Philosopher and Historian of Thought
Foucault, like many began his philosophical career considering psychological phenomena. In Mental Illness and Personality(1954), he developed an existential phenomenology within the boundaries of Marxist thought.
His interest in philosophical science and history led him to write extensively on the middle ages and the "archaelogy of knowledge." Shifting to a more geneological explanation of the transitions between major stages of human development led him to consider the causal effects of non-related causes upon the development of new thought.
His major works also include: History of Madness in the Classical Age(1961), The Birth of the Clinic(1963), The Order of Things(1966), and The Archaeology of Knowledge(1969). His later works dealing with sexuality and religion, as well as modern thought include Discipline and Punish(1975), History of Sexuality(1976), The Confessions of the Flesh(unpublished), The Use of Pleasure(1984), and The Care of the Self(1984).
His later works clearly show the major thrust of his thought: he sought the liberation of man from contingent conceptual constraints masked as unsurpassable a priori limits and the adumbration of alternative forms of existence.