Gottfried and Wilson reply

Models developed in the search for a new scientific theory are, by definition, only communal belief systems with a dubious grip on reality. Our disagreement with the strong programme in the sociology of scientific knowledge (SSK) is its resistance to accounting for the profound transformation of knowledge that is created when the search for a theory succeeds. The ‘old’ particle physics was such a belief system, whereas the ‘new’ physics — the standard model — differs from the ‘old’ in the sense that quantum mechanics differs from the inconsistent and fragmentary recipes of the old quantum theory, the latter's successes and seminal role notwithstanding.

The problem, as we see it, stems in good measure from the ways in which history and prediction are handled in SSK following the birth of a new theory. Perhaps our views on these issues were not stated clearly enough, for we have been misunderstood.

Of course we agree that retrospective (‘Whig’) history has no place in analyses of how science is created, and said so explicitly. But SSK accounts often treat only the earliest phases of a scientific development, when the evidence is uncertain, and largely ignore subsequent convincing confirmations. Furthermore, SSK does not confine itself to the creation of practice and knowledge. It also makes sweeping, and at times flamboyant, Last Judgements about scientific practice and knowledge as a whole, as in the concluding chapters of The Golem5 and Constructing Quarks2. It is this aspect of the SSK literature that is our first concern, for these judgements can be ‘understood’ by laymen and schoolchildren, whereas the technical parts of the case studies cannot.

As to prediction, of course “later predictive success cannot be appealed to as a cause of earlier acceptance”. We made no such appeal in bringing up chaotic motion in the Solar System and the Planck spectrum of the cosmic background radiation, which were discovered long after classical mechanics and the quantum theory had become firmly accepted. They are among many examples that illustrate the astonishing (and mysterious) ability of science to account for phenomena of which no inkling was available when the relevant theories were first accepted. The SSK literature is biased because it does not include case studies of such episodes, nor of experiments that test established theory to high accuracy.

Rather, it devotes great attention to two other topics: first, to the undeniable fact that scientific practice and knowledge rarely conform to any known set of philosophical ground rules; second, to features of scientific knowledge that are common to knowledge as a whole. Such commonalities abound; scientific knowledge is generated in ways that have typically human characteristics. But the end product is very different from those of virtually all other human activities.

SSK argues that scientists make choices contingent on culture. There is truth to this. But if that were all — if there were as much freedom to choose as SSK claims — a good portion of the major theories whose acceptance had been successfully ‘negotiated’ should fail disastrously in regimes where they were supposed to work, as popular policies often do in a democracy. Why scientific knowledge is, in contrast, so robust is not explained by the canon of SSK.

Collins and Pinch say that the “evaluation of scientific findings is not our business” (a position they share with Bloor and MacKenzie). Pickering, in contrast, evaluates the findings of particle physics in part as a former professional particle physicist with his own unusual scientific views (see pages 250-252 of ref. 4).

Constructing Quarks is a “best, empirical, case-study”, to use Bloor and MacKenzie's term. Nevertheless, having been active participants in the move to the new physics, we disagree with Pickering's conclusion that “objective merit” was not “what induced most physicists to move”. Indeed, consider the following statement in Pickering's account (see page 411 of ref. 2): “⃛the world of the old physics was conceptually and socially fragmented. Traditions organized around different phenomena generated little support for one another.⃛ With the advent of the new physics, the conceptual unification of forces was accompanied by a social unification of practice. The quark-gauge theory world view was at the heart of a community-wide symbiosis of experiment and theory.”

As our essay explained, we agree with an edited version of this statement; the old physics was fragmented because there were few theoretical connections between its various models and recipes, whereas the new was a powerful theory that provided a unified account and unambiguous predictions, some of which were quickly confirmed. Pickering means his statement to be read as saying that unification was primarily a social phenomenon, “a communal search for a congenial world: a world in which practice could be socially organized”, and it is this claim that underlies his final verdict against the objectivity of modern science.

Finally, to Capasso's excellent letter. We set technology aside because we could not do justice to it in the space allotted. Technology plays an essential role as both input and output in the processes of continuous improvement of scientific practice and knowledge after a theory is born, a topic to which SSK gives little notice. This is part of a larger problem we often encounter in the SSK literature: an inadequate description of the culture of physics — of the conceptual, historical and technological context in which research in modern physics is actually done.