John Dewey (; October 20, 1859 – June 1, 1952) was an American philosopher, psychologist, and educational reformer whose ideas have been influential in education and social reform. He was one of the most prominent American scholars in the first half of the twentieth century.

The overriding theme of Dewey's works was his profound belief in democracy, be it in politics, education, or communication and journalism. As Dewey himself stated in 1888, while still at the University of Michigan, "Democracy and the one, ultimate, ethical ideal of humanity are to my mind synonymous." Dewey considered two fundamental elements—schools and civil society—to be major topics needing attention and reconstruction to encourage experimental intelligence and plurality. He asserted that complete democracy was to be obtained not just by extending voting rights but also by ensuring that there exists a fully formed public opinion, accomplished by communication among citizens, experts and politicians, with the latter being accountable for the policies they adopt.

Dewey was one of the primary figures associated with the philosophy of pragmatism and is considered one of the fathers of functional psychology. His paper "The Reflex Arc Concept in Psychology," published in 1896, is regarded as the first major work in the (Chicago) functionalist school of psychology. A Review of General Psychology survey, published in 2002, ranked Dewey as the 93rd-most-cited psychologist of the 20th century.

Dewey was also a major educational reformer for the 20th century. A well-known public intellectual, he was a major voice of progressive education and liberalism. While a professor at the University of Chicago, he founded the University of Chicago Laboratory Schools, where he was able to apply and test his progressive ideas on pedagogical method. Although Dewey is known best for his publications about education, he also wrote about many other topics, including epistemology, metaphysics, aesthetics, art, logic, social theory, and ethics.