Determinism

Determinism is the metaphysical idea that everything that happens in the universe can only happen one way. Throughout the history of philosophy, deterministic theories have emerged from various, sometimes overlapping, motivations. Like eternalism, determinism is concerned with specific events rather than the future as an abstract concept. It is frequently contrasted with free will, though some philosophers believe the two can coexist. The opposite of determinism is indeterminism, which holds that events are not caused in a deterministic fashion.

Historically, debates about determinism have produced many philosophical positions and several distinct varieties. One key debate concerns the scope of what is determined. Some philosophers argue that the entire universe is a single determined system, while others point to more limited determined systems. Another common debate is whether determinism and free will can both be true; compatibilism and incompatibilism are the opposing sides of this argument.

Determinism should not be confused with the self-determination of human actions by reasons, motives, or desires. Instead, it deals with interactions that affect cognitive processes in people’s lives, focusing on cause and effect in human actions. In cognitive processes, cause and result are always linked. The view assumes that if an observer had enough information about an object or person, they could predict every subsequent move of that object or person. However, determinism rarely requires that perfect prediction be practically possible.

Causal determinism holds that every event results from prior events and natural laws, while nomological determinism emphasizes that the future can be predicted from past and present states. Necessitarianism claims that only one possible world exists, and predeterminism suggests events are fixed in advance, sometimes biologically or genetically. Fatalism and theological determinism attribute outcomes to fate or divine omniscience, whereas adequate determinism and interpretations of quantum mechanics explore probabilistic or emergent constraints on large-scale phenomena. Philosophical varieties extend to human behavior, including biological, psychological, social, and cultural determinism, as well as structural determinism, which focuses on systemic constraints. Historically, determinism appears in both Western traditions—from the Presocratics and Stoics to Newtonian mechanics—and Eastern philosophy, including karma, Ājīvika fatalism, and Buddhist dependent origination. Modern science recognizes deterministic models in classical physics and complex generative processes, while quantum mechanics introduces probabilistic and debated interpretations.

**Varieties**

Determinism may commonly refer to any of the following viewpoints:

**Causal** Causal determinism, sometimes synonymous with historical determinism (a kind of path dependence), is the idea that every event is necessitated by prior events and conditions together with the laws of nature. However, it is broad enough to consider that one’s deliberations, choices, and actions are often necessary links in the causal chain that brings something about. In other words, even though our deliberations, choices, and actions are themselves determined like everything else, it is still the case, according to causal determinism, that the occurrence of other things depends on our deliberating, choosing, and acting in a certain way. Causal determinism proposes an unbroken chain of prior occurrences stretching back to the origin of the universe. The relation between events and that origin may not be specified. Causal determinists believe nothing in the universe has no cause or is self-caused. More generally, it is the idea that everything that happens and exists is caused by antecedent conditions. In nomological determinism, these conditions are considered events, implying the future is completely determined by prior states of the universe and the laws of nature. These conditions can also be metaphysical in origin, as in theological determinism.

**Nomological** Nomological determinism is the most common form of causal determinism and is generally synonymous with physical determinism. It is the notion that the past and present dictate the future entirely and necessarily by rigid natural laws, and that every occurrence inevitably results from prior events. Nomological determinism is sometimes illustrated by Laplace’s demon, an omniscient observer who, knowing with infinite precision all positions and velocities of every particle, could predict the future entirely. Ernest Nagel viewed determinism in terms of a physical state, declaring a theory deterministic if it predicts a state at other times uniquely from values at one given time.

**Necessitarianism** Necessitarianism is a metaphysical principle that denies all mere possibility and maintains there is only one possible way for the world to exist. Leucippus claimed there are no uncaused events and that everything occurs for a reason and by necessity.

**Predeterminism** Predeterminism is the idea that all events are determined in advance. The concept is often argued by invoking causal determinism, implying an unbroken chain of prior occurrences stretching back to the origin of the universe. In the case of predeterminism, this chain has been pre-established, and human actions cannot interfere with its outcomes. Predeterminism can be categorized as a specific type of determinism when used to mean pre-established causal determinism.