Scientific psychiatry?

Dr Turner is quite wrong to argue that Donald Davidson has shown there ‘cannot, in any useful sense, be a science of the mental because of the impossibility of either strict psychological or strict psychophysical laws’ (Turner, 2003: p. 472). It is true that Davidson (1970) argued that there could not be strict laws relating mental events either to physical events or to each other, but its lack of strict laws does not endanger the scientific status of psychiatry, since strict laws are rare in science.

Davidson argues that the relationship between a cause and an effect is strictly lawful if and only if the cause is always followed by the effect irrespective of what else is going on; a sentence stating that the cause occurred must logically entail a sentence asserting the existence of the effect. Davidson (1993: pp. 8–9) concedes that this very demanding conception of a law is ‘something that one could at best hope to find in a developed physics’ and that ‘there are not, and perhaps could not be expected to be, laws of this sort in the special sciences. Most, if not all, of the practical knowledge that we (or engineers, chemists, geneticists and geologists) have that allows us to predict and explain ordinary happenings does not involve strict laws’.

In ‘the special sciences’ (by which philosophers mean ‘all the sciences except physics’) laws hold only under normal circumstances; unlike strict laws, they may fail to hold if circumstances are sufficiently abnormal. Davidson's view is quite consistent with the existence of laws in psychiatry that are not strict but are as robust and useful as laws in genetics, chemistry or geology. Unless one thinks that chemistry, genetics and geology are useless, this means that there could be laws robust enough to make psychiatry a useful science of the mind. If psychiatry counts as a science in the same sense as genetics counts as a science, even the most fervent proponents of scientific psychiatry should be satisfied.