Is there an equivalent word for "discourse" signifying not a way of speaking but a way of thinking?
Two words come to mind:
ideology:
a: a manner or the content of thinking characteristic of an individual, group, or culture.
b: the integrated assertions, theories and aims that constitute a sociopolitical program. (Websters)
and
tenet: a principle, belief, or doctrine generally held to be true especially: one held in common by members of an organization, movement, or profession (Websters)