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Reductionism and Holism


The reductionism / holism debate is a controversy that raises questions about the very nature of “explanation” itself. At first sight such questions can seem difficult and abstract but in essence the two positions in this debate can be summed up in single phrases.

For the reductionist “the simple is the source of the complex”. In other words to explain a complex phenomenon (like human behavior) one needs to “reduce” it to its constituent elements.  For the holist “the whole is more than the sum of the parts”. 

In other words human behavior has its own properties that are not explicable in terms of the properties of the elements from which it is derived. Here we will deal with the reductionist case first.

What is Reductionism?

Reductionism is the belief that human behavior can be explained by breaking it down into smaller component parts.

Reductionists say that the best way to understand why we behave as we do is to look closely at the very simplest parts that make up our systems, and use the simplest explanations to understand how they work.

It is based on the scientific assumption of parsimony - that complex phenomena should be explained by the simplest underlying principles possible. Strong supporters of reductionism believe that behavior and mental processes should be explained within the framework of basic sciences (e.g. physiology, chemistry.... ). 

However any explanation of behavior at its simplest level can be deemed reductionist. The experimental and laboratory approach in various areas of psychology (e.g. Behaviorism, biological, cognitive) reflects a reductionist position. This approach inevitably must reduce a complex behavior to a simple set of variables that offer the possibility of identifying a cause and an effect (i.e. Reductionism is a form of determinism).

Behaviorists such as Skinner explain all behavior as being a result of past learning. T he relationships between stimuli and our responses to them are the basis for all we know and how we behave. This is a reductionist view because complex behavior is being reduced to a simple stimulus and response relationship. 

We might also consider the biological approach to abnormality as reductionist.  The biological approach says that psychological problems can be treated like a disease and so are often treatable with drugs.  Identifying the source of someone’s mental illness as an imbalance of chemicals in the brain is being reductionist.

Reductionism works at different levels. The lowest level of reductionism offers physiological explanation: these attempt to explain behavior in terms of neurochemical, genes and brain structure.  At the highest sociocultural level, explanations focus on the influence on behavior of where and how we live. Between these extremes there are behavioral, cognitive and social explanations.

Supporters of a reductionist approach say that it is scientific. Breaking complicated behaviors down to small parts means that they can be scientifically tested. Then, over time, explanations based on scientific evidence will emerge. However, some would argue that the reductionist view lacks validity.

For instance, we can see how the brain responds to particular musical sounds by viewing it in a scanner, but how you feel when you hear certain pieces of music is not something a scanner can ever reveal.  Just because a part of the brain that is connected with fear is activated while listening to a piece of music does not necessarily mean that you feel afraid. In this case, being reductionist is not a valid way of measuring feelings. 

It is also argued that reductionist approaches do not allow us to identify why behaviors happen.  For example, they can explain that running away from a large dog was made possible by our fear centers causing a stress response to better allow us to run fast, but the same reductionist view cannot say why we were afraid of the dog in the first place.  In effect, by being reductionist we may be asking smaller, more specific questions and therefore not addressing the bigger issue of why we behave as we do.

It has been suggested that the usefulness of reductionist approaches depends on the purpose to which they are put.  For example, investigating brain response to faces might reveal much about how we recognize faces, but this level of description should not perhaps be used to explain human attraction. 

Likewise, whilst we need to understand the biology of mental disorders, we may not fully understand the disorder without taking account of social factors which influence it.  Thus, whilst reductionism is useful, it can lead to incomplete explanations.

Interactionism is an alternative approach to reductionism, focusing on how different levels of analysis interact with one another. It differs from reductionism since an interactionism approach would not try to understand behavior from explanations at one level, but as an interaction between different levels.

So for example, we might better understand a mental disorder such as depression by bringing together explanations from physiological, cognitive and sociocultural levels. Such an approach might usefully explain the success of drug therapies in treating the disorder; why people with depression think differently about themselves and the world; and why depression occurs more frequently in particular populations.

Examples of Reductionism in Psychology

  • Behaviorism assumes that all behavior can be reduced to simple building blocks of S-R (stimulus- response) and that complex behavior is a series of S-R chains.

