As a modern philosophical field, phenomenology investigates the organization of conscious experience, dealing with questions, for instance, of how the division between subject (ego) and object (world) arises and how things in the world are classified. Since much historical research concerns the historical actor’s consciousness (and self-consciousness), some historians have naturally turned to phenomenological methods to assist them.
Phenomenologists assume that the consciousness is not formed by chance and is structured by something other than itself. Also, in everyday life, persons have no critical control over structured consciousness. Edmund Husserl, the German philosopher who originated phenomenology, conceived of his philosophy as a strategy for “saving” consciousness (and the world of meaning and values as lived in ordinary life) from the reductivist theories of 19th century mechanistic science, such as that of Freud.
As structured, consciousness creates the “world” each person experiences. Phenomenological analysis seeks to describe the features of this “world,” such as what is included in it, what is not, and by what order objects and events are related. The organizational rules of the “real world” can include, for instance, mechanical causality, magical juxtaposition, and psychological over-determination. These rules are not actually independent features of an “objective world,” according to phenomenologists, but are structures of meaning and values in our consciousness which we experience as if they were independent of us. (Phenomenology opposes the English tradition of empiricism.) Since classification of objects involves such organizational rules and is intellectually fundamental to scientific theory, phenomenology is potentially useful to critical scholarship in the history of science.
“Pure phenomenology” only describes each person’s world, but most scholars are interested in the sources of the nonconscious structure that organizes consciousness. Schools of phenomenological theory divide primarily over the issue of the extent to which language is given a major role in structuring experience. Freud considered the libido to be the basic causal agency in developmental phenomenology. He conceived of the libido as a biological, non-linguistic force related to the reproductive drive as described by Darwin. French and German humanistic phenomenologists, in contrast to Freud, ascribe a greater role to language in structuring consciousness. Michel Foucault, the most important French phenomenologist in the school of Gaston Bachelard and Georges Canquilhem, for instance, influenced historians of science with his work on the “order of things” (meaning here scientists’ taxonomical classification of objects of study). Foucault stated directly that “biology … must not be regarded as the first human [science], or the most fundamental.”[ Foucault, The Order of Things, 351.] According to Foucault, language constructs the reality which sciences describe. Language itself is a structure of rules and norms that result from mankind’s need to work to survive. In Foucault’s view, sciences do not describe an “objective” empirical reality, but represent “reality” in a way that, unconsciously to the scientist, fulfill human needs.
Gaston Bachelard, La formation de l’ésprit scientifique; contribution a une psychanalyse de la connaissance objective ( Paris: Vrin, 1938);
Canguilhem, Georges, Ideology and rationality in the history of the life science. Translated by Arthur Goldhammer (Cambridge : MIT Press, 1988);
Michel Foucault, The Order of Things: An Archaeology of the Human Sciences, A translation of Les Mots et les choses  (New York: Pantheon Books, 1970);
Gary Gutting, ed. The Cambridge Companion to Foucault. Cambridge ([England]/ New York: Cambridge University Press, 1994);
Gary Gutting, Michel Foucault’s Archaeology of Scientific Reason (New York: Cambridge University Press, 1989);
Charles Harvey, W. Husserl’s Phenomenology and the Foundations of Natural Science (Athens, Ohio: Ohio University Press, 1989);
Dominique Lecourt, L’Epistemologie historique de Gaston BachelardBachelard, G.. 5e ed. (Paris: J. Vrin, 1978);
Mary Tiles, Bachelard,Bachelard, G. Science and Objectivity (Cambridge/ New York: Cambridge University Press, 1984).