Witnesses disagree, but the most neutral account is that there was a meeting of the Moral Sciences Club in Room H3 at Kings College, Cambridge, on October 25, 1946. Bertrand Russell (1872–1970) presided, and Karl Popper (1902–1994) came to give a critical paper on Ludwig Wittgenstein’s (1889–1951) language game theory of truth and how to do philosophy. For one thing, Popper thought that there were moral rules.

At some point, Wittgenstein picked up a poker from the fireplace. He either did this to make a point or out of anger; stories differ. When Wittgenstein asked Popper what the example of a moral rule was, Popper is said to have replied, “Not to threaten visiting lecturers with pokers.” Bertrand Russell, who was by then alienated from Wittgenstein, may or may not have interceded and told them to calm down.

A very entertaining book has been written about this episode and the lives and times of Popper and Wittgenstein by British Broadcasting Corporation journalists David Edmonds and John Eidinow: Wittgenstein’s Poker (2001).