In epistemology and the philosophy of science, Bachelard espoused a dialectical rationalism, or dialogue between reason and experience. He rejected the Cartesian conception of scientific truths as immutable; he insisted on experiment as well as mathematics in the development of science. Bachelard described the cooperation between the two as a philosophy of saying no, of being ever ready to revise or abandon the established framework of scientific theory to express the new discoveries. In addition to his contributions to the epistemological foundations of science, Bachelard explored the role of reverie and emotion in the expressions of both science and more imaginative thinking. His psychological explanations of the four elements-earth, air, fire, water-illustrate this almost poetic aspect of his philosophy. -- (Bowker Author Biography)