Month: September 2014

The science of consciousness, “why” questions, and philosopher David Chalmers (Part 1)


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 (, 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 ( – 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 (

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).

Are sunsets “real”? Reducing reductionism


(Sunset over Yellow Waters Billabong, NT, Australia)

Before embarking upon what will be a discussion of the semantics of reductionism, I suppose I had better define one of the “basic” words in the title of this article: “real”. So, for the benefit of any philosophers or semanticians that might be reading: “real”, in the title and elsewhere in the article, should be taken to mean “actual” (a discussion of the “categories of the real” might be the topic of a later post).

Now that we’ve got that nonsense over with, why am I questioning the reality of sunsets anyway? The inspiration for this post is John Searle’s discussion of reductionism in his book Mind: a brief introduction, in which he elucidates the ways in which the phenomenon of consciousness can and can’t be reduced.

There are many types of reductionism (reductionism itself is reducible): theoretical, methodological (two types), conceptual, causal, ontological, eliminative, etc. Searle focuses his discussion on the latter three types – causal, ontological and eliminative. The definitions are as follows:

Causal reduction: reducing a phenomenon to its causes. An example (one used by Searle and Dennett and others, following Eddington) is the “solidity” of objects, which is caused by “a certain sort of molecular behaviour” (Searle’s words), such that we perceive them to be solid despite the fact that they are largely composed of empty space.

Ontological reduction: an item’s ontology is basically what it “is” (what it can be said to be), thus, when we causally reduce solidity to the behaviour of “molecules” (more properly the behaviour of electrons), we also ontologically reduce it – solidity “just is” the behaviour of electrons (i.e. it is nothing “beyond” this).

Eliminative reduction: this is really a subtype of reduction whereby we eliminate something by reducing it causally and/or ontologically. It is often believed that all (or most) reduction is eliminative, but this is certainly not the case. For example, although we causally and ontologically reduce solidity, we do not thereby eliminate it. This is easy enough to discover by conducting the simple experiment of running headlong at an apparently solid wall. Despite the fact that we can causally and ontologically reduce solidity to the behaviour of electrons, thereby showing that the wall is mostly composed of empty space, the aforementioned experiment is still likely to result in some unpleasant bruises. An example of a phenomenon on that can be eliminated through reduction might be ghosts – when we causally and ontologically reduce the perception of ghosts to an illusion caused by apophenia (seeing patterns where there are no patterns) or sleep paralysis, we also eliminate the existence of the ghosts themselves.

Searle utilises these definitions to argue that consciousness is causally reducible (to the “firing of neurons”), but not ontologically reducible (i.e. it is something “beyond” the firing of neurons – it is our experience of subjectivity). So far so good*. Where Searle goes wrong is in his choice of examples: he uses the aforementioned example of solidity as something that is ontologically but not eliminatively reducible; then uses sunsets as an example of a phenomenon which is eliminated through reduction.

To determine whether or not this example is apt, we need to question what is actually meant by “sunset”. Searle’s comment that “the sun appears to set over Mount Tamalpais though it does not really do so” is instructive. It suggests that Searle thinks that within the meaning of the word “sunset” is the literal assertion that the sun is spatially proximal to the edge of the world behind which it appears to disappear. I contend that this is not the case….at least since Copernicus.

This discussion has parallels with Eddington’s “paradox of the two tables”, to which Searle makes indirect reference in his discussion. According to Eddington, when we look at a table we are in fact seeing two different tables. One, the table of the “scientific image”, is mostly composed of empty space, appearing solid because of the activity of electrons in the atoms from which it is constructed. The other, the table of the “manifest image”, is “merely” solid, constructed from solid pieces of wood and not composed of (rather surrounded by) empty space at all. Of course there is only one table, with two perspectives from which to consider it. Viewed from either perspective, the table is solid (i.e. the solidity of the table is not eliminatively reducible).

So what about sunsets? Since Copernicus, we have known that the sunset is a matter of perspective, caused by the rotation of the Earth on its axis. So, the sunset is causally reducible – this is our “scientific image” of the sunset. Our “manifest image” of the sunset contains things like the warm orange and red glow suffusing the evening sky and the sun itself slowly slipping from view behind whatever feature of the horizon is situated to the west of us at the time; it is the gradual change from day to night. So, does our causal reduction of the sunset (for the purposes of the present discussion let’s forget whether what we mean by “sunset” is ontologically reducible) eliminate the phenomenon in the same way that our causal reduction of ghost sightings to apophenia might do? Of course not. The sunset is a real (actual) phenomenon. Lovers standing hand-in-hand both see it, voyeurs watching the lovers see it, the voyeurs’ cameras see it; it is objectively real. The fact that it is causally reducible to the Earth’s rotation does not make it eliminatively reducible: one may as well say that the day-night cycle is eliminatively reducible, because it has the same cause.

Bad example, Searle, bad!

The accusation could be made that, although I’ve hinted at it, I’m yet to actually provide a proper definition of the sunset myself. Well, here goes – the “sunset” is that thing that happens at dusk just before day becomes night, often characterised (cloud cover permitting) by the sky changing colour and the sun disappearing from view. It is a “matter of perspective”, and varies spatio-temporally according to longitude and latitude. The word “sunset” contains no astronomical information, i.e. it does not have a position on whether the sun literally “disappears” (actually this is what it literally does, just not in the “magical” sense) or literally goes behind certain features of the westernmost horizon (and then teleports to a position behind certain features of the easternmost horizon just before dawn). Most of us are well aware that it’s the Earth’s rotation on its axis that causes this phenomenon, just as the same rotation causes the phenomena of night and day. The sunset is a manifest, objectively real, romantic, actual phenomenon that cannot be eliminated through reductionism. Good enough?

Why did I write this article dissecting the semantic arguments of an eminent philosopher? Firstly, because it was fun! Secondly, because I think it highlights a core issue in the way Searle (along with many other “thinkers”, both philosophers and scientists) structures arguments: by deriving the arguments from the conclusions and not the conclusions from the arguments. For other classic examples of this see Searle’s “Chinese Room” thought experiment, or his claim that he is neither a “property dualist” or a “materialist” (I think the claim can be made that he is both) – it often seems to be the case with Searle that the position he is attacking (e.g., some sort of literalist interpretation of “sunsets” or his particular definitions of property dualism and materialism) exists nowhere other than in his polemic itself. This sort of “intentional definitional error” – the creation of a fictitious position in order to take it down – is known as a “straw man argument”. Perhaps it’s inconsequential with regard to “sunsets” (although it muddies the waters of his otherwise clear discussion of reductionism), but his application of it here is symptomatic of the widespread usage of the tactic elsewhere in his writings on consciousness (a tactic that has generated considerable head scratching amongst other thinkers on the subject).

P.S. Searle lovers – let it be known that I understand and agree with his assertions regarding the reducibility and non-reducibility of consciousness. That is not the point of this article.


*Except where he tries to use this line of reasoning to attack both “property dualism” and “materialism”.