For Thomas Kuhn normal science consists of moping up exercises. (SSR, 24) What Kuhn means by this can only be explicated further when one understands what he means by paradigms.
While many understand the history of science to be a continuous chain of discoveries and enlightenment, in The Structure of Scientific Revolutions Thomas Kuhn suggests another picture. For him science is characterized by both continuity and discontinuity. The continuity of science is found in temporally located research traditions, i.e. paradigms, while the discontinuity is found in the transitions that take place from one paradigm to another. Kuhn constitutes these transitions as revolutions because they consist in a radical transformation of the way the scientific community views the world in which its work takes place and the work of science itself. Paradigms share two essential characteristics: 1.) When compared with the competing theories of their day paradigms succeed at addressing vexing issues in such a way that they attract the majority of scientists as adherents, 2.) Paradigms themselves must be open ended enough to leave all manner of puzzles for the adherents to solve. (10, 23) Paradigms set the parameters for science and thus bring stability to scientific research. They suggest the questions worth asking, the methods for asking and the methods for answering such questions, the tools which will be needed for investigation, and they create a solid starting point—the way the world actually is (5, 42)—from which scientists can attack acute puzzles with rigor without having to rearticulate the underlying presuppositions of a research paradigm every time. (17-19) Paradigms supply the relatively inflexible boxes within which normal science proceeds. (24)
Kuhn suggests that at the beginning paradigms are largely a promise that under their regime problems will be solved. (23) This gets us to the moping up work of normal science. Normal science extends the knowledge of the facts that a paradigm considers revealing, increases the match between these facts and the paradigm’s predictions, and further articulates the paradigm. (24) The scientific fields that Kuhn uses as examples are chemistry, early electricity, geology, and physics (astronomy and optics). These examples are all “paradigmatic” for Kuhn’s theory because they have all gone through paradigm shifts.
As normal science functions within a particular paradigm it is carried out through three fundamental kinds of activities, which I have already alluded to. (34) The first of these is the determination of significant facts. Kuhn breaks these into “three normal foci” (25): 1.) Those facts that the paradigm has considered particularly revealing of the nature of things, 2.) those facts that can be compared with the paradigm’s predictions, and 3.) those facts gathered through empirical work that allow for the further articulation of the paradigm, i.e. those that aim at determining physical constants, quantitative laws, and the qualitative application of the paradigm to other area’s of interest. (25-29)
The second kind of fundamental activity for normal science is the matching of facts with theory. This proves to be an incredibly tricky practice and thus leads to the manipulation of the theor so that it can be confronted directly with experiment. (30) This also leads to new applications of the theory.
The third, and last, of the fundamental activities of normal science is the articulation of the paradigm. At times clarifying through reformulation does this. Yet, this reformulation is a reflexive process in-so-far-as it produces substantial changes in the paradigm itself. Therefore, the articulation of a paradigm is a dynamic process which proceeds through both experiment and theorizing. (33-34)
The last aspect that must be considered for this section is Kuhn’s characterization of science as puzzle solving. Kuhn suggests that puzzles are specific problems that can test ingenuity or skill in solution. Puzzles are always solvable. (36-37) Paradigms provide scientific communities with the criterion for deciding which problems are puzzles. The fact that puzzles can be solved allows scientists to attack precise problems. Puzzles within paradigms are also characterized by rules that limit the nature of acceptable solutions and the steps by which these solutions are to be obtained. (38) Kuhn places these rules into a few overarching categories. There are, for one, the explicit statements of scientific laws, concepts, and theories. Second, there are commitments to preferred types of instrumentalization and their proper use. Third, a paradigm provides a set of shared metaphysical and methodological commitments, i.e. what sort of entities the world contains as well as what sets of laws and fundamental explanations. Finally, the scientist must be committed to the rigorous and methodical scientific quest. Kuhn wishes to make clear that a paradigm is more fundamental than such rules. (44) Paradigms consist of a set of commitments, beliefs, rules and methodologies that are connected through a family resemblance, in a Wittgensteinian sense. (45) Thus, rules can be but are not always shared by members of a particular paradigm.