决定论（Determinism），又称拉普拉斯信条，是哲学的一种命题，认为每个事件的发生，包括人类的认知、举止、决定和行动都是因为先前的事而有原因地发生。如果从原始宇宙以来，有一连串的事件注定地、从未中断地发生，自由意志则是不可能的。

决定论相信，宇宙完全是由因果定律之结果支配，经过一段时间以后，任何一点都只有一种可能的状态。许多历史性辩论给决定论主题带来了很多变种和哲学立场，最突出地，自由意志辩论卷入了兼容论和不兼容论（compatibilism and incompatibilism）。

决定论不应在原因、动机和欲望或者命定说（Self-determination）（这个学说明确地依赖于上帝存在这一信条）上弄昏人类对活动的决定。

Determinism is the philosophical position that for every event there exist conditions that could cause no other event. "There are many determinisms, depending on what pre-conditions are considered to be determinative of an event or action." Deterministic theories throughout the history of philosophy have sprung from diverse and sometimes overlapping motives and considerations. Some forms of determinism can be empirically tested with ideas from physics and the philosophy of physics. The opposite of determinism is some kind of indeterminism (otherwise called nondeterminism). Determinism is often contrasted with free will.