Scientific evidence and political decisions

Sir, – Michael McDowell makes a very important point which is often forgotten on both sides of the Irish Sea ("What is 'the science' politicians must follow?", Opinion & Analysis, June 12th).

Speaking as a science adviser to governments, I can say that, in complex social issues, science is rarely so complete in its understanding that it can be used to decide a course of action; when it is, decision-making is often handed over to an expert body.

More usually science can help to establish, first, the outer boundaries of practical action (legislation will not be possible to cause rain to fall upwards), and second, the areas of uncertainty within which political decision-making has to take the place of scientific analysis.

Almost by definition, issues that become “political” are those in which gaps in knowledge are wider and the scope for conflicting expert conclusions is greater. In democratic societies, we elect representatives to take the decisions on which there is not a sufficient basis for simple scientific conclusion. I would only differ from Mr McDowell in saying that political risk arbitrage is not a”science”; as Bismarck famously said, it is an art, the art of the possible.

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Identifying what is possible in any given circumstances opens up multiple possibilities for action that may turn out to have been wrongly directed. All governments will make misjudgments when the basis for judgment is incomplete. That is not a reason for the “hurlers on the ditch” to criticise but is a strong reason for a review afterwards, when hindsight can help us identify lessons for the future. – Yours, etc,

Dr MILES PARKER,

( Associate Fellow,

Centre for Science

and Policy,

University of Cambridge),

Fowlmere Royston,

Hertfordshire, UK.