Archive for June, 2006

Push SinghI was shocked this week to discover, browsing through my list of pages to revisit when time allows, that Push Singh died a few months ago. He was universally regarded as a young man of exceptional promise, and poignantly his page still records that he was to join the MIT Media Lab faculty in 2007.

He certainly had some original ideas. A presentation he gave on the Future of the Mind envisages, among other things, that we might all carry around with us small electronic replicas of our own minds and personalities, able to interface with other people’s replicas and with other sources of data, helping to identify and arrange things which deserve to be brought to our attention. A rather nerdy dream, this one: our cybernetic duplicate manages all the messy and tiresome details of human interaction, and we get to meet the few interesting people, see the occasional worthwhile film, and so on, without having to sacrifice valuable lab time on small talk and merely social activity. We might also, he suggests, be able to improve ourselves by consulting the duplicates of our heroes and exemplars (some care would be required, I think).

The same talk floats the curious idea that in the new world of the future, we may need new emotions. I find it difficult even to come at this idea in any effective way from a philosophical, and particularly from a phenomenal perspective: it seems to require an underlying metaphysics of the emotions which does not exist and is not easily conceived of. It’s a bit easier, and probably more appropriate here, to think of the emotions in more practical terms, as predispositions to act in certain complex ways (a valid point of view even for those who don’t think that is all emotions amount to). Perhaps the feeling you have when you find that someone has been consulting your electronic model of yourself will deserve a new name – rather like the feeling, never experienced before the late twentieth century, caused by discovering that your mother has been reading your blog. It seems unlikely to me that the basic underlying vocabulary of the emotions could ever change, but it might be that the territorial instincts that lie at the bottom of many emotions might need to undergo some change in a world of virtual property and instant global interconnection.

But Push was chiefly concerned with common sense, and the difficult task of endowing machines with it. This problem, in many different guises, may well be the central challenge of AI research, and for that matter, of consciousness itself. Computers deal well with problems which can be defined in advance, where the range of objects and contingencies which need to be considered is known and limited. In real life, problems are never like that: their solution by human beings usually depend on two special human resources: first, a vast and heterogeneous fund of background knowledge and assumptions, and second a remarkable capacity for picking out relevant factors (or it might be more accurate to say a masterly ability to ignore millions of irrelevant ones).

Push was a disciple of Marvin Minsky (and indeed it was through his comment on a piece of mine about Minsky that he got onto my reading list), and the approach to the problem he followed is represented by the Open Mind Common Sense project. The philosophy behind this work is essentially that if common sense requires a vast set of pieces of knowledge, the sooner we start collecting them the better. There are various places from which to harvest miscellaneous information: in principle you could simply empty the contents of encyclopaedias and other books into your database, or vacuum up the contents of the internet (if we can properly see the internet as a repository of common sense). The strategy adopted here was to allow human beings to feed in facts one at a time through a specially designed web site. The project’s outlook and strategy is quite similar to that of the long-running CYC project.

Although you can’t help admiring the spirit of these vast projects, my honest view is that they are founded on a misconception. If we represent common sense as a series of propositions, the list of those propositions is indeed a vast one. It may well be infinite. I know, for example, that I shouldn’t drive after more than two drinks. I also know I shouldn’t drive after more than three drinks, and so on for any given number of drinks. You may think that most of the members of this unending series of propositions are blindingly obvious, but it’s pretty much this kind of obviousness that we need our machines to recognise and deal with. If we do it by writing lists, the job will go on forever. The truth, I think, is that common sense does not consist of a list of propositions at all.

That doesn’t mean the work being done on these projects is wasted. They may never replicate human common sense, but they might well lead to interesting new artificial forms of it. It’s certainly true that the approaches taken have become more sophisticated over the years, and it might well be that the understanding this work helps generate – of how to deploy a collection of diverse, specialised databases and scripts to cope with different areas of reality – might eventually become so valuable that the size of your common sense module’s database of facts seems a secondary consideration.

