Consciousness is something we are all intimately familiar with – we not only possess it, we inhabit it. Unfortunately, deep familiarity and deep understanding do not always go hand in hand and the vast majority of us know very little about consciousness – how it arises, how it evolved or what its function is. Indeed even at the cutting edge of science many questions about consciousness remain unanswered. The study of consciousness is one of those branches of science (theoretical physics is another), increasingly rare in the 21st-century1, in which philosophical and experimental science stand side-by-side on almost equal footing. Attend a conference of the Association for the Scientific Study of Consciousness (ASSC), as I did earlier this year, and you will find the papers almost evenly divided between the philosophical and theoretical or experimental approaches.
Not only are many questions about consciousness yet to be answered, many scientists and philosophers are unable to agree as to the very nature of the questions themselves. One particularly contentious question is the so-called “hard problem” of consciousness research. The hard problem, as elucidated by philosopher David Chalmers (https://www.youtube.com/watch?v=uhRhtFFhNzQ), the man who coined the term, is the “why?” of consciousness – why do certain types of brain activity give rise to the experience of subjectivity? Chalmers says that identifying the brain activity associated with the various subsets of conscious experience constitutes the “easy problem(s)”. He maintains that even when “neural correlates” for all conscious experiences have been identified the hard problem will remain unsolved.
A founding member of the ASSC, Chalmers believes that the hard problem is a scientific question for which a scientific answer is possible. In his 1994 paper “Facing Up to the Problem of Consciousness”, he states that pessimism regarding the possibility of a scientific theory that explains consciousness is premature despite the fact that reductionist explanations of consciousness have, in his view, failed. Chalmers believes that a non-reductionist explanation is required and therefore that the hard problem may be answerable via panpsychism (http://en.wikipedia.org/wiki/Panpsychism) – by treating subjectivity as a fundamental property of matter, rather than something that arises secondarily through functional evolutionary pathways. Essentially, Chalmers is suggesting that what is generally considered a question for biology (in which there are both properties and functions) should be treated as a question for physics (in which there are only properties). Although this seems like a category error, in itself it is not an intrinsically “unscientific” approach. However, leaving aside his claim that reductionist theories of consciousness have failed to account for subjectivity, let’s consider whether or not the hard problem is indeed a scientific question.
I propose that we can divide why? questions roughly into two discrete categories: “mechanistic why?” and “metaphysical why?”. An example of a mechanistic why? is the kind of question evolutionary biologists routinely investigate, e.g., “why is the venom of some Australian snakes so toxic to lab mice?” Such a mechanistic why? can be further divided into two subcategories – it is either a question about property or a question about function. The philosopher Daniel Dennett has referred to these as “how come?” (property) and “what for?” (function) questions. Rephrased, we can derive either “what are the specific biochemical properties of the venom that make it so toxic?” (property); or “what are the evolutionary selection pressures that have resulted in the venom being so toxic to lab mice?” (function), from this one mechanistic why? A mechanistic why? is therefore a question that can be easily and effectively rephrased as one or other of the two kinds of what? A metaphysical why?, on the other hand, concerns the “ultimate reason” for things being as they are. A classic metaphysical why?, derived from the Anthropic Principle, is: “why are the physics of our universe such that on this planet the conditions are precisely right for life to arise and humans to eventually evolve?” Questions such as these have been amusingly termed “vertiginous questions” by Scott Aaronson (http://www.scottaaronson.com/blog/?p=1799).
Science is not fond of metaphysical why? because they do not function as standard hypotheses – they generate no predictions and are thus fundamentally untestable. Although there is no universally accepted definition of the scientific method, it is often considered that a major pathway2 through which science advances is the generation of testable hypotheses. Scientific hypotheses generate predictions about observable reality in the format “if A (the hypothesis) is true, then B will be observable.” It is not strictly speaking necessary that a hypothesis be immediately testable with current technology, but it must generate predictions that are testable “in theory”. Questions about “ultimate reasons” generate no predictions.
