Wittgenstein, On Certainty

1. Introduction

Wittgenstein (1889–1951)

– Tractatus Logico-Philosophicus (1921/22): language and reality; general form of the proposition; sense and nonsense; idealism and solipsism; nature of philosophy; ineffability and mysticism

Philosophical Investigations (1953): family resemblance; language games; private languages; rule-following; forms of life; aspect perception; philosophy as therapy

Posthumous publications: Remarks on Colour; Remarks on the Philosophy of Psychology; Zettel; The Foundations of Mathematics; On Certainty

W1      An extraordinary thing has happened to me. About a month ago I suddenly found myself in the right frame of mind for doing philosophy. I had been absolutely certain that I’d never be able to do it. It’s the first time after more than 2 years that the curtain in my brain has gone up. [Quoted in Malcolm 1984: 134]

On Certainty unrevised writings (broadly, on questions in epistemology), from the last 18 months of W’s life. Stimulated by GE Moore’s ‘Proof of an External World’ and ‘A Defence of Common Sense’. Remarks very rough, unfinished, barely edited; first thoughts that W may well have revised if he had survived. Interpretatively challenging; hard to understand without some understanding of (at least) PI.

2. Moore’s proof of the external world

P1. Here is one hand.
P2. Here is another hand.
P3. Two human hands exist. [From P1 and P2]
C. External objects exist.

Objection: Does it beg the question?

W2      If Moore is attacking those who say that one cannot really know such a thing, he can’t do it by assuring them that he knows this and that. For one need not believe him … Moore’s mistake lies in this – countering the assertion that one cannot know that, by saying ‘I do know it. [OC 520–1]

Moore: As rigorous as any other proof; how else would we prove ‘There are at least three typos in §1’?

W3      When one says that such and such a proposition can’t be proved, of course that does not mean that it can’t be derived from other propositions; any proposition can be derived from other ones. But they may be no more certain that it is itself. [OC 1]

= P1, P2 less certain (i.e. we’re more likely to be mistaken about it) than about C; if we were unsure of C, assertion of P1, P2 not convincing. This argument can’t extend our knowledge.

3. Two kinds of doubt

Practical doubts: Doubts internal to ordinary discourse on (e.g.) knowledge, justification.

Further doubts: Doubts for which there’s no provision in ordinary life.

Compare: ‘I know this is a hand’ said during a party game in a dark room vs the same sentence uttered in a philosophy seminar. ‘Yes, you know by ordinary standards but not by these stricter standards.’

How to respond to the sceptic? Not enough to assert that philosophical doubt is illusory, but to show it.

4. Moorean propositions

Moore’s ‘list of truisms’ which ‘I know, with certainty, to be true’: ‘There exists at present a living human body, which is my body. This body was born at a certain time in the past, and has existed continuously ever since … Ever since it was born, it has been either in contact with or not far from the surface of the earth…’

W’s list: ‘All human beings have parents’, ‘Motor cars don’t grow out of the earth’

W4      These propositions belong to the ‘world-picture [that] is the substratum of all [one’s] enquiring and asserting [OC 162]

W5      Moore’s propositions ‘have a peculiar logical role in the system of our empirical propositions’. But it is wrong to say that he ‘knows their truth’. [OC 136–47; emphasis added]


(1) If someone says he knows something, he can answer the question ‘How does he know?’; We can’t answer the question of how we know the Moorean propositions – we can’t give grounds for believing them more certain than the propositions themselves. Therefore, we’re not correctly described as knowing them. Knowledge the wrong word to use for our relation to these propositions.

(2) The statement ‘I know this is a hand’ only makes sense in certain contexts (e.g. the party game, a waxwork museum, etc). Elsewhere, it’s ‘nonsense’.

5. ‘Hinge’ propositions and a ‘world-picture’

W6      The questions that we raise and our doubts depend on the fact that some propositions are exempt from doubt, as it were like hinges on which those turn [OC 341]

Similarly, he speaks of a body rotating on an axis:

W7      I do not explicitly learn the propositions that stand fast for me. I can discover them subsequently like the axis around which a body rotates. This axis is not fixed in the sense that anything holds it fast, but the movement around it determines its immobility. [OC 151–52]

Moorean propositions together make up a ‘world-picture’.

