Is The Higher-order Approach To Consciousness Plausible?

This article will maintain that the higher-order approach is the most plausible way to explain the phenomenon of consciousness. I will appeal to two entirely different versions of higher-order theories - Nobel Prize-winning neuroscientist Gerald Edelman`s account of consciousness and the philosopher David Rosenthal`s actualist higher-order thought (HOT) theory - and explain why their accounts are plausible. Dispositionalist HOT theories, like those advocated by Carruthers, will not be discussed. This article will focus on resolving an objection to higher-order theories put forward by David Chalmers and assess to what extent, if any, this objection undermines the credibility of Edelman and Rosenthal`s position.

First, I outline Rosenthal`s HOT theory in its basic form. Chalmers summarises the basic tenet as follows: "a mental state M is phenomenally conscious if and only if a subject has a higher-order thought about M...a higher-order thought about M should be understood as a thought by the subject with the content "I am in M"." In other words, Rosenthal argues that a first-order mental state is conscious if we are aware of ourselves as being in that state, and such an awareness is caused by having a thought that we are in that state. These higher-order thoughts are seldom conscious themselves, though they make first-order states conscious when they direct themselves at them. Unconscious states, therefore, are those that don`t have higher-order thoughts directed at them. For example, consider that I have a first-order mental state about a blue car. This state remains unconscious until I have a thought directed at it, such as: "I am seeing a blue car", or, "there is a blue car parked in the street". Henceforth this mental state becomes phenomenally conscious.

Rosenthal`s theory has its strengths. I believe that the account of consciousness he gives is quite intuitive at face value. It appears to be largely in tune with our attitudes towards consciousness, in our belief that we become conscious of something when we turn our thoughts to it, and also in our view that most of our perceptual experience remains unconscious. Indeed, we do not consider ourselves to be conscious of every detail in our field of vision at every moment in time, unless we explicitly introspect upon a particular visual experience. Moreover, the HOT theory gives us a definitive method of distinguishing between conscious and unconscious mental states: conscious states are those mental states which are the object of a higher-order thought about them. The ability to easily make such distinctions is certainly a benefit of adopting the HOT approach. However, the theory faces a strong objection from Chalmers which threatens to compromise its credibility.

Chalmers` criticism is that HOT theories are incompatible with the more plausible and convincing `unity thesis`, and as such he finds grounds for rejecting all HOT theories as false. He states the unity thesis thus: "necessarily, any set of conscious states of a subject at a time is unified." he argues for this on the grounds that "it is difficult or impossible to imagine a subject having to phenomenal states simultaneously, without there being a conjoint phenomenology for both states." For example, if I am holding a red book, then I am experiencing multiple phenomenal mental states - the visual character of the colour red as well as the tactile sense of the book`s size and weight - but each state does not present itself to me separately, they are experienced as a complete unified scene which has a `conjoint phenomenology`. The idea of unified consciousness seems incredibly intuitive, possibly more so than Rosenthal`s HOT theory, and the unity thesis is difficult to refute entirely. Thus HOT theories face a major problem if they are shown to be incompatible with the unity thesis. I now explain why Chalmers considers the two to be conflicting, and then assess the success of his objection in undermining the plausibility of HOT theories.

The main line of his objection is that HOT theories are incompatible with the unity thesis because the HOT account of consciousness gives "not reason to believe that phenomenal states or phenomenally conscious mental states will always be unified." This needs some further explanation for clarity. The unity thesis states that if we have a number of phenomenally conscious mental states, then their conjunction is a phenomenally conscious mental states, and the reason this is problematic for HOT theories is because it commits them to claiming that if we have mental states A and B, and the thoughts `I am in A` and `I am in B`, then we necessarily have the thought that `I am in A&B`, which seems wrong. Chalmers uses, as an example demonstrate this, the case of a person with contradictory beliefs. This person knows they have each belief, but never puts the two together. They might have the thought `I believe p` and `I believe not p`, without ever expressing both in the thought `I believe p and not p`. Thus, there is not necessarily (or even typically, Chalmers asserts) any conjunctive unity with higher-order thoughts in the way that the unity thesis proposes about conscious mental states, and therein lies the problem. If we accept the unity thesis, then we must deny any HOT theory, since we cannot typically find such conjunctive unity in higher-order thoughts about first order mental states. This is a very worrying position for the HOT theorist to find themselves in. They are stuck between a rock and a hard place, as it seems they must either reject the convincing unity thesis, or else abandon some fundamental features of their own theory.

Chalmers himself cites several possible responses that a HOT theorist could make to his objection. The most obvious, he observes, would be simply to deny the truth of the unity thesis. This is in fact a tenable response, since the truth of the unity thesis is not known unequivocally, however to deny it would be to go against very strong intuition. Thus, I cannot see that rejecting it would readily suffice as a response. Moreover, if a HOT theorist was to reject the thesis, then the onus would be on them to give an account of why they considered it to be so fundamentally wrong - an extremely difficult and philosophically demanding task.

