This paper extends correctness and refinement reasoning methods in order to show how angelic nondeterminism can be systematically transformed into demonic nondeterminism or determinism. This kind of transformation is important because angelic nondeterminism assumes that the choices will be resolved intelligently by an agent interested in establishing the postcondition. When angelic nondeterminism is reduced into demonic nondeterminism or determinism, such intelligent choices are no longer necessary. Reducing angelic nondeterminism is generally not a refinement; however, when context is taken into consideration, it can be a correctness-preserving transformation.