Known Unknowns

Für Donald Rumsfeld!

When one evening the linguistic philosopher Noam Chomsky remarked at dinner in Trinity College that the foundations of his theory of language were »fundamentally unknowable aspects of the mind,« Sraffa commented sharply: »Then how can you talk about it?«

(Aus: John Eatwell, „Piero Sraffa: Seminal Economic Theorist 1898-1983″, Science & Society, Vol. 48, No. 2 (Summer, 1984), pp. 211-216)

Nachtrag:

In his early work (particularly in the Tractatus Logico-Philosophicus), Wittgenstein used an approach that is sometimes called „the picture theory of meaning,“ which sees a sentence as representing a state of affairs by being a kind of a picture of it, mirroring the structure of the state of affairs it portrays. There is an insistence here – it can be said at the risk of some oversimplification – that a proposition and what it describes must have the same logical form. Sraffa found this philosophical position to be altogether erroneous, and argued with Wittgenstein on the need for him to rethink his position.
According to a famous anecdote, [in 1929] Sraffa responded to Wittgenstein’s claim by brushing his chin with his fingertips, which is apparently readily understood as a Neapolitan gesture of skepticism, and then asked, „What is the logical form of this?“
(…)
The conversations that Wittgenstein had with Sraffa were evidently quite momentous for Wittgenstein. He would later describe to Henrik von Wright, the distinguished Finnish philosopher, that these conversations made him feel „like a tree from which all branches have been cut.“

(Aus: Amartya Sen, “Sraffa, Wittgenstein, and Gramsci”, Journal of Economic Literature, Vol. 41, No. 4 (Dec., 2003), pp. 1240-1255)