Free will and determinism


Determinism is when one’s behaviour is thought to be influenced by internal or external forces.  Internal would be things like hormones and external forces would include the way you were brought up by your parents.

Free will means that one can make most decisions.

If we accept a deterministic account of psychology then we can accurately predict human behaviour, which brings psychology into the same realms of science as physics or chemistry.  Without a deterministic approach many may not consider psychology as a science.   However in the twentieth century science had been found to be less deterministic than previously thought.  For example, it is not possible to measure the position and velocity of a subatomic particle at the same time (Heisenberg’s uncertainty principle 1927). Small changes can lead to large changes; the flap of a butterfly’s wings could ultimately lead to a complete change in the weather system (‘the butterfly effect’ in Chaos theory, Hilborn 1994).


The behaviourists believe that our environment determines most of our behaviours.  We repeat behaviour that is rewarded, and we do not repeat behaviour that is not rewarded.

Freud was also a believer in determinism.  He argued that trivial phenomena such as missing an appointment calling somebody by the wrong name or humming a particular tune had definite causes within the individuals motivational system.

William James proposed the idea of soft determinism.  He found that there was a need to distinguish between behaviours that are highly constrained by the situation and behaviours that are modestly constrained by the situation.  For example a young boy may be made to apologise for swearing or risk punishment (highly constrained behaviour) or the boy may feel genuinely upset at causing an offence and therefore give an apology (modestly constrained behaviour). 

It is difficult to test whether determinism is the correct approach because we only have a very limited knowledge of the internal and external forces that might be influencing an individual’s behaviour.

Physiological determinism refers to the biological approach, which in the main is deterministic.  Clearly physiological factors provide explanations of behaviour but may not offer a complete explanation.  Research on nonhuman animals supports the physiological deterministic point of view but as humans are far more complex this approach may not be so applicable in explaining human behaviour.

Environmental determinism refers to the behaviourist approach whereby much of our behaviour is thought to be influenced by external (environmental) factors.  The cognitive approach is mechanistic and therefore also deterministic.

Psychic determinism refers to the psychoanalytic approach, which suggests that adult behaviour, or personality is predetermined by events in early childhood.  Freud believed that the actual causes of our behaviour are unconscious and therefore hidden.  Psychoanalysis is based on principle that people can change so therefore there must be a certain amount of free will.  Freud warned against “over determination” warning that behaviour has multiple causes some of which are conscious and therefore can be subject to free will.

Genetic determinism with refers to the evolutionary approach.  Physical and psychological characteristics are inherited and such characteristics can be naturally selected and passed onto the next generation.  Such a viewpoint probably better accounts for the behaviour of animals further down the evolutionary scale; cultural evolution could have a greater effect on human behaviour.

On the other hand the humanistic approach embraces freewill.  Carl Rogers believes that humans have an innate drive towards positive growth and self-actualisation.  It is up to the individual to “own” his or her own behaviour; Rather than saying a particular behaviour is not like them (for example when following the crowd) individuals should strive to be themselves and take responsibility for their own actions.  Rogers proposes client centred therapy in which the therapist is called a “facilitator” whose role it is to make it easier for the patient to exercise free will.  Humanistic psychologists argue that regarding human behaviour as being influenced by external forces is dehumanising.

A problem for free will is causality.  Free will would suggest that nothing causes an action.  But anyone displaying only random behaviour would be classified as mentally ill or very stupid.  Free will needs to explain what causes actions to take place otherwise behaviours are seen as being determined.


It may not make much sense to talk about “free will” as it doesn’t really offer an explanation as the philosopher John Locke (1632 to 1704) said, “we may as properly say that the singing faculties sings and the dancing faculty dances as that the will chooses.”

We can never devise an experiment to decide whether or not free will influences human behaviour.

Internal factors (such as character or personality) are the results of causal sequences stretching back into the past.  The argument thus becomes, could a solitary internal factor such as free will be immune from the influence of the past.

Free will and determinism may not be incompatible.  If free will is seen as conscious thinking and decision-making then this can explain how behaviours are determined yet are subject to free will as well.  It is perhaps wrong to consider free will as an intruder forcing its way into the sequences of physical events taking place within the brain.




Michael W.Eysenck & Cara Flanagan, 2001, Psychology for A2 level, Psychology Press, ISBN 1-84169-251-4 (Highly recommended text for broad overview of psychology, written in an easy to understand style)