Determinism

Hard and Soft Determinism

Determinism is the philosophical position that all events — including all human behaviour, thought, and emotion — are the inevitable consequences of prior causes operating according to natural laws. Psychological approaches differ in how fully they embrace determinism and in where they locate the determining causes of behaviour. Understanding these positions is central to evaluating psychology's scientific status and its practical implications for moral and legal reasoning.

Hard Determinism

Hard determinism holds that all behaviour is entirely and inevitably caused by prior factors — there are no exceptions, and genuine free will is an illusion. Given complete knowledge of prior states, every subsequent thought and action is in principle fully predictable. Hard determinism is consistent with — and indeed required by — the scientific ideal: science seeks causal laws that predict and explain phenomena. If human behaviour were genuinely uncaused, it would be inexplicable and unpredictable by any scientific method.

Behaviourism represents the clearest case of hard determinism in psychology. Watson and Skinner argued that behaviour is fully determined by conditioning history and current environmental contingencies — the person's thoughts, feelings, and apparent choices are either irrelevant (Watson's radical behaviourism) or themselves conditioned responses.

Biological Determinism

Biological determinism locates determining causes in biology — genetic makeup, neurochemistry, brain structure, and evolutionary history. The biological approach to psychology is explicitly determinist: disorders such as schizophrenia, depression, and OCD are explained in terms of genetic vulnerability and neurochemical dysfunction. Research on the heritability of intelligence, personality, and psychopathology provides empirical evidence for biological causal influence.

The legal and ethical implications of biological determinism are significant. If criminal behaviour is determined by genetic or neurological factors, the traditional basis for punishment — that the offender could have chosen otherwise — is problematised. Research on the MAOA gene variant and neuroimaging evidence of prefrontal cortex abnormalities in violent offenders has been cited in legal defences — raising the question of whether biological determination diminishes or eliminates culpability.

Environmental Determinism

Environmental (situational) determinism holds that behaviour is determined by learning history and current environmental contingencies. Behaviourism exemplifies this: Watson's claim that he could shape any healthy infant into any type of specialist — regardless of biological endowment — is an assertion of pure environmental determinism. Social learning theory, whilst incorporating cognitive mediators, also emphasises the determining role of observational learning, reinforcement history, and environmental modelling.

Psychic Determinism

Psychic determinism, associated with Freud, holds that behaviour is determined by unconscious forces — repressed wishes, unresolved conflicts, and instinctual drives operating below conscious awareness. Apparent choices are not free but reveal the operation of unconscious determinants. Parapraxes (Freudian slips) are not random accidents but determined expressions of unconscious material. This presents itself as scientific — the unconscious operates according to discoverable laws — whilst simultaneously undermining the conscious agency common sense attributes to people.

Soft Determinism (Compatibilism)

Soft determinism, also called compatibilism, attempts to reconcile determinism with a meaningful concept of freedom. It accepts that behaviour is causally determined but argues this is compatible with free will — defined not as being uncaused, but as acting in accordance with one's own desires, values, and reasoning rather than from external compulsion. William James argued that humans are deterministic systems whose internal states (desires, beliefs, reasoning) are themselves part of the causal chain — so that self-directed action is not illusory but reflects genuine internal causation.

Many psychological approaches implicitly adopt soft determinism. The cognitive approach treats people as agents who apply reasoning to their situations, whilst acknowledging that both the situations and the reasoning processes have causal histories. Cognitive-behavioural therapy assumes that unhelpful thought patterns were causally determined by prior experience, yet retains the presupposition that clients can identify, evaluate, and change these patterns — a form of self-directed causal change that presupposes some degree of agency.