  • Biopsychology - Explanations for the cause of mental illnesses are often reductionist. Genetics, and neurochemical imbalances are frequently highlighted, as being the main cause of these disorders. In the case of schizophrenia for example excess production of the neurotransmitter dopamine is seen as a possible cause.

    This view clearly has implications for treatment. Gender can also be reduced to biological factors (e.g. hormones). Also, language can be reduced to structures in the brain, e.g. Broca’s area, Wernicke’s area (but holism could state: influence of family, education, social class on language). Another example of biological reductionism is aggression – e.g. testosterone levels.

  • Structuralism – One of the first approaches in psychology. Wundt tried to break conscious experiences down into its constituent (i.e. basic) parts: images, sensations and feelings.

Holistic Psychology

Holism refers to any approach that emphasizes the whole rather than their constituent parts. In other words ‘the whole is greater than the sum of its parts’. Qualitative methods of the humanistic approach reflect a holistic position. Social psychology also takes a holistic view.

A holistic approach therefore suggests that there are different levels of explanation and that at each level there are “emergent properties” that cannot be reduced to the one below.

Reductionist explanations, which might work in some circumstances, are considered inappropriate to the study of human subjectivity because here the emergent property that we have to take account of is that of the “whole person”.  Otherwise it makes no sense to try to understand the meaning of anything that anybody might do.

Examples of Holism in Psychology

  • Humanistic psychology investigates all aspects of the individual as well as the interactions between people.

  • Social Psychology looks at the behavior of individuals in a social context. Group behavior (e.g. conformity, de-individualization) may show characteristics that are greater than the sum of the individuals which comprise it.

  • Psychoanalysis – Freud adopted an interactionist approach, in that he considered that behavior was the results of dynamic interaction between id, ego and superego.

  • Abnormal psychology – mental disorders are often explained by an interaction of biological, psychological and environmental factors. An eclectic approach to therapy is often taken using drugs and psychotherapy.

  • Perception – This is were the brain understands and interprets sensory information. Visual illusions show that humans perceive more than the sum of the sensations on the retina.

Where do the main approaches in psychology stand on reductionism & holism?

The biological approach. Reductionism is often equated with physiological reductionism, offering explanations of behavior in terms of physiological mechanisms. The evolutionary approach uses evolutionary reductionism when reducing behavior to the effects of genes, as in some explanations of altruism or atypical behavior (e.g. depression).

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The behaviorist approach uses a very reductionist vocabulary: stimulus, response, reinforcement, and punishment. These concepts alone are used to explain all behavior. This is called environmental reductionism because it explains behavior in terms of simple environmental factors. Behaviorists reduce the concept of the mind to behavioral components, i.e., stimulus-response links.

The cognitive approach uses the principle of machine reductionism.  Information-processing approaches use the analogy of machine systems, and the simple components of such machines, as a means to describe and explain behavior. More recent computer innovations, such as the Internet and connectionist networks can be described as holist because the network behaves differently from the individual parts that go to make it up. The whole appears to be greater than the sum of its parts. The psychodynamic approach is reductionist in so far as it relies on a basic set of structures that attempt to simplify a very complex picture (e.g. id, ego, superego, unconscious mind). On the other hand, Freud used idiographic techniques (e.g. case study or individual interview) that aim to preserve the richness of human experience rather than teasing out simple strands of behavior.

Humanism emerged as a reaction against those dehumanizing psychological perspectives that attempted to reduce behavior to a set of simple elements. Humanistic, or third force psychologists, feel that holism is the only valid approach to the complete understanding of mind and behavior. They reject reductionism in all its forms.

Their starting point is the self (our sense of personal identity) which they consider as a functioning whole. It is, in the words of Carl Rogers, an “organized, consistent set of perceptions and beliefs about oneself”. It includes an awareness of the person I am and could be. It directs our behavior in all the consciously chosen aspects of our lives and is fundamentally motivated towards achieving self-actualization.

For humanists, then, the self is the most essential and unique quality of human beings. It is what makes us what we are and is the basis of a difference between psychology and all natural science.  Reductionist explanations undermine the indivisible unity of experience. They run counter to and ultimately destroy the very object of psychological enquiry.  A holistic point of view is thus in humanist terms the very basis of all knowledge of the human psyche.

How to cite this article:

McLeod, S. A. (2008). Reductionism and holism. Retrieved from

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