The proposition, that your action has such-and-such a cause, is a hypothesis. The hypothesis is well-founded if one has had a number of experiences which, roughly speaking, agree in showing that your action is the regular sequel of certain conditions which we then call causes of the action. In order to know the reason which you had for making a certain statement, for acting in a particular way, etc[.|,] no number of agreeing experiences is necessary, and the statement of your reason is not a hypothesis. The difference between the grammars of “reason” and “cause” is quite similar

24.

to that between the grammars of “motive” and “cause”. Of the cause one can say that one can't know it but one can only conjecture it. On the other hand one often says: “Surely I must know why I did it” talking of the motive. When I say: “we can only conjecture the cause but we know the motive” this statement will be seen later on to be a grammatical one. The “can” refers to a logical possibility.

(2015–) Wittgenstein Source Bergen Nachlass Edition (WS-BNE). Edited by the Wittgenstein Archives at the University of Bergen under the direction of Alois Pichler. In: Wittgenstein Source, curated by Alois Pichler (2009–) and Joseph Wang-Kathrein (2020–). (N) Bergen: WAB.