Early on in the Archeology, Foucault repeatedly mentions the analysis of thresholds as one of the key elements in his method. The term gains more specificity, however, in the second-to-last chapter, ‘Science and Knowledge.’ A threshold, in basic terms, is the point at which a discursive formation is transformed (or transforms itself). Thus, we can speak of the threshold of emergence or of disappearance for a given discourse. In regard to those sub-formations known as sciences, we can identify a series of specific thresholds: positivity, epistemologization, scientificity, and formalization (see section fourteen). Foucault notes that archeological analysis describes the transformations of scientific discourse primarily in terms of the threshold of epistemologization (that is, at the level at which a discursive positivity takes the position of knowledge). Crucially, thresholds are not absolutely tied down to chronology; a threshold is not necessarily a single point in time. Neither is the threshold at which a discourse changes necessarily the threshold for the transformation of its statements, objects, concepts, strategies, or subject- positions. And neither is the series of thresholds for scientific discourses a regular one: thresholds may occur out of sequence, or all at once, and some may not occur at all.