Certainly there are some indications in Push’s thesis of interesting departures. In his scenario of Green and Pink, two one-armed robots, Green seeks Pink’s help in constructing a table. Confused, Pink starts to pull off one of the table legs, but by attaching one himself, Green demonstrates his intention and fruitful collaboration ensues. At first sight this looks rather like the simple block worlds which have been a staple of AI research for so long: but if we take a closer look the communication going on seems to feature Gricean natural meaning, or (stretching it a bit) something like implicature. These, in human communication, are exactly the kind of tools we use to understand messages that are not spelled out in the explicit words, and pick up implications that are not, so to speak, already coded in. If a faculty for those could be successfully incorporated into a functioning AI module, we should take a very major leap forward.

Tragically, we’ll never know what Push Singh might have contributed.

HeadColin McGinn is well-known as a leading champion of ‘Mysterianism’ – the view that consciousness is ultimately beyond our capacity to understand. On his version, human beings suffer from ‘cognitive closure’ in respect of consciousness: although there is really nothing unnatural or magic about the connection between consciousness and physics, our mental processes are just not up to the job of explaining it.

Besides this main case, McGinn has also offered another argument which buttresses his position, about the spatial, or rather the non-spatial nature of consciousness. In a nutshell, he suggests that while all physical events have both a time and a place, conscious events have only a time. It’s hard for us to understand how this could be the case at all, let alone how, if it were truly the case, mental and physical events could be intimately related. Yet to preserve a monist account of the world, we need to suppose that mental events actually arise out of physical ones, or the other way round. McGinn, of course, does not really need to attempt to construct a way out of the impasse – he merely has to suggest that, as a matter of fact, it’s incomprehensible to us.

There are some hints in the paper about what kind of theory of consciousness McGinn might be tempted to endorse if he didn’t think theories of consciousness were beyond us. It’s hard to see how mental stuff can have emerged from the non-mental world, he says: there’s a kind of analogy with the Big Bang, wherein space emerged from non-space. It seems absurd to McGinn to suppose that the Big Bang was actually the beginning of time itself (in a footnote he rebukes those who have suggested this, for drawing a metaphysical conclusion from an epistemic premise, ie arguing that things we can’t know about, such as times before the Big Bang, therefore don’t exist); as a heady speculation, we might be tempted to guess that that same unknown stuff which supports our mental life also preceded and supported the emergence of the physical world. In his heart of hearts, it seems McGinn might like to believe that this esoteric ur-mental stuff of which we know nothing is, in ways we don’t understand, the ultimate substrate of reality. However that may be, it seems to McGinn that some sort of unknown stuff is out there somehow: neither dualism nor monism can really be made to work, and most likely it is because our understanding of the physical world is missing out something big and important: ‘The brain must have aspects that are not represented in our current physical world-view.’ Aspects, as it happens, that that same brain is incapable of grasping.

I find the initial claim that consciousness is located in time but not space, appealing enough. It is intuitively plausible that earlier mental states cause later ones directly, but what could we make of the idea of adjacent mental states? Of course, as McGinn acknowledges, we can give a physical location to consciousness by identifying the brain which seems to support it, or by pointing out the physical objects to which we consciously attend: we can even point out that our pains seem to have pretty specific locations. But none of these points really touches the claim that consciousness in and of itself is no more located in space than, say, the number three. Nor, says McGinn, can we assume that consciousness exists in a kind of space we’re merely unused to thinking about, as we do with some of the entities of physics: entities we never directly experience, but believe in because they are part of the best available explanation of the data. The physical properties of consciousness are mysterious in a different, and less tractable sense, than the physical properties of, say, electrons.

