critique-of-pure-reason.com

29 October 2010

The Dream and The Malicious Demon

In my first look at Descartes’ Meditations, I came to the conclusion that the dream argument is too complicated to serve as the perfect scepticism that Descartes is looking for. Although it can be formulated to be equally as devastating as other hypotheses – and Crispin Wright treats them all as effectively equivalent – still there is something superflous about it, something that seems to give us a measure of anti-sceptical purchase.

Most obviously, in arguing that I cannot tell the difference between waking and dreaming you are taking for granted that difference; you presuppose that there is such a thing as waking. We are tempted to compare our current state of wakefulness with the erratic, surreal world of dreams, thus finding it implausible to think we could be doing philosophy in our sleep. To me this response does not seem sufficient to defeat the argument, because that we are dreaming in a sense (the sense intended by Descartes, in fact) does not actually depend on there being any such thing as waking. The distinction is one way of describing impressions that appear to be perceptions of an external world but which are in fact illusions. The dream argument does use the difference between dreaming and waking – it persuades us with its use of familiar facts – but it does not depend on it.

Peter Simpson makes this point in “The Dream Argument and Descartes’ First Meditation.” He notes that Descartes does not presuppose the difference between dreaming and waking in quite the same way as his conclusion states the possibility that there might be no such difference. The dream argument could be described as going like this:

If the distinction is genuine, there must be some difference that enables us to establish this with certainty; on examination one finds that this is not the case…So, contrary to appearances, the distinction is not genuine after all.

Simpson thus believes that this criticism of the dream argument – that it is inconsistent owing to the presupposition of a distinction between dreaming and waking – does not work when attacking Descartes’ premise that we cannot tell the difference between the two.

However, he does believe that the criticism works elsewhere. He analyzes the dream argument as follows:

(1) There are no certain indications for distinguishing dreaming and waking.
[(1a) If there are no such certain indications, then I might now be dreaming.]
(2a) Therefore I might now be dreaming,
(2b) and what I am experiencing are false delusions

As we have seen, (1) is not as inconsistent as it seems at first, but Simpson points out that the bracketed conditional (1a) – which he takes to be implicit in the dream argument, for otherwise (2a) and (2b) could not follow – must be false. If there are indeed no such certain indications, then we have no justification for thinking that the terms 'dreaming’ and 'waking’ are not synonymous. One cannot say “then I might now be dreaming,” because one is depending here on the distinction, which (1) shows cannot be ascertained. In saying so one is saying that there is an opposing state of being awake, and this is precisely what (1) prevents one from doing.

Simpson doesn’t mention the demon, but it seems to me that his analysis works equally well against it.

It might be interesting to compare Simpson’s succinct demolition of the dream argument with Crispin Wright’s much more elaborate “implosion.” Wright frames the argument in terms of warrant and belief, rather than knowledge, but it will be simpler here to present it, taking the cue from Stroud, in terms of knowledge.

Where K(x) means “I know that I am x,”

(1) ¬K(not dreaming)
(2) K(writing) → K(not dreaming)
∴ ¬K(writing)

I do not know that I am writing.

Wright goes on to show that the argument calls into question the faculties that it requires to be consistent, and therefore that it is groundless. Might the effort at revealing this “implosion” have been avoided if he had accepted Simpson’s criticism? I’m not sure about this. It’s not immediately apparent how Simpson’s criticism would demonstrate the inconsistency of Wright/Stroud’s formulation.

In any case, I don’t find Simpson’s criticism convincing. What is at issue is whether we can tell the difference between perceiving, and seeming to perceive. To say that we cannot tell the difference at any particular time is not to say that we do not know what the difference is, or that the distinction is not meaningful. If we cannot tell at any time which it is we are sensing, then we can say that we might at any moment be only seeming to perceive. This conditional consequent does not depend on our being able to tell what the difference is, at any particular time – which is the only dependency that could render the conditional false. Rather, it is simply establishing the possibility that all is not what it seems at a particular moment, and on the face of it Descartes does this successfully.

If this is right, then the dream argument is immune to all similar criticisms to the effect that it presupposes the distinction between dreaming and waking.

The Demon

Anyway, all of these confusions illustrate what Descartes knew, which was that although there must be a single devastating form of the argument, the dream argument was not best way of presenting it.

Descartes’ explicit reason for going beyond the dream argument is that it leaves his mathematical beliefs intact. These beliefs are not dependent on his senses, so he finds that he cannot doubt that 2 + 3 is 5 or that a square has four sides. Moreover, he is entitled on this basis to believe in a world in which mathematical ideas have meaning – a world in which number and dimension can apply to things.

