Bachelard, Gaston (1884—1962) French philosopher of science. Born in Bar-sur-Aube, in the Champagne region of France, Bachelard’s academic career was very slow to start. He spent several years working in a post office before even commencing university study. And it was not until after the First World War, in which he served with distinction (earning the Croix de Guerre), that he finally attained an academic post. His first job was a professor of physics and chemistry at a College in Bar-sur-Aube. He remained there from 1919 until 1930, during which time he began to focus more and more on the philosophy of science. And it was in this area that he eventually made his mark, becoming professor of the philosophy of science at the Sorbonne in 1940. There are two main trajectories in Bachelard’s work, reflecting his conviction that there are two types of thought: scientific and poetic. With respect to science, Bachelard was one of the first thinkers to emphasize discontinuity in the history of thought. Knowledge does not progress according to a logical, linear set of steps moving from partial to complete understanding; rather it progresses unevenly from one misconception to another until understanding is finally attained. On this view, the previous attempts at understanding a particular phenomenon cannot be used as a reliable guide as to how knowledge was attained in the final instance. Bachelard introduced the concept of the epistemological break to characterize the gap between past ignorance and present understanding. This concept was widely influential and was developed further by Canguilhem, Georges (in his account of medical science) and Foucault, Michel (in his histories of the clinic, prison, and madness). It also had enormous impact on Althusser, Louis, who used it to articulate his claim that Marxism broke with both genre and Feuerbach. The other trajectory in Bachelard’s work, reflecting strongly the influence of Jung, Carl, concerns the poetic image, which for Bachelard is not the same thing as a metaphor. It is rather an opening toward the future. In a series of studies on elemental themes---air, water, fire, and space---Bachelard produced a powerful account of the daydream or reverie, arguing that it enables us to get in touch with the deeper reserves of our imagination. The best known of these studies is La Poétique de l’espace (1958) translated as The Poetics of Space (1964), which was a worldwide bestseller. Other books in the series include: La psychanalyse du feu (1938) translated as The Psychoanalysis of Fire (1977); L’Eau et les rêves (1942) translated as Water and Dreams: An Essay on the Imagination of Matter (1994); and La Poétique de la rêverie (1960) translated as The Poetics of Reverie: Childhood, Language, and the Cosmos (1992). Further Reading: D. Lecourt Marxism and Epistemology: Bachelard, Canguilhem and Foucault (1975). M. McAllester Gaston Bachelard: Subversive Humanist (1991). M. Tiles Bachelard: Science and Objectivity (1984).