I recall a short but striking conversation with the formidable Piero Sraffa at the Economics Faculty cocktail party after Dennis Robertson’s Marshall Lectures. I well knew that it was Sraffa whom Wittgenstein had described as his mentor during the gestation of the Philosophical Investigations, but I still ventured a rather simple-minded remark about the obvious importance of the fact-value distinction to the social sciences. He turned on me his charming smile and glittering eyes. Did I really suppose that one could switch from fact to value as if simply moving a handle? His voice rose and his Italian accent grew sharper. “Fact, value! Value, fact! Fact, value! Value, Fact! FACT, VALUE! VALUE, FACT!” I beat a swift and chastened retreat. — W.G. Runciman, Confessions of a Reluctant Theorist, 18.