While the positivists were in an ongoing stalemate regarding how science ought to be conducted, the most significant challenge to the positivists' 'Rational Reconstruction' of scientific reasoning came not from a philosopher, but from a historian. Kuhn upended the philosophers’ aspirations to make explicit the underlying reasons behind the methods, decisions, and practices of science. To Kuhn, the philosophers’ contention of the scientific method overlooks how actual science gets done. Thomas Kuhn, a physicist turned historian for philosophical purposes, authored what is arguably the most important book in the philosophy of science: "The Structure of Scientific Revolutions."
The method and its justification, to Kuhn, are already embodied in the success of science, not in some philosopher’s conception of method. The way to understand what’s special about science is not to investigate some underlying method or logic, but rather to look at the actual mechanisms through which scientific practices have been adopted or modified. Kuhn places his bets on the history of science rather than on the methodology of the philosophers: we have to look into how inquiries have been done in order to decide how inquiries should be done.
Given what science have been able to achieve, if philosophers say science should be done in a way different than how it is done, then that’s a problem for philosophers’ models. What science has actually accomplished should take precedence over what philosophers say it should be doing instead.
The title of the book tricks us into believing Kuhn will be saying a lot about revolutions in science, but he writes about ‘normal science’, not revolutionary science, about two-thirds of the book. Heroic science does occur, according to Kuhn; but if one wants to understand how science as an enterprise works, one has to understand what most scientists do most of the time, which is normal science. However, Kuhn had some revolutionary things to say about normal science. The most significant assertion Kuhn draws here is that science is more dogmatic than we had previously thought, quite the opposite of the Popperian utopia where hypotheses are constantly in the face of falsification.
In order to move forward, we need to understand a term Kuhn uses quite liberally throughout his book without giving a precise definition- Paradigm. A paradigm can be considered a dominant set of scientific theories, methodologies, practices, and shared assumptions that define a particular scientific discipline at a given time. A paradigm is an object of consensus. Normal science is governed by a certain paradigm.
A good scientific education teaches us how to solve new problems using theories we’ve already learned. The way it does so is by providing models that can be used to cover new cases. Scientists learn concrete textbook models, and they then extend those models to new cases. These models are implicit in the paradigms, and this implicit consensus-building process makes science so successful. To Kuhn, this consensus is what distinguishes science from other endeavours. At times, it may seem as if the scientific community bears resemblance to a cult.
Puzzle solving is Kuhn’s analogue of the paradigm. The paradigm identifies the puzzles, governs expectations, assures scientists that each puzzle has a solution, provides standards for evaluating the individual solution to other solutions. For instance, Newton’s theories tell scientists what kind of forces there are, how those forces are to be used to explain motion. It tells them what sorts of questions to ask, and which problem is important to solve.
Immature sciences, originating from a new paradigm, become sciences once one of the competing paradigms scores a decisive victory. Then the victor’s paradigm writes history according to its own standards. It is the ongoing competition between paradigms that leads to philosophy of science, not the other way around.
Now, here is the biggest distinction from Popper. For Kuhn, scientists are not trying to falsify the theories behind the paradigm at all. They are assuming the paradigm is correct. They are trying to fit nature into the paradigm. A scientist’s day to day work is small scale and detail oriented. It focuses on one small part of nature being assimilated into the paradigm. This pedestrian depiction of science has upset quite a few philosophers I will later discuss.
Normal science, then, is very much anti-Popperian. It is much more dogmatic than it is open minded. It involves theories being preserved in the face of falsifying evidence, not rejected.
Normal science possesses a notable Popperian virtue: the capacity to undermine itself. When a scientific paradigm no longer maintains its hold on the scientific community, a scientific crisis ensues. According to Kuhn, crises arise due to anomalies, as scientists may confront the paradigm's resistance to fit. This state of crisis generates a heightened curiosity about the philosophy of science. In this way, Popper wasn’t wrong- he took ‘crisis science’ for ‘normal science’.
Ultimately, Kuhn's depiction of normal science isn't a critique but an ode. Kuhn contends that science requires periods of stability, as opposed to unending crises and debates, in order to achieve significant advancements. Normal science, with its inherent dogmatism, has the capacity to produce anomalies that can trigger revolutionary shifts, thus establishing an equilibrium between continuity and transformation. Normal science with its meticulous and frequent inquiry often exposes discrepancies between the established paradigm and reality. This level of focus would not be possible to attain in the Popperian framework, where scientists' primary aim is to falsify the paradigm.