Why is the ninth month called September?
1796, "science of ideas," originally "philosophy of the mind which derives knowledge from the senses" (as opposed to metaphysics), from French idéologie "study or science of ideas," coined by French philosopher Destutt de Tracy (1754-1836) from idéo- "of ideas," from Greek idea (see idea) + -logy. Later used in a sense "impractical theorizing" (1813). Meaning "systematic set of ideas, doctrines" first recorded 1909.
Ideology ... is usually taken to mean, a prescriptive doctrine that is not supported by rational argument. [D.D. Raphael, "Problems of Political Philosophy," 1970]
ideology i·de·ol·o·gy (ī'dē-ŏl'ə-jē, ĭd'ē-)
The body of ideas reflecting the social needs and aspirations of an individual, a group, a class, or a culture.