Like experimental science, the field of metaphysics concerns itself with what? and largely eschews why? Here is a modern definition of metaphysics (emphasis mine):
“Metaphysics is about what could be and what must be. Except incidentally, metaphysics is not about explanatorily ultimate aspects of reality that are actual.” (Conee and Snyder, 2005)
So, a metaphysical what? asks “what is actual or possible?”; whilst a metaphysical why? question asks “why are things actual or possible?” An example of the former is “are there atoms?” An example of the latter is “why are there atoms?” If science eschews metaphysical why? because they are fundamentally untestable, why should metaphysics eschew them? After all, metaphysics is concerned with the possible as well as the actual and the testability or predictive power of metaphysical questions is not relevant. One reason may be that answers to metaphysical why? only beget more metaphysical why? – to ask a metaphysical why? is to set in motion a never-ending chain of questions that beget questions that beget questions. Perhaps another reason is that answering a metaphysical why? (i.e. postulating an “ultimate reason” ) would seem to require the existence of what Daniel Dennett has termed an “invisible intentional system”. There is a major branch of philosophy that concerns itself with the asking of metaphysical why? – theology.
So what about the hard problem of consciousness? We’ve established that it’s a why? – but what sort of why? Let’s begin by examining the question in more detail, first as it was posed in Chalmers’ 1994 paper “Facing Up to the Problem of Consciousness”, and then in his more recent elucidation of it in the previously linked TED talk. In the 1994 paper, Chalmers initially defines the hard problem in the following passage (emphasis mine):
“Why is it that when our cognitive systems engage in visual and auditory information-processing, we have visual or auditory experience: the quality of deep blue, the sensation of middle C? How can we explain why there is something it is like to entertain a mental image, or to experience an emotion? It is widely agreed that experience arises from a physical basis, but we have no good explanation of why and how it so arises. Why should physical processing give rise to a rich inner life at all? It seems objectively unreasonable that it should, and yet it does.”
Although it contains the word “why” four times, there’s nothing in this passage that makes it explicitly clear what kind of why? Chalmers is asking – taken out of context, he could be asking a question about the mechanisms from which subjectivity arises or about the selection pressures that have favoured the evolution of subjectivity. As we’ve seen, however, Chalmers defines the hard problem in relation to the easy problems. In the same paper, he tells us that the “…easy problems of consciousness include those of explaining the following phenomena:
- the ability to discriminate, categorize, and react to environmental stimuli;
- the integration of information by a cognitive system;
- the reportability of mental states;
- the ability of a system to access its own internal states;
- the focus of attention;
- the deliberate control of behavior;
- the difference between wakefulness and sleep.”
In the TED talk, he tells us explicitly that identifying the neural correlates of consciousness will not answer the hard problem. During the talk, he phrases his why? in the following way:
“We know that these brain areas go along with certain kinds of conscious experience, but we don’t know why they do.”
And tells us that the “real mystery” is “why is it that all that physical processing in the brain should be accompanied by consciousness at all?”
Chalmers thereby makes it clear that one avenue of interpreting the hard problem as a mechanistic why question is closed to us – he explicitly tells us that the mystery is not what kinds of brain activity subjectivity arises from, but why it arises from this brain activity. So, despite his desire to frame the hard problem as a question for physics, for Chalmers the “hard question” is not a “how come?” (property) question about the brain. Nor, apparently, is it a “what for?” (function) question – at no point in his discussion, in either the paper from 1994 or his TED talk, does Chalmers mention evolution. In fact, he tells us that unlike Daniel Dennett he finds a functional explanation of consciousness to be unsatisfactory. It is therefore clear that his why? can not be interpreted in terms of selection pressures favouring the evolution of subjectivity.
It seems we can be reasonably confident in ruling out the hard problem as a mechanistic why? altogether. Chalmers says that he is “a scientific materialist at heart” and that the panpsychist approach he advocates “opens up the way to do science” with consciousness, but then he explicitly disavows both possible scientific interpretations of his why?, including the one “opened up” by reframing it as a question for physics (i.e. a question about properties). It appears Chalmers’ hard problem is a metaphysical why? – a search for the “ultimate reason” that subjectivity exists.
In Part 2 of this article, I’ll be considering why (ha!) we feel so compelled to ask why?
1 A compelling case can be made for the point that the generalised “separation” of science and philosophy (including philosophy of science) is to the detriment of scientific thought.
2 There are others, but they are less relevant to the asking of specific questions (i.e., the generation of hypotheses).