I was asked to review the Bloomsbury Companion to the Philosophy of Consciousness and had some things to say about the chapter on higher-order theories of consciousness by Rocco Gennaro that I could not fit into a paragraph or two so I am extending them here.

In the fourth paper of this second section Rocco Gennaro gives us his interpretation of “Higher-Order Theories of Consciousness”. Higher-order theories of consciousness claim that consciousness as we ordinarily experience it requires a kind of inner awareness, an awareness of our own mental life. To consciously experience the red of a tomato is to be aware of oneself as seeing a red object. Gennaro offers a survey of the traditional higher-order accounts but anyone reading this chapter who was new to the area would get a very biased account of the lay of the land. Specifically there are three things that are misleading about Gennaro’s overview.  The first is how he presents the theory itself. The second is how he responds to the classic misrepresentation objection to higher-order thought theories of consciousness. And the third is in presenting the case for whether or not the prefrontal cortex is a possible neural realizer of the relevant higher-order thoughts.

Gennaro interprets the higher-order theory as what I have called the ‘relational view’. As he says on page 156,

Conscious mental states arise when two unconscious mental states are related in a certain specific way, namely that one of them (the [higher-order representation]) is directed at the other ([mental state]).

This makes it clear that on his way of doing things it is necessary that there be two states, with one directed at the other and that these two states together ‘give rise’ to a (phenomenally) conscious mental state. Rosenthal and those who follow him interpret the higher-order thought theory as what I have called the ‘non-relation view’. On the non-relational view consciousness consists in having the relevant higher-order state. There is some discussion of this distinction in Pete Mandik’s chapter at the end of the book (under heading of ‘cognitive approaches to phenomenal consciousness’) but if one just read Gennaro’s chapter on higher-order theory one would be misled about the other approach.

This comes out clearly in Gennaro’s discussion of the ‘mismatch’ objection. A familiar objection to higher-order theories is that they allow the possibility of differing contents in higher-order and lower-order states. If one sees a red object but has a higher-order thought of the right kind that represents that one as seeing a green object, what is it like for the subject? The non-relational view answers that it is like seeing green even though one will behave as though one is seeing red. Gennaro disagrees and says that there must be a partial or complete match between the concepts in the HOT and the first-order state (or the concepts in the higher-order state must be more fine-grained than in the lower-order state or vice versa) or there is no conscious experience at all. He considers cases like associative agnosia, where someone can see a whistle and consciously see the silver color of it and its shape, can draw it really well, etc, but doesn’t know that it is a whistle. They just can’t identify what it is based on how it looks (though they can identify a whistle by its sound). Gennaro holds that the right way to interpret this is that the subject has a higher-order thought that represents the first-order representation of the whistle incompletely. It represents that one is seeing a silver object that has such and such a shape. But it does not represent that one is seeing a whistle (p 156). He argues that in a case of associative agnosia there is a partial match between the HO and FO state and that results in a conscious experience that lacks meaning.

First it is strange to be talking in terms of ‘matching’ between contents. What determines whether there is a match? Gennaro talks of the ‘faculty of the understanding,’ and it ‘operating on the data of the sensibility’ by ‘applying higher-order thoughts’, and of the higher-order state ‘registering’ the content of the first-order state but it is not clear what these things really mean. Second he makes the assumption that one consciously experiences the whistle as a whistle, or that high level concepts figure in the phenomenology of a subject. This is a controversial claim and even if it is true (or one thinks that it is) one should recognize that this is not a required part of the higher-order view. On the way Rosenthal has set the theory up one has higher-order thought of the appropriate kind about sensory qualities and their relations to each other but one does not have concepts like ‘whistle’ in the consciousness-making higher-order thoughts. One will then come to judge/make an inference that one is seeing a whistle which will result in a belief that one is seeing that whistle, but this belief will be a first-order belief (that is, a belief which is not about something mental, in this case it is about the whistle).

Gennaro says that these kinds of cases e support the claim that there must be some kind of match between first-order and higher-order states but it is not clear that it really does. What he has argued for is the claim that the content of the higher-order state determines what it is like for the subject. What reason do we have to think that the match between first-order and higher-order state is playing a role? In other words, what reason do we have to think that the same would not be case when the first-order state represented red and the higher-order state that one was seeing green, as the non-relational view holds?

His sole criticism of the non-relational view comes when he says,

but the problem with this view is that somehow the [higher-order thought] alone is what matters. Doesn’t this defeat the purpose of [higher-order thought] theory which is supposed to explain state consciousness in terms of a relation between two states? Moreover, according to the theory the [lower-order] state is supposed to be conscious when one has an unconscious HOT,” (p 155; italics in the original).

This is a really bad objection to the non-relational version of the higher-order thought theory. The first part merely asserts that there is no non-relational version of the higher-order thought theory. The second part is something that Rosenthal accepts. The lower-order state is conscious when one has an appropriate higher-order state because that is what that property consists in. What it is for a first-order state to have the property of being conscious, for Rosenthal, is for one to have an appropriate higher-order thought which attributes that first-order state to .

In addition, Gennaro goes on to criticize the recent speculation by higher-order theorists that the prefrontal cortex is crucially involved in producing conscious experience. It is of course an open empirical question as to whether the prefrontal cortex is required for conscious experience and, if so, whether it is because it instantiates the relevant kind of higher-order awareness. However, Gennaro’s arguments are extremely weak and do nothing to cast doubt on this empirical hypothesis. He first appeals to work by Rafi Malach that there is decreased PFC activity when subjects are absorbed by watching a film. However, he does not note that Rosenthal and Lau responded to this. He then appeals to the fact that PFC activation is seen only when there is a required report. This has also been recently addressed (by Lau). Finally, he appeals to lesion studies suggesting that there is no change in conscious experience when the PFC is lesioned. However, there is considerable controversy over the correct interpretation of these results and Gennaro merely appeals to second and third hand literature reviews (see the recent debate in the Journal of Neuroscience between Lau and colleagues and Koch and colleagues).