a native of Miletus, was a distinguished philosopher of the Megarian school. The principal events in his personal history are quite unknown. Indirect evidence shows that he was a younger contemporary of Aristotle, whose philosophy he attacked with great bitterness, and that he numbered Demosthenes among his pupils for a while. He is not known to have written any independent work, and his name has been preserved chiefly on account of some celebrated though false and captious syllogisms of which he was the reputed author.