Mortimer Jerome Adler (December 28, 1902 – June 28, 2001) was an American philosopher, educator, encyclopedist, and popular author. As a philosopher he worked within the Aristotelian and Thomistic traditions. He taught at Columbia University and the University of Chicago, served as chairman of the Encyclopædia Britannica board of editors, and founded the Institute for Philosophical Research.
He lived for long stretches in New York City, Chicago, San Francisco, and San Mateo, California.
While doing newspaper work and taking night classes during his adolescence, Adler encountered works of men he would come to call heroes: Plato, Aristotle, Thomas Aquinas, John Locke, John Stuart Mill, and others, who "were assailed as irrelevant by student activists in the 1960s and subjected to 'politically correct' attack in later decades." His thought evolved toward the correction of what he considered "philosophical mistakes", as reflected in his 1985 book Ten Philosophical Mistakes: Basic Errors in Modern Thought. In Adler's view, these errors were introduced by Descartes on the continent and by Thomas Hobbes and David Hume in Britain, and were caused by a "culpable ignorance" about Aristotle by those who rejected the conclusions of dogmatic philosophy without acknowledging its sound classical premises. These modern errors were compounded and perpetuated by Kant and the idealists and existentialists on the one side, and by John Stuart Mill, Jeremy Bentham, and Bertrand Russell and the English analytic tradition on the other, according to Adler. He corrected these mistakes, at least to his own satisfaction, with reference to insights and distinctions drawn from the Aristotelian tradition.
Adler was born in Manhattan, New York City, on December 28, 1902, to Jewish immigrants from Germany: Clarissa (Manheim), a schoolteacher, and Ignatz Adler, a jewelry salesman. He dropped out of school at age 14 to become a copy boy for the New York Sun, with the ultimate aspiration of becoming a journalist.