Theodore Sider (generally known as "Ted") is an American philosopher specializing in metaphysics and philosophy of language.Since earning his PhD. from the University of Massachusetts Amherst in 1993, Sider has published three books and forty-seven papers. He has also edited a textbook in metaphysics with John Hawthorne and Dean Zimmerman. Sider has held appointments at the University of Rochester, Syracuse University, Rutgers University, and New York University.