His interest in knowledge has contributed to and supported the concept of rhetoric as epistemic. His description of the utterance parallels in many respects the notion of speech act. Also, his conception of power broadens the rhetorical view of power as discourse which accomplishes certain intended effects or as a particular rhetor's personal power or credibility in a situation. Therefore, as periods in history change, so does a society's existing knowledge structures. Knowledge is inextricably bound to the discourse of a certain period.
Discursive formations organize knowledge and in addition are inseparable from knowledge.
They determine the kinds of communicative practices societies will engage in. Therefore, they allow some forms of discourse while they prohibit other forms. Discursive formations are subject to rules. Speakers express their knowledge through the articulation of utterances that conform to a specific set of rules. Statements and evidence to the contrary were generally denied and silenced.