One of the most striking aspects of Karl Popper's philosophy of science is his insistence that scientific consensus is sleep inducing, intellectually speaking. He did not actually put it quite like that. What he pointed out was that the most successful scientific theory ever devised turned out to be false, even though it had been treated as scientifically practically unquestionable for nigh on two centuries.

Popper was thinking of Newton's theory, whose refutation (as Popper saw it) in 1917 was a key moment in his own intellectual life. Actually there had been those who disagreed with Newton even during the hey-day of Newtonianism (Blake and Goethe, for example). But in their own time they were not taken seriously but what would now be called the scientific establishment, and very probably still aren't. It was not so much that Newton's critics were right, as that Newton himself was not right.

Popper's lesson is little heeded to-day. Critics of the theory of evolution and of the reality of climate change are not so much argued with as vilified, excluded and marginalised in polite scientific and even political circles. It is what one might expect from a very powerful institution, like the medieval Church, but not perhaps from one ostensibly committed to critical rationality and the pursuit of falsification.

The criticisms which are made of the theory of evolution and of climate change, as these things are currently and consensually understood, are not all or entirely without weight. We hope that saying that will not bring a heap of opprobrium on our heads. But even if the criticisms were off the wall, those who take Popper seriously may still occasionally catch a whiff of the falsifying rat behind the painted and perfumed consensus.