Michael Schrage’s comment on politics and science (September 26) struck a raw nerve: and provoked an extended response from the president of the UK’s Royal Society. Lord Rees advocates that we should base policy on something called “the scientific consensus”, while acknowledging that such consensus may be provisional.

But this proposal blurs the distinction between politics and science that Lord Rees wants to emphasise. Novelist Michael Crichton may have exaggerated when he wrote that “if it’s consensus, it’s not science, if it’s science, it’s not consensus”, but only a bit. Consensus is a political concept, not a scientific one.