On Certainty

I am sitting with a philosopher in the garden; he says again and again 'I know that that’s a tree', pointing to a tree that is near us. Someone else arrives and hears this, and I tell him: 'This fellow isn’t insane. We are only doing philosophy.

I act with complete certainty. But this certainty is my own.

At the core of all well-founded belief lies belief that is unfounded.

If you tried to doubt everything you would not get as far as doubting anything. The game of doubting itself presupposes certainty.

Where two principles really do meet which cannot be reconciled with one another, then each man declares the other a fool and a heretic

If a blind man were to ask me “Have you got two hands?” I should not make sure by looking. If I were to have any doubt of it, then I don’t know why I should trust my eyes. For why shouldn’t I test my eyes by looking to find out whether I see my two hands? What is to be tested by what?

What is the proof that I know something? Most certainly not my saying I know it.

What stands fast does so, not because it is intrinsically obvious or convincing; it is rather held fast by what lies around it.

476. Children do not learn that books exist, that armchairs exist, etc.,etc. - they learn to fetch books, sit in armchairs, etc.,etc. Later, questions about the existence of things do of course arise, "Is there such a thing as a unicorn?" and so on. But such a question is possible only because as a rule no corresponding question presents itself. For how does one know how to set about satisfying oneself of the existence of unicorns? How did one learn the method for determining whether something exists or not? 477. "So one must know that the objects whose names one teaches a child by an ostensive definition exist." - Why must one know they do? Isn't it enough that experience doesn't later show the opposite? For why should the language-game rest on some kind of knowledge? 478. Does a child believe that milk exists? Or does it know that milk exists? Does a cat know that a mouse exists? 479. Are we to say that the knowledge that there are physical objects comes very early or very late?

471. It is so difficult to find the beginning. Or, better: it is difficult to being at the beginning. And not to try to go further back.

I want to say: We use judgements as principlesof judegement.

I believe it might interest a philosopher, one who can think himself, to read my notes. For even if I have hit the mark only rarely, he would recognize what targets I had been ceaselessly aiming at.

All testing, all confirmation and disconfirmation of a hypothesis takes place already within a system. And this system is not a more or less arbitrary and doubtful point of departure for all our arguments: no, it belongs to the essence of what we call an argument. The system is not so much as the point of departure, as the element in which arguments have their life.

My life consists in my being content to accept many things.

In order to make an error, a man must already judge in conformity with mankind.

Certainty is as it were a tone of voice in which one declares how things are, but one does not infer from the tone of voice that one is justified.

I am now doing philosophy like an old woman, who keeps on mislaying something and then has to look for it again - sometimes her glasses, sometimes her key-chain

383. The argument "I may be dreaming" is senseless for this reason: if I am dreaming, this remark is being dreamed as well - and indeed it is also being dreamed that these words have any meaning.

But doesn't it come out here that knowledge is related to a decision?

95. The propositions describing this world-picture might be part of a kind of mythology. And their role is like that of rules of a game; and the game can be learned purely practically, without learning any explicit rules. 96. It might be imagined that some propositions, of the form of empirical propositions, were hardened and functioned as channels for such empirical propositions as were not hardened but fluid; and that this relation altered with time, in that fluid propositions hardened, and hard ones became fluid.

Giving grounds, however, justifying the evidence, comes to an end; but the end is not certain propositions striking us immediately as true i.e. It is not a kind of seeing on our part; it is our acting which lies at the bottom of the language game.

That I am a man and not a woman can be verified, but if I were to say I was a woman, and then tried to explain the error by saying I hadn't checked the statement, the explanation would not be accepted.