... one factor in the public distrust of science has been largely overlooked, and it goes to the heart of the scientific enterprise. The capacity for self-correction is the source of science’s immense strength, but the public is unnerved by the fact that scientific wisdom isn’t immutable. Scientific knowledge changes with great speed and frequency – as it should – yet public opinion drags with reluctance to be modified once established. And the rapid ebb and flow of scientific ‘wisdom’ has left many people feeling jerked around, confused, and increasingly resistant to science itself.

In his hugely influential book, The Structure of Scientific Revolutions (1962), the physicist and philosopher of science Thomas Kuhn argued that ‘normal science’ proceeds within certain reigning ‘paradigms’. In other words, each scientific discipline is governed by an accepted set of theories and metaphysical assumptions, within which normal science operates. Periodically, when this rather humdrum ‘puzzle solving’ leads to results that are inconsistent with the regnant perspective, there follows a disruptive, exciting period of ‘scientific revolution’, after which a new paradigm is instituted and normal science can operate once more....

There is a long list of ideas that were considered ‘scientifically valid’ in their day and have since been discarded. Belief in a flat Earth is a prominent one, along with the Ptolemaic system that had enshrined our planet as the centre of all things celestial. Although it is easy to ridicule that earlier geocentric world view, it was impressively ‘scientific’ in its day, buttressed by elaborate mathematical models and supported by much of the empirical data of the time – albeit based on visual astronomy rather than optical telescopes.

Alchemy is in a real sense the ancestor of what we now call chemistry, but its practitioners had to recant their previous paradigm in order to become, eventually, ‘real’ chemists. Other lost theories include the ‘luminiferous ether’, long believed to constitute a substance that propagates light waves, and whose explanatory reach was later extended to include electromagnetic radiation generally; or ‘caloric’, a hypothetical substance that ostensibly embodied heat energy, and which flowed from hotter bodies to colder ones.

Some of these paradigm shifts occurred before science itself became an institutional endeavour, and did not, therefore, undermine the legitimacy of science as an enterprise. The word ‘scientist’ didn’t even exist until the English historian and philosopher William Whewell coined the term in 1834. Once science became an intellectual discipline and scientists were identified as its practitioners, then along with the good (progress in getting the nature of the natural world right) came the bad (the fact that the wisdom of science wasn’t rock solid)....

Deprived of previous paradigms, many of them comforting, what’s left? Some of these unseated certainties will not be missed, at least not for long: it is relatively straightforward (although not always easy) to keep changing our diets, or to reconfigure our perception of microbes and of the capacity of nerve cells to regenerate and of others to differentiate.

But the loss of any paradigm is disorienting, and to be deprived of many can be downright disheartening....