuli), but also in terms of their effects
  3. They analyze mental concepts not just in terms of their external causes and effects, but also in terms of what other mental states the conceived states tend to cause and be caused by.
Objection 4: My after-image is orangish, and nowhere in physical space. However, my brain processes all take place in physical space, and none of them are orangish. So my after-image cannot be identical to any of my brain-processes.
Smart replies by asking us to distinguish between:
  • experiential states, or other mental states
  • mental objects
The after-image, if it existed, would be a mental object. The corresponding mental state would be the state of experiencing an orangish after-image.

Smart does not propose to identify the mental object (the after-image) with any brain process. Rather, he identifies the state, experiencing an orangish after-image, with some brain process. So the present objection does not apply. It is true that the brain process takes place somewhere in the brain, and is not orangish. But the state of experiencing an orangish after-image is not itself orangish; and it may very well take place somewhere in the brain.

Similarly with pain: when you have a pain in your leg, the state of being in pain isn't in your leg. It's this state, not some mental object--the pain--that the identity theorist wants to identify with a state of your brain.

What should an identity theorist say about the after-images and the pains themselves? Most identity theorists will say that there is no really existing objects that the words "after-image" and "pain" refer to. There are people who are in a certain state, the state we call "having pain," but there are no special objects, pains. (Compare the way some materialists treat the expression "the mind.")

Consider the following expression: "there is a table in my mind." It's ambiguous. It could mean:

  1. I'm thinking of a table; I'm having some thought which is about the table, which represents the table.
Or it could mean:
  1. There is a table literally in my mind; the table is a part or component of my mind. (This is presumably false.)
Similarly, "there is an orangish after-image in my mind" could mean one of two things. It could mean:
  1. I'm having a certain sort of experience, one which is caused by staring at a bright light for too long, and which represents a glowing orange ball of light floating 3 feet in front of me.
Or it could mean:
  1. There is literally some orangish mental object which is a part or component of my mind.
The Identity Theorist says that when you experience an orangish after-image, (iii) is true but not (iv). There are no things, after-images. Rather, to say you have an after-image or that there's an after-image in your mind is just to talk about what kind of experiential state you're in. You're in an experiential state that represents some glowing orange ball of light. Some experiences, like this one, simply represent things which aren't there.

Similarly, the Identity Theorist will say that there are no things, pains. Talk about pains is just a misleading way of talking about states that feel bad.

Objection 6: We have privileged epistemic access to our sensations. It is not possible for someone else to be in a better position than you are, to know what sensations you're having. Yet if Smart's Identity Theory were correct, it seems that it should be possible for someone to learn the identities, and, by observing your brain, come to be in a better position than you are to know what sensations you're having. This shows that Smart's Identity Theory is absurd.
Smart's reply is very brief. He seems amenable to our discovering more exact evidence for when another person is in pain, which would enable us to overrule the person's own judgment about whether he is in pain.


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