JKQ > but the idea that beyond his economic achievements, he (Sraffa) also single-handedly changed the course of philosophy ? --unlikely.

SC > Sraffa certainly influenced philosophy through his connection with Wittgenstein.

On what I know I rather side with Jarus on this point.  That the rather sibylline throw away verbal comment drawn for casual conversation with Rees really identified at a moment a change in the course of western philosophy as a whole seems to me just a kind extract from the official ‘myth of Wittgenstein's beatification’ - and not historically credible.

The main point here I judge is how Sraffa and Wittgenstein met – as I recall they were both imported to Cambridge by Keynes - from Italy and Austria respectively - presumably with the specific intention of joining his select discussion group the “Cafeteria Club”.  I do not think we know what was discussed there – and Skidelsky made the point that we do not know what Keynes and Wittgenstein talked about either.  Its all rather mysterious.  We do not know what Popper and Russell talked about straight after the well known poker incident – but we do perhaps get a clue from a radio broadcast Popper made in New Zealand shortly after – rather contra Gelner who tends towards “stupidity”, Popper used the word “charlatanism”.

Regarding Wittgenstein’s influence – probably I would turn not to economics but to matters like his political influence – for instance on the philosopher Collingwood.  Surely “New Leviathan” (1942) directly and strikingly adopts the presentational style of W’s “Tractatus” for its political manifesto?  For instance:

27.29  The ruled class proverbially vult decipi; deceit on the part of rulers if it is for the good of the ruled or for the facilitation of ruling is not only justified; it is, whatever sentimentalists may say, a duty.

Like Wittgenstein - Collingwood surely loathed Russell politically – see 29.92-3

There is one specific matter that intrigues me.  During his transition from philosopher to economist, around 1925, Keynes became obsessed with the mathematics of historical metrology.  It was a passing phase, he later scoffed at the whole matter.  I long wondered if this experience was directly on an anti-scientific path that led him to eventually claim that Isaac Newton had sold his soul to the devil?  Turning now to Wittgenstein, in his later musing he wrote on a number of matters to do with the foundations of metrology – for instance concerning an imaginary tribe who used elastic rulers.  Was this connected to private discussion with Keynes I wonder?  Taken at face value, there is a good argument that such talk is absurd, or perhaps “stupid”.  But perhaps there is another way of reading that material which could just possibly bear on economic matters?

Rob Tye