Over The Horizon

Thomas Kuhn, 1922-1996

A few weeks ago, Thomas Kuhn died, largely unnoticed by the scientific community. Thomas Kuhn? Nuclear physicist, geneticist, chemist, or what? In a way, he was all of that and a good deal more. As one of this century's outstanding historians and philosophers of science, his work centred on the question of just how science actually gathers knowledge, how choices between rivalling theories are made, and how we can understand such major upheavals as the transition from Aristotelian to Newtonian physics, or the transition from Newtonian to quantum mechanics.

Born in 1922 in Cincinnati, US, he studied physics at Harvard and became involved in teaching physics to students of the humanities. As part of the course, he took a closer look at the physics of the ancient Greek philosopher Aristotle, and was stunned by his completely different conception of motion and matter. When confronted with Aristotle, modern scientists are usually quick to point out his mistakes and ridicule him for the navety with which he described the world. Nonetheless, Aristotle's philosophy gave a very coherent and sensible account of nature which in fact determined the principal lines of research for almost 2,000 years. Kuhn asked himself how it could be possible that Aristotle's apparently absurd ideas at one time seemed to make so much sense, and in pursuing an answer to this question he forever changed the way in which we think about the progress of science.

According to Kuhn's theory, most scientific research is done within an accepted framework of basic principles which he called "paradigms". During these normal periods of science, research concentrates on solving "puzzle questions", minor building blocks of theory that fit well within this greater set of explanatory principles. Rather than being challenged by these puzzles, the paradigm defines which questions need answering, and which ones are irrelevant. No set of theories is perfect and there are always areas where the theory does not quite match the data, but usually nobody worries because it is believed that ultimately the paradigm will explain those anomalies too. Yet over time, some researchers may begin to feel troubled by anomalies, and eventually start to doubt the paradigm itself. If enough scientists share these worries, science enters a crisis resolved by a "scientific revolution" in which the old framework of general beliefs is completely overthrown and a new paradigm takes its place. Only then can "normal science" begin again.

When Kuhn's book The Structure of Scientific Revolutions appeared in 1962, it sparked an intellectual firestorm. Kuhn argued that because scientific revolutions involved a change in the very framework under which theories explained nature, there was no strictly logical way of comparing a theory belonging to the old paradigm to one of the successor. Thus he found that at the heart of scientific progress non-rational grounds such as social dynamics and metaphysical beliefs played an important and largely unrecognised role.

We owe it to Thomas Kuhn if today such an idea seems to be almost obviously true, if we recognise the mutual effect science has on society -- and vice versa. Even the most aseptic laboratories can not be kept entirely clear of his original idea of paradigms as the non-negotiable cornerstones of daily research. We live in the era after Thomas Kuhn.

Andy Reisinger, Physics and Astronomy Department, University of Canterbury