Michel Foucault (1926–1984) was a major figure in two successive waves of 20th century French thought--the structuralist wave of the 1960s and then the poststructuralist wave. By the premature end of his life, Foucault had some claim to be the most prominent living intellectual in France.
Foucault’s work is transdisciplinary in nature, ranging across the concerns of the disciplines of history, sociology, psychology, and philosophy. At the first decade of the 21st century, Foucault is the author most frequently cited in the humanities in general. In the field of philosophy this is not so, despite philosophy being the primary discipline in which he was educated, and with which he ultimately identified. This relative neglect is because Foucault’s conception of philosophy, in which the study of truth is inseparable from the study of history, is thoroughly at odds with the prevailing conception of what philosophy is.
Foucault’s work can generally be characterized as philosophically oriented historical research; towards the end of his life, Foucault insisted that all his work was part of a single project of historically investigating the production of truth. What Foucault did across his major works was to attempt to produce an historical account of the formation of ideas, including philosophical ideas. Such an attempt was neither a simple progressive view of the history, seeing it as inexorably leading to our present understanding, nor a thoroughgoing historicism that insists on understanding ideas only by the immanent standards of the time. Rather, Foucault continually sought for a way of understanding the ideas that shape our present not only in terms of the historical function these ideas played, but also by tracing the changes in their function through history. (from Internet Encyclopedia of Philosophy). For more, please visit: http://www.iep.utm.edu/foucault/