David Premack (October 26, 1925 – June 11, 2015) was an American psychologist who was a professor of psychology at the University of Pennsylvania. He was educated at the University of Minnesota when logical positivism was in full bloom. The departments of Psychology and Philosophy were closely allied. Herbert Feigl, Wilfred Sellars, and Paul Meehl led the philosophy seminars, while Group Dynamics was led by Leon Festinger and Stanley Schachter.[1]