The second response that Chalmers notes is the possibility of embracing a more limited version of the unity thesis. It is this line that Rosenthal takes, to try to rescue his theory, by claiming that all we have is a `sense` of the unity of consciousness. This sense, he argues, comes about because each higher-order thought represents a first-order mental state as belonging to the person who thinks the higher-order thought. In other words, the unity that binds all our higher-order thoughts is a sort of unity of subjectivity: all our higher-order thoughts seem to be unified in their belonging to us. And thus consciousness appears to us to be unified, due to the subjectivity of higher-order thoughts. It is this subjective unity which Rosenthal argues is present in our consciousness.

I argue that Rosenthal`s response is a good one. I believe the idea of subjective unity to be even more plausible than the unity thesis itself. Indeed, the complex mechanisms of the mind give us no reason to believe that a unity of consciousness occurs in actuality - this is just how our consciousness appears to us. Therefore, a kind of subjective unity, from which we gain this sense that consciousness is unified, is actually much more believable. Rosenthal has taken a limited version of the unity thesis, and shown it to be both plausible and in accordance with his own HOT theory, and as a result he has avoided Chalmers` objection successfully.

On a different note, I thought it would be interesting to briefly discuss a more scientific higher-order theory of consciousness, namely Gerald Edelman`s. Edelman first makes a distinction between primary consciousness and higher-order consciousness. Using a Darwinian evolutionary model, he builds his theory from the bottom-up, starting with primary consciousness, which he defines as "the state of being mentally aware of things in the world, of having mental images in the present...it is not accompanied by any sense of a socially defined self with a concept of a past or a future." This primary consciousness is the ability to create scenes and to make discriminations, which Edelman calls the "remembered present". It denotes the varieties of perceptual awareness that we share with certain animals whose brain organisation is similar to our own. Edelman builds upon his theory of primary consciousness to provide for what he calls higher-order consciousness. Through the evolution of an additional reentrant capability (I will not expound the specific scientific details Edelman gives, as this lies beyond the scope of the article), primary consciousness can give rise to higher-order consciousness, which he defines as the "ability to be conscious of being conscious...it allows the recognition by a thinking subject of his or her own acts and affections." The capacity for higher-order consciousness is present in animals with semantic or linguistic abilities - those with full linguistic abilities (namely humans) are able to have a social concept of the self as well as a concept of a past and future. The higher-order consciousness that emerges still depends on primary consciousness (similar in a way to Rosenthal`s theory), which is necessary for higher-order consciousness to operate.

Whilst a proper analysis of Edelman`s scientific explanation for higher-order consciousness is beyond the scope of this article, I feel that we can, at the very least, agree that his account is wholly plausible. Indeed, he has used all the tools available in cutting-edge neuroscience to formulate his higher-order approach, so if we were to contend that his theory isn`t plausible, then we would do extremely well to find any theory of consciousness around today that is! furthermore, Chalmers` unity thesis objection doesn`t really apply, since Edelman`s theory isn`t grounded specifically in higher-order thoughts. In fact, he fully accepts the idea of unity, maintaining that consciousness is a "unitary or integrated" phenomenon.

The main limitation of Edelman`s account of consciousness is that he does not try to give a full explanation of qualia. He claims only that "differences in qualia are based on differences in the wiring and activity of parts of the nervous system...qualia are always experienced as parts of the unitary conscious scene." In fact, he holds that a true explanation of qualia lies beyond the scope of theoretical science: "given that only a being with an individual body and brain can experience qualia, this kind of descri ption [theoretical] is not possible." His position draws parallels with new mysterianism (a stance advocated by McGinn), which claims that humans will never be able to properly solve the hard problem of consciousness since the human mind is incapable of comprehending itself entirely. I do not think that Edelman`s reluctance to account for qualia is something that significantly undermines the plausibility of his theory, since I agree with him and McGinn in the belief that we will never be able to properly account for qualia to properly explain the explanatory gap and solve the hard problem.

From analysing Rosenthal and Edelman`s higher-order theories, I can conclude fairly effusively that the higher-order approach to consciousness is plausible. Moreover, I am inclined to believe that it is the most plausible account of consciousness we have so far. Edelman`s higher-order account gives an in-depth neuroscientific and biological explanation of higher-order consciousness and its relation to primary (or first-order) consciousness. Even Rosenthal`s philosophical theory is in line with a lot of modern psychology, and he successfully avoids a potentially fatal problem regarding the incompatibility of HOT theories with Chalmers` unity thesis.

References:

Chalmers, David. 2010. The Character of Consciousness (O.U.P.). Edelman, Gerald. 2004. Wider than the Sky: the Phenomenal Gift of Consciousness (Yale University Press). Rosenthal, David. 2011. Exaggerated Reports: reply to Block (O.U.P.).