Over at the Philosophy of Brains blog, Richard Brown has a post called “Kripke, Consciousness, and the ‘Corn” in which he tries to defend Higher-Order Representational theories of consciousness against the Unicorn Argument, by wedding HOR to a Kripkean causal theory of reference.
By amazing coincidence, I have a new version of “Beware of the Unicorn” up on my website now which contains a section dealing with exactly this sort of move. I discuss this under the heading of combining HOR with a so-called “direct” theory of reference.
The direct reference hypothesis (DR) holds that there are certain mental representations such that (a) two or more of these representations are about the same object if and only if they have the same cognitive significance and (b) these representations have representational content only if that which they represent exists. The most promising aspect of DR with respect to defeating the Unicorn is (b). Combining HOR (Higher-Order Representational theory of consciousness) with DR entails postulating that all of the higher order representations relevant to explaining consciousness have representational content only if the states they are representations of exist. If HOR could be combined with DR it would be immune to the Unicorn.
However, at least in the case of HOT (Higher-Order Thought theory of consciousness), HOR cannot be plausibly combined with DR. This is due to troubles that arise in connection with part (a) of DR. When we examine the most plausible examples of attributions of consciousness-conferring higher-order thoughts, we find that they give rise to opaque contexts inconsistent with DR.
To see these points, consider an example. Suppose that Jones has some mental state that is a candidate for state consciousness. Suppose, then, that Jones sees that x is red. In order for the state of Jones seeing that x is red to be a conscious state, according to HOT, Jones must have a higher-order thought about that state. It is useful to consider what attributions of that thought would look like. We might attribute the HOTs by saying that
(1) Jones believes that he sees that x is red.
(2) Jones believes of himself that he sees that x is red
Either way, by the time we get to â€œhe sees that x is redâ€ we are well into an opaque context.
Suppose that seeing that x is red is identical to having neural activity pattern number 67 in area v4 of cerebral cortex. Consider that if we replace â€˜sees that x is redâ€™ in (1) and (2) with â€˜has activity 67 in area v4â€™ then we wind up with sentences that may very well have the opposite truth values of (1) and (2). This is not because seeing that x is red is not identical to having activity 67 in area v4. This is because Jones may very well lack appropriate neurophilosophical sophistication to believe of himself that he has activity 67 in area v4. DR requires the intersubstitutability salvae veritate of co-referring terms for the alleged relata. If the defender of transparent HOTs were to insist on the possibility of the above substitutions as salva veritate, then the following problem arises. If the meaning of a term is purely referential, and HOTs determine what it is like, and â€˜sees that x is redâ€™ and â€˜has activity 67 in area v4â€™ are co-referring, then Jonesâ€™s perceptual experiences would seem to him to be the neural activity pattern 67 in area v4. I suppose, however, that while Paul Churchland’s experiences may seem neural to Paul Churchland, Jonesâ€™s experiences need not seem neural to Jones.
Perhaps a different way of attempting to wed HOT and DR is by construing consciousness-conferring higher-order thoughts as referring demonstratively. Such a construal would entail that Jones’ state of seeing x as red is conscious only if Jones has a Higher Order demonstrative thought expressible by “this is a state of seeing that x is red” where the demonstrative “this” refers, if at all, to a state Jones actually has. If the demonstrative “this” fails to refer, then “this is a state of seeing that x is red” fails to express a consciousness-conferring higher order thought because it fails to express any thought.
One consequence of a direct reference theory of demonstrative thoughts is that any difference in reference of â€œthisâ€ gives rise to differences in thought. Two occasions of thoughts expressible by â€œthis is an umbrellaâ€ would be occasions of thoughts with different contents if the two occasions of the demonstrative â€œthisâ€ referred to numerically distinct umbrellas. We might summarize this point by saying that directly referring demonstrative thoughts are object-involving.
The object-involvement of demonstrative thoughts does not fit well with the HOT theory. The main problem arises because, on Rosenthalâ€™s HOT theory, the contents of HOTs are supposed to be responsible for determining what itâ€™s like to have conscious states.
Rosenthal states the relation between HOT and what it is like as follows:
What itâ€™s like for one to be in a qualitative state is a matter of how one is conscious of that state. If I am conscious of myself as having a sensation with the mental quality red, that will be what itâ€™s like for me, and similarly for every other mental quality. And how we are conscious of our qualitative states is a matter of how our HOTs characterize those states. There being something itâ€™s like for me to be in a state with a particular mental quality is a matter of my having a HOT that characterizes a state I am in as having that mental quality. (D. Rosenthal, Consciousness and Mind, p. 186.)
In other words, what itâ€™s like to be in a conscious state is one and the same as how oneâ€™s state appears to one. Further, how the state appears to one is a matter of how the state is represented by a higher-order thought.
The appearance-determining aspect of consciousness-conferring higher-order thoughts is the aspect that makes them so poorly modeled by demonstrative thoughts. Mere numerical differences can suffice to give rise to differences in demonstrative reference. However, mere numerical differences do not suffice to give rise to differences in appearance.
My physical doppelganger who lived on a physical doppelganger of the planet I live on, with a physically similar life history would, I take it, have conscious states such that what it is like for him to be in those states is like what it is like to be in mine. His object-involving thoughts, however, would differ from mine insofar as his â€˜thisâ€™â€™s pick out a distinct umbrella from mine, his â€˜hereâ€™â€™s distinct places, his â€˜Iâ€™â€™s a distinct person. But just as his umbrella may very well appear just as my umbrella does, so will his lower-order mental states appear to him as mine do to me. Thus, in spite of diverging in the contents of our demonstrative higher-order thoughts, what itâ€™s like to be me may very well be just like what itâ€™s like to be my physical doppelganger.