Why are compatibilists also called soft determinists?

Compatibilists are referred to as "soft determinists" because they maintain that free will and determinism are logically consistent, unlike "hard" determinists who argue that the truth of determinism necessitates the nonexistence of free will.12

The term "soft" reflects the approach these philosophers take to reconcile the two concepts. Rather than rejecting the deterministic view that human actions are causally inevitable, they typically attempt to achieve reconciliation by subtly revising or weakening the commonsense, intuitive notion of free will. For example, some soft determinists define acting freely as simply acting in accordance with one's own desires or identifying with one's own motivations, even if those desires are themselves determined by prior events. By redefining free will in this way, they argue that individuals can be held morally responsible for their actions within a deterministic framework, without requiring the "impossible" or robust version of freedom demanded by some critics.23