In philosophy, episteme (Ancient Greek: ἐπιστήμη, romanized: epistēmē, lit. 'science, knowledge'; French: épistémè) is knowledge or understanding. The term epistemology (the branch of philosophy concerning knowledge) is derived from episteme.
See also: Platonic epistemology
Plato, following Xenophanes, contrasts episteme with doxa: common belief or opinion. The term episteme is also distinguished from techne: a craft or applied practice. In the Protagoras, Plato's Socrates notes that nous and episteme are prerequisites for prudence (phronesis).
Aristotle distinguished between five virtues of thought: technê, epistêmê, phronêsis, sophia, and nous, with techne translating as "craft" or "art" and episteme as "knowledge". A full account of epistêmê is given in Posterior Analytics, where Aristotle argues that knowledge of necessary, rather than contingent, truths regarding causation is foundational for episteme. To emphasize the necessity, he uses geometry. Notably, Aristotle uses the notion of cause (aitia) in a broader sense than contemporary thought. For example, understanding how geometrical axioms lead to a theorem about properties of triangles counts as understanding the cause of the proven property of the right triangle. As a result, episteme is a virtue of thought that deals with what cannot be otherwise, while techne and phronesis deal with what is contingent.
For Foucault, an épistémè is the guiding unconsciousness of subjectivity within a given epoch – subjective parameters which form an historical a priori.: xxii He uses the term épistémè (French pronunciation: [epistemɛ]) in his The Order of Things, in a specialized sense to mean the historical, non-temporal, a priori knowledge that grounds truth and discourses, thus representing the condition of their possibility within a particular epoch. In the book, Foucault describes épistémè:: 183
In any given culture and at any given moment, there is always only one épistémè that defines the conditions of possibility of all knowledge, whether expressed in a theory or silently invested in a practice.
In subsequent writings, he makes it clear that several épistémè may co-exist and interact at the same time, being parts of various power-knowledge systems. Foucault attempts to demonstrate the constitutive limits of discourse, and in particular, the rules enabling their productivity; however, Foucault maintains that, though ideology may infiltrate and form science, it need not do so: it must be demonstrated how ideology actually forms the science in question; contradictions and lack of objectivity are not an indicator of ideology. Jean Piaget has compared Foucault's use of épistémè with Thomas Kuhn's notion of a paradigm.
I would define the episteme retrospectively as the strategic apparatus which permits of separating out from among all the statements which are possible those that will be acceptable within, I won't say a scientific theory, but a field of scientificity, and which it is possible to say are true or false. The episteme is the 'apparatus' which makes possible the separation, not of the true from the false, but of what may from what may not be characterised as scientific.
Truth is a thing of this world: it is produced only by virtue of multiple forms of constraint. And it induces regular effects of power. Each society has its regime of truth, its "general politics" of truth: that is, the types of discourse which it accepts and makes function as true; the mechanisms and instances which enable one to distinguish true and false statements, the means by which each is sanctioned; the techniques and procedures accorded value in the acquisition of truth; the status of those who are charged with saying what counts as true.