Decadence is a subset of a philosophy of history, not a self-contained theory

Evidence

But “decadence” in that sense and as a theme or ideologeme is not some mere room in the imaginary museum (housing a “culture,” for example, more peculiar than that of the Polynesians); nor is it, as Gilman sometimes thinks, a “theory” that includes presuppositions about psychic and racial health or imbalance; it is a secondary spin-off of a whole theory of history, and a special-case subset of what the Germans call Geschichtsphilosophie. — Fredric Jameson, Postmodernism, or, The Cultural Logic…, 804

Categorization

• DEFINE: Clarifies that ‘decadence’ as a concept only makes sense as a special-case subset of a whole theory of history (Geschichtsphilosophie), not as a standalone theory.