"The Structure of Scientific Revolutions" by Thomas Kuhn

I first read this book, which was published in 1962, when I was studying the History and Philosophy of Science at Cambridge in 1987-8. It was a revolutionary thesis. This is the third edition (1996) which adds a postscript to respond to some of the issues that its original publication raised.

Science, Kuhn suggests, does not make steady progress closer and closer to the truth. Rather, it is oscillates between a 'normal' phase during which scientists solve problems and a 'revolutionary' phase when scientific certainties are thrown out of the window and a radically different understanding is born.

He calls the framework within which normal science is done a 'paradigm' and the revolution a 'paradigm shift'. There are many similarities between the way science develops during a paradigm shift and the way students learn if we assume the 'threshold concepts' theory of learning.

For example, In the 1880s physicists were complacently expecting that soon their classical models would be able to explain all that needed to be explained. They were refining them and making them a little more accurate. There were a few clouds on the horizon. Maxwell's equations suggested that light was an electromagnetic wave but no one could detect the 'aether', the postulated medium through which the e-m waves must ripple. The 'ultra-violet catastrophe' was the theoretical model of the atom which predicted that when you heated something up it should glow purple before it glowed red and at some stage it would radiate infinite amounts of energy in the ultra-violet part of the spectrum. And the photo-electric effect was an experiment which suggested that the energy of the electrons emitted from a surface when light was shone on it was not linked to the brightness of the incoming light. But these were blips and no-one seriously doubted that classical physics would soon be able to solve these problems.

In fact the failure to detect the aether was explained once Einstein had discovered his theory of Special Relativity with its bizarre claims that the speed of light was the fastest possible speed, the simultaneity was relative, that time slowed down as you got faster and that mass and energy were inter-convertible. The ultra-violet catastrophe gave rise to the weird world of Quantum Physics and the photoelectric effect was the key evidence for wave-particle duality which shortly led to de Broglie's claims that particles could behave like waves.

In some ways this makes Science a little like the pile of sand as explained in the book Ubiquity. As grain after grain is added to the pile it becomes more and more unstable. Sometimes there are slight slips; at other times there are near-catastrophic landslides.  Or science is like the punctuated equilibrium model of evolution as described in John Gribbin's brilliant Deep Simplicity. Most of the time evolution just contributes a little variation which make organisms marginally better adapted to their evolutionary niches. But when there is a major ecological catastrophe, evolution goes wild to fill the new ecological niches that have been created.

Kuhn writes with elegance and power. This is a very convincing thesis that had a major impact on the history and the philosophy of Science.

March 2015; 210 pages