Sidney Morgenbesser (22 September 1921 – 1 August 2004) was a Jewish American philosopher and professor at Columbia University. He wrote little but is remembered by many for his philosophical witticisms. One of the best known anecdotes has J. L. Austin claiming that, although a double negative often implies a positive meaning (as is the case with "he is not unlike his sister"), there is no language in which a double positive implies a negative.