Absolutism

Etymology

From Latin "absolutus" ("freed, unrestricted"), from "absolvere" ("to loosen from"), plus "-ism." It named the doctrine of unlimited monarchy in the 18th and 19th centuries, then broadened to any belief in unconditional principles — moral absolutism, for instance.

noun · /AB-suh-loo-tiz-um/
The principle that some rule, value, or authority is total and admits no exceptions or limits.
What it names
Names both a style of government (unchecked, total power) and a cast of mind (no compromise, no shades of gray).
Example
His moral absolutism left no room for the messy trade-offs the situation actually demanded.
Related idea
Relativism is its opposite pole — the view that truth or morality depends on context; absolutism insists some things hold everywhere, always.