David Malet Armstrong AO, Emeritus Professor of Philosophy at the University of Sydney since 1992 and Challis Professor of Philosophy from 1964 to 1991, died peacefully on May 13. He was born in Melbourne in 1926 and is survived by his wife Jenny Armstrong, and by his former wife Madeleine Haydon. David was a member of the board of directors of Quadrant from 1975 to 2014.   I first met David Armstrong early in 1947 when, recently discharged from the Navy, he arrived at Sydney University and enrolled in Philosophy 1. It was obvious immediately that he was a special…