Psychology: Why I class it as a science.

It is sometimes said that Psychology shouldn’t be classed as a science, because psychologists can’t accurately predict what individual people will do:  in a real science, we expect testable predictions.

To be generous, I will allow all  brain-scan linked psychology to be put under neuroscience, and all chemical-linked psychology to be under psychopharmacology.  I will consider only social psychology and the study of individual behaviours.

It is clear that any situation brings out different responses from different human individuals, and that the range of these responses is predictable.

Some situational responses are very common.  In a previous post  I gave some examples of famous response patterns,  but there is a huge range of psychological research into common effects.  (For a quick start, there are many videos and books from Richard Wiseman .)  However, for every standard response there is a sizeable minority who are non-standard.  Does this invalidate the claim to scientific status for psychology?  Consider the reasons for the range of responses:

To begin with, testing of famous effects has made it clear that different cultures prime us to different response sets.  (Laura Spinney’s article on being WEIRD gives a few examples. )

On the individual level, personality and past experience also prime individuals to particular responses.   Research on resilience gives many examples of this.

Finally, for each of us, there is a probability of a particular behaviour in a given situation – even in rats with strongly conditioned responses there is a degree of variability in response.

So, psychologist have found many aspects of variability in response, and are trying to identify causes and measure their effects – alone and in combination – and are testing their predictions.   That sounds like science to me.  However, they still can’t usually predict what an individual will do. So, is that a fatal flaw?

Let us consider Chemistry – that is a science.  Given a set of chemicals, in a given environment, the outputs are predictable – right?  Well, take burning an archetypical carbohydrate:  CH2O (s) + O2 (g)  – >  CO2 (g) + H2O (g).   Can the chemist predict which of the Oxygen gas’s atoms will end in the carbon dioxide?  Consider the history of producing  isocyanides  :  the proportions of different products from a given starting mix was initially hard to predict, and much research was needed before the exact conditions for high yield were found.   With the invention of microwave ovens, chemists found  a new range of conditions for chemical reactions – and again started by finding out the changes in  mixture of products from changes in process.  ( One example is the processing of methane, of interest to the natural gas / syngas industry.)

So, I argue that Psychology can be classed as a science precisely because  (like research Chemists) the researchers accept that there are limits to their knowledge,  that they must measure reality to form ideas of what might be happening (hypotheses),  and that their predictions (from hypotheses) of the results of given processes must be tested against reality before a strong theory can be developed.


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