I’m teaching epistemology again this year and running through the same anti-sceptical arguments as last year.
- Putnam’s attempt to show that the sceptical ringer is in some sense impossible – because self-refuting – even though it violates no physical law.
- Davidson’s argument that our beliefs must in general be true.
- Williams’ theoretical diagnosis that the sceptic presupposes a substantial and optional theory of knowledge: epistemological realism. Without it, scepticism cannot get off the ground. But it isn’t independently motivated. (And, before we justify scepticism, the fact that epistemological realism implies scepticism is a positive reason to reject it.)
- McDowell’s theoretical diagnosis of scepticism about other minds and suggestion for a similar source for external world scepticism in the argument from illusion and highest common factor view of experience.
- Wittgenstein’s attempt a therapeutic diagnosis of scepticism.
But then the lingering worry returns: the sceptical hypotheses themselves seem to impose more severe ground rules for their assessment. I (and my students) recall that invoking perceptual contact with the world is merely an instance of the kind of test one might merely dream that one were applying and passing. So the returning, lingering worry runs: if it would fail were we asleep, what can it show when we are awake?
In this context, McDowell’s ‘Criteria, defeasibility and knowledge’ (and more recent work) does two things. First, it helps show how a picture of experience – the highest common factor – which might help motivate foundationalism is a) merely optional and b) threatens knowledge even without sceptical ringers (all we need is the possibility of everyday illusion; we don’t also need dreaming or brains in a vat). Second, it provides a further and explicit response to the returning, lingering worry.
The latter follows from the idea of McDowell’s disjunctivism. In the bad disjunct (eg, the case that one is dreaming), one’s apparent worldly experiences are merely appearances (whatever dreams comprise) and hence one cannot have knowledge of the external world because one’s beliefs are in no real relation to it. It would be the merest luck were they true. But in the good disjunct (eg. being awake), perceptual knowledge of the external world – which could, with Williams, also be used to justify the claim that one is not dreaming – is differently constituted. No luck is involved in such perceptually based knowledge (and hence it can be knowledge) because the experiences which justify it are necessarily world-involving.
Now the brighter students are persuaded by this only briefly before they raise the further question: but if one cannot tell the difference between the two disjuncts, how does this account help?
My first response – specifically picking up McDowell’s paper – is to suggest that progress has been made. On the rejected highest common factor account, there can be no perceptually-based knowledge because the best that the experience, on which it is supposed to be based, can do is not enough to rule out the additional need for luck for the beliefs formed to be true. On the proposed disjunctivist view, by contrast, there is no luck involved in the good disjunct so knowledge is sometimes possible (and the bad disjunct realistically implies that attempts to know can also sometimes fail). So if one is in the good disjunct, one does have knowledge.
There are then a couple of typical student responses: the first is to say that the indistinguishability of the disjuncts suggests that there is luck involved in being in the good one in the first place and hence then having world-involving experiences. If I understand McDowell here (and I may not), his reply to this is to concede that there is luck in being in a position to have knowledge (eg. to have a world-involving experience on which to base a knowledge claim) but no further knowledge-undermining luck (since the experience is necessarily world-involving by contrast with being a mere appearance).
The second student response is to say that it only helps to be persuaded (by disjunctivism) that, in the good disjunct, one does have knowledge if one also knows whether one is in that disjunct, rather than the bad one, and hence knows that one knows. Now this is a point that McDowell has addressed in recent papers but the Rodl passage he quotes is as clear a statement. It runs (with some additional carriage returns):
The argument (from illusion) is: Whenever I seem to know something (on the basis of perceptual. experience), I might have been fooled. Had I been fooled, I would not have known that I was. I would not have been able to tell my situation apart from one in which I am not fooled. This shows that my grounds do not place me in a position to exclude that I am in such a situation. They do not enable me to exclude that I am fooled.
—The argument supposes that, had I been fooled, I would have believed the proposition in question on the same grounds on which I believe it now that I am not fooled. This straightforwardly entails that these grounds do not establish the truth of what I believe and therefore do not provide me with knowledge.
But when I know something on the ground that, say, I perceive it to be the case, then I would not, had I been fooled, have believed it on this ground, for, had I been fooled, I would not have perceived it to be the case. Hence, when I am not fooled, my grounds exclude that I am fooled: when I perceive how things are, I am not fooled with regard to how they are.
One might object that this grants me grounds that rule out error at the price of making it impossible for me to know whether my belief is based on such grounds. For, when I am fooled, I do not know that I am fooled. So I can never know whether I am not fooled and my beliefs are based on grounds that [establish] their truth, or whether I am fooled and such grounds are unavailable to me.
This objection repeats the mistake: from the fact that, when I am fooled, I do not know that I am, it does not follow that, when I am not fooled, I do not know that I am not. When I know that p as I perceive it to be the case, then I know that I perceive that p. Thus I am in a position to distinguish my situation from any possible situation in which I would be fooled, for, in any such situation, I would not perceive that p, while in the given situation I do.' [Rodl, S. (2007)Self-Consciousness, Cambridge, Mass.: Harvard University Press pp 157-8]
This passage makes two key points. First, in reply to the students’ second response, in the good disjunct, one knows how one knows and hence, in the good disjunct, one can know that one knows (since how one knows is good enough because necessarily world-involving). Of course, had one been in the bad disjunct, one would have thought that one knew how one knew and that one knew but one would have been wrong on all counts: wrong that one knew (whatever fact about the world) and hence how one knew (it) and hence that one knew that one knew (it). But, second, the fact that, in the bad disjunct, one does not know has no effect on the good disjunct. ‘[F]rom the fact that, when I am fooled, I do not know that I am, it does not follow that, when I am not fooled, I do not know that I am not’.