John Dewey (1859-1952) was born the year Charles Darwin published the ground-breaking book Origin of Species. Born at the dawn of the great evolutionary debate that has capped off the long-standing conflict of Religion and Science, it is no surprise that a philosophically-minded man such as Dewey would be influenced by the debate--and have his own insightful input.
Dewey started his career as a Christian but over his long lifetime moved towards agnosticism. His philosphical writings start out apologetic; over his life he gradually lost interest in formal religion and focused more on democratic ideals. Moreover, he became very devoted to applying the scientific method of inquiry to both democracy and education.
Dewey is grouped with Pierce and William James as founders of Pragmatism. Pragmatism has never been concretely defined, but at its core is a philosophical view of human knowledge and thought as being biological in nature; in modern psychological terms, it is equivalent to the gestalt or paradigm theory of knowledge--namely that our knowledge is meaningful in perspective to its relationship to us. Taken to an extreme, it could imply that there is no objectivity to knowledge.
While many have criticized pragmatism (and Dewey's opinion), it is obvious from a study of Dewey's writings that he did not deny objective truth. Dewey's efforts at defining pragmatism were essentially an effort to reconcile the fallibility of human perspective in relation to objective reality. It's doubtful that Dewey (or any other philosopher) succeeded in this debate.
Perhaps the most lasting effect of Dewey's career was his impression on educational philosophy. Dewey was part of the Progressive movement in education; he pushed for experimental approaches in the classroom.
Over the years since Dewey's death, Dewey's philosophy of education has been criticized as being a source of institutional problems. Some groups felt that Dewey helped foster the attitudes towards education that led to the breakdowns in classrooms starting in the 1960s. While the criticisms have remained through the decades, it is unlikely that the breakdown in classroom structure is the fault of Dewey: Dewey's writing may talk about freedom for students, but it is also just as full of passage admonishing teachers to "direct" and "steer" students in the proper directions. Critics have read into Dewey's writing a lack of structure; they have failed to see that Dewey's conception of education was full of structure--namely the structure of the scientific method.