Symbolic Generalisation

In the closing paragraphs of Chapter II of the Structure of Scientific Revolutions (SSR, II), Kuhn notes the importance of "esoteric" modes of publication, or what he also calls research "communiqués", for the emergence of normal science or research carried out within what he comes to call a "disciplinary matrix". These are very efficient ways of communicating research results to peers, but largely incomprehensible to lay people. The problem for the lay person, of course, arises from the high degree to which the research can (and does) take the meaning of central terms for granted. In the second section of the post-script (SSR, PS, 2), Kuhn identifies this capacity to be precise with the presence of "symbolic generalisations" in the language used by a research community. It is with the use of these generalisations, that the "communiqués" are produced, allowing scientists to pass from having to write lengthy treatises that derive all results from fundamentals, to writing short papers that present the result of specialized investigations to people who already know how to make sense of them, i.e., can determine their significance both in the sense of brute 'meaning' and in the sense of the relative 'importance' of the results. In so far as it is unclear what a result means to the research of one's peers, it may be "anomalous" and be an advance indication of crisis and revolution. Only history will tell, however, so at the time it will simply not register, i.e., future contenders for paradigmatic status are ignored in the present on par with past contenders.

The presence of terms that clearly indicate their subject matter to initiated peers, then, is called the "symbolic generalisation" of research within a "disciplinary matrix". Part of describing such a matrix (also called a paradigm, for short) is identifying highly generalised symbols available to the researchers when communicating with each other, and unavailable (at least as a presumption) when communicating with non-peers. (They may run into someone that happens to know what they are talking about, but they can't count on it outside the paradigm.) The sense that is made of the symbols is conditioned by the paradigm, so this will also enter into our epistemological descriptions. Thus, in describing a body of knowledge (a scientific discipline) as a "paradigm", the task of describing its symbolic generalisations consists in two sub-tasks: (a) to identify the symbols that generalize the field and (b) to describe their use, i.e., to determine their meaning. So, while Kuhn warns us at the start of Chapter III, not to let the word "paradigm" mislead us into the thinking of research in general by analogy with grammar (SSR, III), the description of symbolic generalisation is very much a matter of delineating the grammar of a particular discipline's research communication. Paradigmatic results may not often be replicated, but their grammatical structure is.

One very important aspect of this element of epistemological description is the difference between "definitional" and "legislative" applications. Where the same symbols recur among different groups of scientists, different paradigms will sometimes be evident, in part, because the same expressions are used primarily definitionally in one and legislatively in another. So it is important to know the difference, and to identify it as part of the description of a paradigm.

Sometimes a generalization like "f = ma" will be used to define a term (like "f", "force") and therefore stipulate the sorts of operations it would take to render them, e.g., empirically observable. In order to determine the force of a rocket in flight, for example, we must determine its accelaration (by observation of its motion) and its mass (by, hopefully, having weighed it before lift-off). The product of these values, then, just "is" the force of the rocket at a given point: "mass times accelaration" is (part of) what force means. Thus, the "force" of an "impact" understood in terms of (Newtonian) mechanics is evident in the acceleration that the impact causes the thing impacted to undergo.

But at other points in the history of mechanics (or in other uses of the language of mechanics) the same expression, "f = ma", may be a statement of law, i.e., it might impart the knowledge that force is always equal to the mass of a projectile times its acceleration. This knowledge can be very useful when attempting to accelerate or decelerate things like rockets. Kuhn calls such an application of a generalisation its "legislative" use.