Michel Foucault, answered from the texts and cited to the page.
The épistème is not a worldview, not the spirit of an age, not a great anonymous legislation that governs what men of a given period can think.1 That suspicion — that I am describing something like a Zeitgeist, a sovereign structure of thought from which no one escapes — is precisely what I want to refuse. What I mean by épistème is more specific and more modest: the totality of relations that can be discovered, for a given period, between the sciences when one analyzes them at the level of discursive regularities.2
It is, in other words, a relational field — not a form of knowledge, not a type of rationality, but the set of connections, gaps, shifts, and articulations that hold between discursive practices and the epistemological figures they give rise to.3 The épistème does not tell you what could be known in a period, as if it were a ceiling on human intelligence; it tells you what, in the positivity of discursive practices, made possible the existence of epistemological figures and sciences at all.4
Two things follow that are often missed. First, the épistème is not static. It is a constantly moving set of articulations and shifts, establishing relations only to give rise to others; it opens an inexhaustible field that can never be closed.5 Second, it is not the only level at which knowledge can be analyzed. One can analyze a body of knowledge as a formation of statements, as a positivity, or as a knowledge in the strict sense — invested in a science, an institution, a legal practice, a fictional narrative.6
The épistème names the relations between these formations at the level of discursive regularities; it does not exhaust what there is to say about any particular science. What the analysis of the épistème questions, then, is not the legitimacy of a science — not "has this discipline earned the right to call itself scientific?" — but the bare fact of its existence: what it is for that science to be a science, and why it appeared when it did rather than earlier or later.7
If comparative grammar could not emerge before Bopp, if anatomo-pathological medicine could not cohere before the early nineteenth century, the explanation lies not in epistemological structure in the abstract, nor in human error or blindness, but in the morphology of knowledge, in the internal disposition of discursive formations.8 And the human sciences — psychology, sociology, anthropology — are part of the modern épistème in exactly the same way that grammar and natural history were part of the classical one.9
That does not make them sciences in the strict sense; it means their positivity is rooted in the epistemological field, that they are not mere ideology or pseudo-scientific fantasy, but that their existence is a historical fact requiring genealogical explanation rather than epistemological vindication.10
By episteme, we mean, in fact, the total set of relations that unite, at a given period, the discursive practices that give rise to epistemological figures, sciences, and possibly formalized systems... The episteme is not a form of knowledge (connaissance) or type of rationality which, crossing the boundaries of the most varied sciences, manifests the sovereign unity of a subject, a spirit, or a period.The Archaeology of Knowledge, p. 199
it is the totality of relations that can be discovered, for a given period, between the sciences when one analyses them at the level of discursive regularities.The Archaeology of Knowledge, p. 199
the total set of relations that unite, at a given period, the discursive practices that give rise to epistemological figures, sciences, and possibly formalized systems; the way in which, in each of these discursive formations, the transitions to epistemologization, scientificity, and formalization are situated and operate.The Archaeology of Knowledge, p. 199
the episteme is not what may be known at a given period, due account taken of inadequate techniques, mental attitudes, or the limitations imposed by tradition; it is what, in the positivity of discursive practices, makes possible the existence of epistemological figures and sciences.The Archaeology of Knowledge, pp. 199–200
the episteme is not a motionless figure that appeared one day with the mission of effacing all that preceded it: it is a constantly moving set of articulations, shifts, and coincidences that are established, only to give rise to others... it opens up an inexhaustible field and can never be closed.The Archaeology of Knowledge, pp. 199–200
It can and must be analyzed both as a formation of statements... as a positivity... as a knowledge (when considering these objects, types of formulation, concepts and opinions as they are invested in a science, a technical recipe, an institution, a fictional narrative, a legal or political practice, and so on).On the Archaeology of the Sciences: Response to the Epistemology Circle, p. 370
the analysis of the episteme is not a way of returning to the critical question ('given the existence of something like a science, what is its legitimacy?'); it is a questioning that accepts the fact of science only in order to ask the question what it is for that science to be a science.The Archaeology of Knowledge, pp. 199–200
if the established fact of intestinal lesions in 'feverous' ailments could not give rise before the beginning of the nineteenth century to an anatomo-pathological medicine, the reason is to be sought neither in the epistemological structure of biology in general... It resides instead in the morphology of knowledge, in the system of positivities, in the internal disposition of discursive formations.On the Archaeology of the Sciences: Response to the Epistemology Circle, p. 370
The 'sciences of man' are part of the modern episteme in the same way as chemistry or medicine or any other such science; or again, in the same way as grammar and natural history were part of the Classical episteme.The Order of Things, An Archaeology of the Human Sciences, pp. 394–395
to say that they are part of the epistemological field means simply that their positivity is rooted in it... they are therefore not merely illusions, pseudo-scientific fantasies motivated at the level of opinions, interests, or beliefs... But that does not necessarily mean that they are sciences.The Order of Things, An Archaeology of the Human Sciences, pp. 394–395