Two for one

30 December 2004

Buy one, get one free

Over Christmas, I was looking at an interesting old book - 'The Mechanic's Pocket Dictionary', by William Grier. This was the eighth edition, published in Glasgow in 1846. A surprising amount of the book is still an interesting read; the really striking thing is what it reveals about the scientific outlook of the average engineer as late as 1846.

For one thing, Grier starts with an introduction which carefully explains the meanings of the common mathematical symbols '=', '+', '-' and so on. 'Many who are not acquainted with the use of these signs' he explains, 'are led to believe, that they are employed merely as a parade of mathematical learning, which only serves to make the subject more intricate; but this is a mistake...'  It seems extraordinary now that the average engineer of 1846, someone interested in constucting marine steam engines and other high-tech Victorian equipment, might have regarded basic arithmetical symbols as a pretentious affectation.

Equally surprising is the fact that, according to Grier, some at the time believed that evaporation was due to a chemical reaction between water and air - though Grier himself dismisses the idea. How could mid-nineteenth century engineers have been so confused about the nature of evaporation? Well, one reason may be that, again according to Grier, they had not properly grasped the distinction between heat and temperature, or the precise nature of either.

'It is matter of dispute among philosophers whether the cause of the phenomena of heat be a subtile fluid, capable of penetrating all substances, or a peculiar vibration, rotation, or other kind of motion'  he says. It is remarkable that the theory of caloric fluid was apparently still a respectable contender at the time, and scarcely less surprising that engineers then regarded the nature of heat as a matter best left to the philosophers. Grier goes on to describe with great clarity the experiments which show that heat can be reflected and focused by mirrors, a phenomenon, he says, known as 'radiation', and it is hard to believe he had much time for caloric fluid himself.

The case of heat and temperature provides an interesting example of a scientific problem whose chief difficulty lay in drawing a conceptual distinction between two related phenomena which had previously been regarded as the same thing. Personally I can sympathise more readily with the mid-Victorian engineers when I remember my own continuing confusion over the nature of light, where we seem to have a comparable but opposite difficulty  - waves or particles? Well, sort of both at the same time, really, whatever that means...

It has, of course, been argued that many of our problems in grasping the nature of consciousness stem from our tendency to treat it as a single phenomenon, when in fact the word refers to two or more quite different things. Perhaps the clearest and most outspoken advocate of this point of view is Ned Block, who refers to consciousness as a 'mongrel' concept, and draws a distinction between access consciousness and phenomenal consciousness.

Block's way of dividing up consciousness is useful because it captures clearly the distinction which people frequently make; between subjective, qualia-laden experience on the one hand, and relatively comprehensible, computational decision-making processes. This is pretty much the same distinction as the one drawn by Chalmers between the 'hard' and 'easy' problems, for example. Most people, I think, would accept that it is a distinction worth making, though some would add other divisions, or incorporate Block's point in a more complex hierarchical structure.

But in another way, the distinction is not helpful at all. When we draw a distinction like this, we want it to dispel at least some of the mystery around the topic. Block's approach seems, instead, to leave phenomenal consciousness as mysterious as ever. This is OK if, like Dennett , you want to go on to denounce qualia in all their forms as delusions, but not so good if you want to find ways of naturalising them, as I think most of us do. Moreover, even the 'easy' side of the split is left more mysterious than first appears. Our problem-solving, decision making thoughts may be computational, but they certainly need to be about things, and the mystery of aboutness, or intentionality, is arguably as intractable as that of qualia. It gets slightly less attention mainly because it is, as it were, better camouflaged. All our thoughts are so saturated with intentionality we find it easy to overlook.

A completely different tactic here is to try to make one mystery explain the other. Thus Searle , if I have understood properly, would like to see the roots of intentionality in qualia: the qualia of hungriness is inherently about food, and it is from such inherent aboutness that all the other meanings and aboutnesses derive. If this is broadly the right line to be pursuing, then Block's distinction pulls apart the very things we need to bring together.

I'm not absolutely sure that the Searlian strategy is the right one. The general idea of trying to redefine the issues along completely new lines seems appealing however. From some angles the problem of consciousness looks daunting, but it sometimes seems that if only we could realise that we are confusing x with the completely separate matter of y, or that we need to consider n as really just another facet of p, the whole thing might suddenly make a new kind of sense. Perhaps we do need a cognitive Einstein who can point out that the mental equivalents of space and time are not really separable after all, but different facets of the underlying reality, interval, or provide some other equally fundamental change of perspective. Then, in 150 years or so, people will find it hard to believe we were still confused about all this...

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