Ideologies can be thought to be sometimes perceived as being an "unified" body of historical information. A sort of body that reflects how an individual or a group will come to perceive the current state of things as well as future things.
However, since there definitely exists multiple strains of thought and not just one, then how is it possible to perceive things as coming from "one strain of thought" or claim that "just this one strain/thought exists (as a dominant one over others)"?
For example, if one bases political views on John Rawls' Social Contract theory for example, then why would this "necessarily" be a dominant view over some other views? Like what defines whether some idea is a "fixed" feature of the history (something that cannot be "erased" in the culture you're in) or whether it can be varied (e.g. you can replace Social Contract theory with some other idea).
Is the "choice" of what strain to use for solidifying one's worldview still freely choosable or are there some concepts that everyone in a culture must abide to (e.g. some political theories have relied on "divine rights").