194. ‘With the word “certain” we express complete conviction, the total absence of doubt, and thereby seek to convince other people. That is subjective certainty.
But when is something objectively certain? When a mistake is not possible. But what kind of possibility is that? Mustn’t mistakes be logically excluded?’ (Ludwig Wittgenstein, ‘On Certainty’)
I will confess right off the bat that I have no idea what Wittgenstein means by his final sentence here. Maybe I can come to some kind of understanding by working through this proposition.
What kind of fact logically excludes mistakes? The fact that I exist? On Certainty is a sustained mediation on (duh) certainty – the opening line is the famous Moore quote about knowing that there is one hand in front of you. Wittgenstein goes into a very long and in my opinion needless exploration of the mental workings behind certainty on topics such as this. This, I think, is misguided. My response is typically, what reason have I to doubt that my I exist, that I am real, that the world is real? That’s my typical response to what I would regard as scepticism beyond necessity – if one requires hundreds of pages of tortured groping for whether one can be certain that they, or the world or their hand exists, I suspect that there are more important problems for said sceptic to attend to.
However, to think a bit more on this notion: what is meant by logically excluding mistakes? On the surface, it would appear simple: something is certain when its negation is logically impossible. The world exists – this excludes the possibility of mistakes. We may be mistaken as to the nature of the world, or something along those lines, but we cannot be mistaken that there is a world, because if there wasn’t, there wouldn’t be. This seems to me to actually be quite unhelpful – Wittgenstein’s tortured method seems to be contagious.