W8      I did not get my picture of the world by satisfying myself of its correctness; nor do I have it because I am satisfied of its correctness. No: it is the inherited background against which I distinguish between true and false. [OC 94]

W’s position a kind of anti-intellectualism about Moorean propositions: not acquired by following some rational belief-forming method; rather, simply ‘inherited’. Further, our grasp of Moorean propositions is not best understood as quasi-perceptual, but as related to action:

W9      … it is our acting, which lies at the bottom of the language-game. [OC 204]

6. W’s Anti-foundationalism

For W, justification comes to an end, but not in basic, self-evident beliefs. Rather in propositions that ‘stand fast for us’. But:

W10    .. what stands fast does so, not because it is intrinsically obvious or convincing; it is rather held fast by what lies around it. [OC 144]

The certainty we have about Moorean propositions is

W11    … something that lies beyond being justified or unjustified; as it were, as something animal. [OC 359]

And this (pace the philosophical sceptic) is not a problem, nor a failing on our part. Cf:

W12    … to use a word without a justification does not mean to use it wrongfully [PI §289]

W13    Whenever we test anything, we are already presupposing something that is not tested [OC 163]

W14    One cannot make experiments if there are not some things that one does not doubt [OC 337]

7. Analogy with mathematics, rules of game

– Origin of rules of addition from primitive counting: we decide that nothing will count as falsifying (say) ‘5+7=12’. Any other answer must be a case of miscounting.

– Absurdity of demanding justification for how the knight moves in a game of chess: just laid down as part of what it is to play chess.

W: Maybe Moorean propositions are ones we treat as ‘norms of description’ [OC 167], i.e. ‘I am not ready to let anything count as a disproof of this proposition’.

But this is not a psychological point (again, cf chess), but a logical one. To know how to play this game just is to treat this rule as unquestionable, because partially constitutive of the game.

8. Disanalogies with mathematics

(1) Mathematical propositions everywhere incontrovertible, but Moorean props may be called into question in sufficiently unusual contexts.

(2) Nothing can change the certainty of mathematical propositions; but Moorean props may come to lose their status as unquestionable.

W15    It might be imagined that some propositions, of the form of empirical propositions, were hardened and functioned as channels for such empirical propositions, were hardened and functioned as channels for such empirical propositions as were not hardened by fluid; and that this relation altered with time, in that fluid propositions hardened, and hard ones became fluid. [OC 96]

In other words,

W16    … the river-bed of thoughts may shift. But I distinguish between the movement of the waters on the river-bed and the shift of the bed itself; though there is not a sharp division of the one from the other.

E.g. ‘No one has ever been on the moon’ (basic in 1950/51, not after 1969)

9. Relativism?

Worry: If statements can only be assessed against the background of a “world-picture”, how are we to assess some particular ‘world-picture’ itself? [Cf Kuhn on scientific paradigms] Imagine a certain community:

W17    Instead of the physicist, they consult an oracle […] If we call this ‘wrong’ aren’t we using our language-game as a base from which to combat theirs? [OC 609]

W18    I said I would ‘combat’ the other man, – but wouldn’t I give him reasons? Certainly; but how far do they go? At the end of reasons comes persuasion. (Think what happens when missionaries convert natives.) [OC 612]

Strong strains of radical relativism in W:

W19    We should feel ourselves intellectually very distant from someone who said this [sc. some people have gone to the moon, but we don’t know how they got there and how they survived].

W20    One might simply say ‘O, rubbish!’ to someone who wanted to make objections to the propositions that are beyond doubt. That is, not reply to him but admonish him. […] This is a similar case to that of showing that it has no meaning to say that a game has always been played wrong. [OC 495–96]

Disanalogy: Rules of a game answerable to nothing beyond themselves; (many) Moorean propositions are so answerable.

Wittgenstein sometimes happy to assert that some world-pictures are better than others. E.g.:

W21    If we compare our system of knowledge with theirs then theirs is evidently the poorer one by far. [OC 286]

Recommended readings

Marie McGinn, Sense and Certainty (Oxford: Blackwell, 1989).

Crispin Wright, ‘Wittgensteinian Certainties’, in D McManus (ed.) Wittgenstein and Scepticism (London: Routledge, 2004).

P. F. Strawson, ‘Scepticism, Naturalism and Transcendental Arguments’, in Scepticism and Naturalism: Some Varieties (London: Methuen, 1985).