determinism, philosophical thesis that every event is the inevitable result of antecedent causes. Applied to ethics and psychology, determinism usually involves a denial of free will, although many philosophers have attempted to reconcile the two concepts. Thomas Hobbes, identifying the will with appetites and defining freedom as the absence of impediments, concluded that free will exists where nothing prevents a person from satisfying his prevailing appetite. David Hume argued that a person's willful conduct counts as freely chosen even though his will has itself been determined by his motives. William James called such attempts to fit notions of free will into determinist systems "soft" determinism; "hard" determinism excludes the possibility of free will altogether. The doctrine of determinism is opposed by the principle of emergence, which states that truly novel and unpredictable events may occur out of the composite forces of nature.