He married his first wife, Renée Ayer (née Lees), the former wife of the philosopher A. J. Ayer, in 1961.[1][2] They had a daughter by this marriage which ended with Renée's death in 1980.[8] In 1985 he married Nancy Cartwright, who was then his colleague at Stanford[9][2] and is now Professor of Philosophy at Durham University and at the University of California, San Diego. The couple had two daughters.[8]