On Certainty is the first Wittgenstein text I read cover to cover – in fact, I seem to remember reading it twice feverishly over one weekend. It’s more a collection of notes than a worked-up text and it is slightly infuriating – you keep thinking he has got the issue sorted and then he starts at it again and the solution goes out of focus. Wittgenstein seems to have had a similar feeling – using a not very politically correct metaphor, he noted: “I do philosophy now like an old woman who is always mislaying something and having to look for it again; now her spectacles, now her keys” (OC para 532).
So what is it all about? The most obvious philosophical target is probably Descartes, but the line of thought is very natural in our culture (and probably more widely). In our search of certainty, the temptation is to start from the apparently undeniable reality of our own immediate experience, but it is hard to build out from this starting point. It may seem clear that I cannot doubt my own existence and what I am experiencing now, but my beliefs about my past seem open to doubt as do claims about other’s people’s experiences or even claims about other people’s existence and the existence of anything outside my own immediate experience. Once we start thinking along these lines, it seems hard not to conclude that the only thing I can be absolutely certain about, the only thing that is definitely real, is what I am experiencing now.
This seems a bit odd. We start out looking for absolute certainty and end up losing virtually everything While a lot of continental philosophers have embraced this paradox with enthusiasm, pragmatic Anglo-Saxons have found the situation much less satisfactory. The English philosopher G.E.Moore sought to brush the problems away through the brute assertion of common sense: he held up a hand, declared that he knew his hand existed and argued that since his hand existed, so did the external world. As a philosophical proof, this seems pathetic or hilarious depending on how you look at it. As Friedrich Waismann remarked, “What can one say to [Moore] – save perhaps that he is a great prover before the Lord”. But Wittgenstein thought Moore was onto something – or at least was highlighting in a striking way an important set of philosophical confusions. Moore claims to know that the world exists and we want to agree, but how does he know this? He seems right to separate this claim from most of his other beliefs, and it certainly seems far more certain than all sorts of other things he holds to be true, but its foundational nature seems to make it both hard to question and also hard to support. What we “know” and hold to be most certain seems unsupported and unsupportable rather than the claim we have the best possible support for.
It is no use for Moore to keep emphasizing that he knows. Knowing something is not a mental state that we ascribe to ourselves via introspection, so Moore’s certainty proves nothing. If I say “I know Philadelphia is nearer Washington than New York is” and you disagree with me, we don’t try to resolve the issue by my focusing intensely to try to see whether or not I am indeed in the mental state of knowing. Rather we check the truth of the claim itself and then conclude either that I do know what I claim to know or that I am mistaken. In this sort of context, if we are arguing and I say: “But I know this” either this is just a way of asserting my view or it means something like “I have reasons for making this claim that you would recognise as giving me a right to certainty”. So, for example, if I had lived in Philadelphia for ten years, you might well accept that I know or if I tell you that I have just checked this fact on Google, you might agree to view the argument as settled (despite the fact of course that in either case error is still possible!). The difficulty with Moore’s claim, however, is that interpreting his “I know” as meaning: “I have reasons for making this claim that you would recognise as giving me a right to certainty” does not get us anywhere. Firstly, this is the heart of the debate. And secondly, it would be ridiculous to suggest that Moore is in any way better qualified to make this claim than anyone else. This is precisely not a situation where someone can say: trust me on this because I am in a better position to decide this issue than you are!
Moore talks about knowing that the external world exists, but there are all sorts of claims that seem similar – e.g. “I know I have a body”, “I know I have never been to the moon”, “I know there is a brain inside my head”. Here again we seem to know something and it seems pretty certain, but we don’t have anything we can point to as grounds for this knowledge. If we widen the discussion, however, the flicker of a solution arises, for we might well start to ask ourselves: when does it make sense to doubt? Consider the opposite of one of the claims I just mentioned: how would we react if someone said: “I don’t know if I have a body or not”? It is very hard to imagine circumstances where we would know what to do with this claim and that’s the point – in real life, raising a doubt has a purpose and doubt leads somewhere. If I say to my friend “I don’t know if I can move my legs”, my friend will ask “why have you had an accident? Are you feeling unwell?” and if I say, “No, it is just a philosophical doubt”, they will think I am being annoying or making a joke. The strange thing about philosophical doubt is, on the one hand, that it seems to pop up in the most peculiar places and on the other, that it does not really seem to have any consequences. “I don’t know if I can walk, but I am still planning to play tennis on Saturday”!
So we can see at least part of the solution. Our picture of doubt turns out to be misleading. You can’t just doubt everything; rather you need grounds for doubt. If I suddenly say, “perhaps I have only got one kidney”, then others will only take me seriously if something has happened to prompt this doubt. Similarly, doubts have consequences. If I say: “I doubt whether I will live beyond 50″, then you will be surprised if I spend a lot of time thinking and planning about my retirement. These points about doubt and doubting are all very familiar to us – we know how to use the phrase “I doubt” and we know what doubting involves, but when we start doing philosophy, we think we can generalise doubt and then get confused when we run into difficulties. It is as if we argue: “I can doubt whether I will be home in time for dinner, so surely I can increase my scepticism a bit and doubt whether the world exists!”.
Obviously, this is nowhere near a complete solution, for one thing we have not talked about all the confusions embedded in our confident talk of an inner world that is beyond doubt. And then there are other puzzles. For example, it is amusing but slightly disconcerting that Wittgenstein talks about our knowing that it is not possible to travel to the moon, so it seems that these things change. Do we want to say that the statement “I can’t remember if I have been to the moon” was nonsense fifty years ago, is hovering between sense and nonsense today and could make perfect sense in fifty years time? I don’t think so, but that’s a discussion for another day.