To extend the doubt, therefore, he moves on from dreaming to ask if it might be the case that this mathematical knowledge is not knowledge at all; that God has fooled him by giving him false a priori notions. Dreaming cannot remove all certainty, but perhaps a deceiving God could do so.

...how do I know that God has not brought it about that I…go wrong every time I add two and three or count the sides of a square…

After some reflection he decides that this is indeed the best route to ultimate scepticism, but he draws back from hypothesizing that God is the culprit, because he is “supremely good and the source of truth.” Instead, he imagines that all of his beliefs are the work of an all-powerful deceiver.

I will suppose…that some malicious demon of the utmost power and cunning has employed all his energies in order to deceive me.

Nothing that appears to him is real, including his own body, and he has also been fooled into believing in a priori notions such as those of mathematics, which had until now seemed the most certain beliefs of all. Thus, he can imagine that there is no external world, that there is nothing physical at all, that he does not exist in the way he thinks he does, and that all of his memories are fictions, and that his most certain beliefs, even those that appear to be self-evidently true, are deceptions.

Wright Reconsidered

I like Wright’s response to radical scepticism, but I’ve been wondering if it’s not just another form of what he calls the “Russellian Retreat,” which is to admit that you cannot be absolutely certain of the existence of the external world – or, at least, that you cannot prove it – but that we nevertheless have no good reason to favour the sceptical hypotheses over the beliefs we can justify with inference to the best explanation. Wright’s conclusion is that the ultimate sceptical argument doesn’t work, because it leads to its own denial; and further, that we also have grounds for denying it. This sounds quite close to saying, as Russell did, that we have no reason to believe it. And he similarly fails to positively establish that we have justification for the belief that we are not now being deceived, and falls back on hinge-propositions: “I am not now being deceived by a demon” as a bedrock belief that cannot be doubted.

That analysis is not quite right. Wright formulates the sceptical argument in terms of warrant, specifically to block the Russellian Retreat. We cannot comfortably give up our claim to have warranted beliefs in the way that we can give up our claim to knowledge. Unlike Russell, Wright beats the sceptic without giving up the epistemic notion under attack.

There is a difference between, on the one hand, dismissing scepticism negatively or dodging it with the Moore shift; and, on the other hand, showing that it is inconsistent. It is the latter that Wright succeeds in doing, in my opinion. It appears that we really have made progress: as it turns out, we have good grounds for rejecting scepticism on its own terms.

Even so, there is no positive proof of the external world. In fact, it looks like there never could be one, unless you think you can build one, like Moore, on the basis of the very knowledge that mild scepticism successfully doubts.

This leads me to something else that occurs to me. Wright’s project is to defeat the strongest possible sceptical argument, the most radical scepticism, and to that end he formulates the argument in terms of warrant rather than knowledge. A sceptical argument to the effect that I do not know that I am sitting at my computer writing allows for the Russellian retreat; it is mild scepticism. There is something about this that has been troubling me.

It may be mild in that it does not threaten our beliefs, which we feel justified in holding. But in one sense it is not mild at all: if it cannot be defeated; if the only thing we can do is flatly conradict it, as Moore did, and say, “but I know I’m sitting at my computer writing”, or retreat from it, as Russell did, and say, “alright, you’ve got me, but I have no reason at all to believe your hypothesis”; then isn’t it the strongest scepticism of all? How would Wright’s approach work with the argument in terms of knowledge? I suppose his whole strategy is based on the observation that we can justifiably reject this “mild” form of scepticism; and that this justification is not, on the face of it, enough to give us grounds to reject the “radical” argument, thus launching him on the task of exposing the “implosion.”

This so-called mild scepticism, then, still might have the power to haunt us. I do not mean that we cannot justifiably reject it, but that it can be posed repeatedly and seem to demand an answer, because any rejection is something of a retreat (Russell) or maneuver (Moore); or if it is a more direct response (Wright), it tackles only the more threatening version of scepticism.

Wright’s formulation has been criticized, mainly to the effect that his scepticism does not even get off the ground, and thus leaves little to trouble us; but I want to avoid getting caught up in the detailed debates at this stage.*

At some point I’ll be looking at the cogito, but I haven’t quite finished with the dream or the demon. Next I hope to look at Barry Stroud’s treatment of the subject in The Significance of Philosophical Scepticism.

*See Pritchard (2001) and Brueckner (1992)

Simpson, P. 1982: “The Dream Argument and Descartes’ First Meditation”, Auslegung 9 (available here)
Wright, C. 1991: “Scepticism and Dreaming: Imploding the Demon”, Mind, vol. 100, pp87-116
Descartes, R. 1996: Meditations on First Philosophy, Cambridge University Press
Stroud, B. 1984: The Significance of Philosophical Scepticism, Oxford University Press

comments powered by Disqus