Sophie R Allen, in a recent JCS piece (‘A Space Oddity’, Volume 13 No.4) has launched a limited but two pronged attack on this position. Her main objection is to the idea that time can be regarded as ontologically separate from space. She examines four different conceptions of the relationship between space and time: standard relativity, Michael Tooley’s diluted relativity (he apparently adds a privileged frame of reference, which seems to me a flat contradiction of the main idea); the views of Quentin Smith, and the traditional view of time as absolute. This is not a very comprehensive sampling of philosophical views about time, and the last two don’t even seem to support Allen’s case – both allowing a separation of space and time. She might perhaps have mounted another, pseudo-Leibizian argument: time is all about change, and without physical extension, no change is possible, ergo you can’t have time without space. As it is, much the strongest of her arguments comes from orthodox relativity, partly because it is orthodox and authoritative, and partly because it really does involve abolishing the separation of time and space.

Even on that ground, however, I don’t think McGinn need be unduly troubled. He could say that relativity applies only to physical entities – whether it applies to mental ones is an open question. It may well apply to us as physical animals, but we don’t consciously experience time as relativistic. In fact, the gap between modern physics and our intuitive idea of the world is explicitly part of McGinn’s argument. He points out that the progress of physics has taken our scientific view of the world gradually further and further from the ‘folk’ view (it’s not just relativity – even the principles put forward by Galileo and by Newton are in some respects counter-intuitive). Isn’t it likely, he says, that we need one more big leap to an even less common-sensical idea of the world – one which would encompass consciousness, but one which we are, alas, unfitted to make?

Allen, in fairness, does not claim to demolish McGinn’s position, only suggest that it is unconvincing. However, to make much headway she really needs to establish that the idea of things existing in time but not space is more or less incoherent. I don’t think it is: what about Christmas, for example?

The second prong of the attack is directed towards restoring the analogy between mental events and the unseen entities of physics. McGinn points out that while elementary particles and the like may be mysterious in some respects, we do conceive of them as existing in space and entering into broadly the same kind of spatial relationships as macroscopic entities (personally I can’t help thinking in billiard-ball terms): mental entities are utterly different: they don’t collide or exclude each other from spaces, or form triangles, or anything like that.

Yes, but, says Allen: how do we know that electrons and the rest operate in space? Only because they appear to have effects on familiar spatial objects which we can observe directly: and as a matter of fact, the spatial properties of some of these microscopic physical entities are decidedly queer and unlike those of the objects we see around us. Why shouldn’t similar observations apply to mental entities? We know about them through their physical effects (at least in the case of other people), so they seem to have at least a nodding acquaintance with the physical world: why shouldn’t they exist in some space (perhaps slightly deviant) of their own?

Fair enough – but the whole of this argument is, of course, something of a side-show. Even if we reject the analogy with the unseen entities of physics, we may still adhere to the idea that consciousness exists in a special space of its own. It doesn’t have to be ordinary space – it might be a superficially plausible idea, for example, that each consciousness exists in its own quasi-solipsistic one-dimensional space (though perhaps harder to say clearly exactly what that would entail).

Allen concludes that McGinn may be right in thinking that we need a further paradigm shift in order to understand consciousness, but that he is altogether too pessimistic about our ability to achieve it. It’s hard not to agree: why shouldn’t we be able to crack the problem eventually?

But McGinn has a further argument up his sleeve. Citing P.F.Strawson, he suggests that our whole cognitive apparatus is based on spatial concepts. Fundamental ideas such as identity are rooted in ideas about ‘being in the same place’. When we come to consciousness, therefore, we cannot avoid thinking about it spatially: but because it is non-spatial that means we are doomed to incomprehension.

This is a seductive, if depressing argument: but I have the same reservations about it as I do about McGinn’s general thesis. If we were subject to cognitive closure in respect of consciousness, we should certainly be unable to solve the problem, but it seems to me we should equally be unable to perceive the problem. If our thinking were irredeemably spatial, we would happily work out whatever aspects of consciousness were amenable to such thinking, and never notice the rest. If the non-spatial aspects had spatial consequences, we should perceive them as independent spatial phenomena. We might indeed be forced to come up with some new, apparently arbitrary physical laws or constants, but we shouldn’t find anything profoundly inscrutable. Let’s not give up yet.