Holism and reductionism: levels of explanation in Psychology. Biological…

The idea

Reductionism explains behaviour by breaking it into its simplest parts, justified by parsimony; holism insists some things exist only in the whole, which is what Gestalt psychologists meant by the whole being more than the sum of its parts. Between the two sit levels of explanation. Obsessive-compulsive disorder can be described socio-culturally as deviating from cleanliness norms, physically as repetitive hand-washing, psychologically as an intrusive thought, physiologically as an overactive worry circuit and neurochemically as low serotonin. Biological reductionism works at the lowest level, which is why drug treatment targets serotonin. Environmental reductionism, the behaviourists' version, breaks learning down into stimulus-response links built by conditioning, as Skinner did with rats in a box.

What earns the marks

• Holism: behaviour must be studied as a whole system because analysing it into parts destroys the thing being explained (Gestalt psychology; the humanistic approach).
• Reductionism: analysing behaviour into its constituent components, defended by parsimony, the preference for the simplest explanation that works.
• Levels of explanation: socio-cultural, psychological, physical, physiological and neurochemical accounts of the same behaviour, ordered from most to least holistic.
• A worked example is expected: obsessive-compulsive disorder as deviating from social norms, as hand-washing, as an intrusive thought, as an overactive neural circuit, as low serotonin.
• Biological reductionism: behaviour explained by genes, neurochemistry and brain structure, the level at which drug therapies act.
• Environmental or stimulus-response reductionism: behaviourists reduce complex learning to chains of association formed by classical and operant conditioning.
• AO3: reductionist accounts operationalise cleanly and support controlled experiments, which is where the scientific credibility comes from.
• AO3: they can also strip out meaning, because describing the neurochemistry of a behaviour does not explain what the behaviour was for.
• AO3: holism resists testing and offers no way to choose between competing causes, which is why humanistic psychology has produced little hard evidence.

Common mistakes and how to put them right

• Using 'reductionist' as an insult rather than a description.

  Put it right: Reduction is often exactly why a line of research produced usable treatment.

• Listing the levels of explanation without running one behaviour through them, which forfeits the example credit the question is built around.

• Confusing environmental reductionism with the nurture side of nature-nurture.

  Put it right: It is a claim about the size of the unit of analysis, not about where behaviour originates.

• Calling the biological approach holistic because it refers to the whole brain.

  Put it right: The level of explanation is what decides this, not the size of the organ.

Exam tips

• Name your behaviour in the first sentence and use the same one at every level; this structure helps to clearly demonstrate your knowledge of the different levels of explanation.
• Evaluate by asking what each level can and cannot predict, rather than asserting that one is better than another.
• If asked to discuss with reference to a named approach, evaluate the level that approach works at, not reductionism in the abstract.