QuestionsCan we be certain of anything?Whereof one cannot speak, thereof one must be silent
Can we be certain of anything?What escapes words

Whereof one cannot speak, thereof one must be silent

Ludwig Wittgenstein 1889 · 1951The limits of my language mean the limits of my world.
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What it claims

About value, ethics and the sense of the world, one must be silent: it cannot be said, it shows itself.

Why

A sentence makes sense only if it states a possible fact, and value and the meaning of the world are not facts.

In short

"Whereof one cannot speak, thereof one must be silent" is an argument by Ludwig Wittgenstein (Tractatus, 4.01, 6.41, 6.54, 7) on the question "Can we be certain of anything?" (answer: what escapes words). Its claim: About value, ethics and the sense of the world, one must be silent: it cannot be said, it shows itself. According to AskPhilosophy's logic check (Z3 solver), the argument is valid only if one grants a premise the author leaves unstated (P3). AskPhilosophy presents 2 objections, 1 of them with a documented reply, and the original text behind each premise, checked word for word.

Tractatus, 4.01, 6.41, 6.54, 7
Valid with an implicit premise

The last sentence of the Tractatus is one of the most famous in philosophy. It does not say "keep quiet when you don't know". It draws a boundary: on one side, what can be said, the facts; on the other, what can only show itself, value, ethics, the meaning of life. It is often compared to the first line of the Daodejing ("the Dao that can be spoken is not the constant Dao"): the echo is striking, but no influence is known, and the thesis differs. Laozi speaks of an origin of the world that names cut up; Wittgenstein speaks of the limit of all meaningful language, and describes nothing beyond it. This is the early Wittgenstein's thesis: the later one will call it into question.

P1A proposition has sense only if it is a picture of a possible fact: it says how things are in the world.
P2Yet the sense of the world, value and ethics are not facts in the world: in the world "there is no value"; the sense of the world "must lie outside the world".
P3 · implicit premiseWhat cannot be said with sense should not be put forward as a claim: one would only produce senseless propositions. The right method in philosophy is to say only what can be said, and to show anyone who wants to say something else that he has given no meaning to some of his words.
Therefore about value, ethics and the sense of the world, one must be silent: it cannot be said, it shows itself.

click a premise to reject it

If you accept every premise, logic forces you to accept the conclusion. So the debate is about the premises.
Checked by a logic solver: the premises cannot all be true while the conclusion is false.
Without the implicit premise: Without P3, the computer finds a world where ethics lies outside the world and cannot be said with sense, but where nothing requires silence: one could go on putting forward theses about ethics, while knowing they have no sense.
Valid with P3. P1 and P2 are enough to conclude that these subjects cannot be said; P3 is needed to go from "cannot" to "must be silent". Wittgenstein does not write it as one sentence, but it follows from his view of philosophy as clarification (4.112) and from "the only strictly correct method" (6.53). This "must" is not a moral ban: being silent means putting forward no thesis where none has sense. The real difficulty lies elsewhere: P1 is not itself a picture of a fact. Applied to the book, it makes the book senseless. Wittgenstein knows it and accepts it (6.54). Two readings clash here. The traditional reading (Anscombe, Hacker): there is a real unsayable (value, logical form) that shows itself. The "resolute" reading (Cora Diamond, James Conant, around 1990-2000): there is nothing behind these sentences, and the book aims to cure us of them. We present the argument in the first, more widespread reading; the second is recalled under Ramsey's objection.
Analogy. A camera can photograph everything in front of it, except the point of view from which it shoots. That point of view appears in no photo, and yet it shows in all of them. For the Tractatus, language is the camera, facts are what it photographs, and value is like the point of view: not one more thing in the picture.

Objections

2

Each objection is a conversation: click to see who replies and where the debate stands.

Bertrand Russell, introduction to the Tractatus 1922 · attacks premise 1

Wittgenstein "manages to say a good deal about what cannot be said". This suggests there may be a way out: what a language cannot say about itself, another language, which speaks about the first, might say, and so on without limit.

Wittgenstein replies
Wittgenstein Wittgenstein's anticipated reply (Tractatus, 6.54, written before Russell)
His own propositions are elucidations: whoever understands him finally recognises them as senseless, once he has climbed through them, on them, over them. He must so to speak throw away the ladder after he has climbed up it.
The debate goes on (our summary) The ladder answers the first charge (saying what cannot be said): Wittgenstein grants it and accepts it. It does not answer the second idea, the hierarchy of languages. Russell himself foresees the reply (the theory would apply to the totality of languages) and admits his hypothesis is "very difficult". But the hierarchy of languages became a standard tool of logic (Tarski, 1933), where one speaks without contradiction about one language in another. As for the defence by "showing", Russell says it may be adequate, but confesses "a certain sense of intellectual discomfort".
F
Frank Ramsey 1931 · attacks the conclusion

"What we can't say we can't say, and we can't whistle it either." If sentences about ethics or the mystical are truly senseless, there is nothing behind them that "shows itself": the unsayable is not a hidden content, it is an absence of content. (A remark written around 1929, published in 1931 after Ramsey's death; his text is not yet in our corpus.)

no reply
summary: their text is not yet in our corpus
We have not yet found a direct reply by Wittgenstein in the texts.
The debate goes on (our summary) We have found no direct answer to this sentence. In the preface to the Investigations (1945) he only writes that Ramsey's criticism helped him, "to a degree which I myself am hardly able to estimate", to recognise grave mistakes in the Tractatus. There is no agreement on what these "grave mistakes" are: surely the idea of a general form of all propositions (Investigations, §114), less surely the boundary between saying and showing. For the so-called "resolute" reading (Cora Diamond, James Conant), Wittgenstein already thought like Ramsey: in the Tractatus there would be nothing unsayable that shows itself, and the image of the ladder invites us to grasp this. For the traditional reading (Peter Hacker), the book speaks too often of what "shows itself" for this to be a trick: Ramsey hits the mark, and Wittgenstein later acknowledged it. The debate remains open.