History of science is, in its current self-image, a nonjudgemental discipline. Most present-day historians of science believe that assessments of past science on such criteria as rationality, validity, empirical adequacy, and correctness do not fall within their scope. Their task is to reconstruct the deeds and claims of past scientists, not to ascertain the merits of past scientific contributions.

It has not always been thus. An earlier generation of historians of science took it for granted that they should compare past science to present-day science; they also expected that present-day science would emerge comprehensively the winner in this comparison. This was the period of Whig historiography of science.

The evaluative mission of Whig historiography was founded on, and made possible by, the practice of rendering past claims and deeds straightforwardly in present-day terms. This practice highlighted apparent coincidences and differences between past science and present-day science. Any discrepancies were debited to the scientists of the past.

Whig historiography was gradually succeeded by a different approach. This prescribed understanding past contributions in terms of their own problems and conceptions, rather than as an imperfect approximation to present-day science. This approach was sustained by the principle that contributions should be understood in the terms of the actors themselves, avoiding all anachronistic categories. This principle restricts, for example, use of the category "science" itself to the very recent past. In this approach, there is no basis for appraisals of scientific work beyond those that the actors themselves made. Historians treat even these with detachment, since for every actor that disparages some piece of work, there is another actor whose work this was.

This new approach has yielded a large output of exceptionally valuable historiography, whose picture of science is much more convincing than Whig accounts. There are also, however, reasons for regarding the abandonment of an evaluative role as a loss. Evaluations of past science have value in several different contexts. In history of science itself, they might provide a basis for a more analytical treatment of "winners" and "losers" in scientific controversies, which in recent historiography are treated rigorously even-handedly. In philosophy of science, they would provide evidence in the debate between scientific realism and instrumentalism, which often turn on the alleged quality of and improvement in past theories. In general intellectual contexts, they would help us gauge the degree and nature of scientific progress over historical timescales, an interesting issue from anyone’s standpoint.

Project 2 will be devoted to the question whether it is possible to formulate a new conceptual foundation for attributing an evaluative role to historiography of science, without relinquishing the historiographic sensitivity of recent work in the discipline.

Project 2 will:

• Discuss what epistemological and methodological conditions must hold in order for assessments of past science on criteria of rationality, validity, empirical adequacy, and correctness to be possible.
• Ascertain in what historiographic contexts these conditions hold.
• Analyze the reluctance of recent historiography of science to undertake such assessments, and provide arguments for overcoming it.
• Construct sample assessments of past contributions to science, and discuss their cogency, reliability, and utility.

The initial working hypotheses of Project 2 are the following:

• Historiography of science depends to some extent on systematic assumptions about the behaviour and pattern of inference of past scientists. Concealing these assumptions only hinders historiography.
• Whereas the insistence on using only actors’ categories in reconstructing past science is heuristically valuable, the advice is both conceptually dubious and pragmatically unattainable. It is acceptable to make use of present-day categories of certain kinds, especially with regard to the evidential relation between past claims and empirical evidence.
• The assumption—widespread in recent historiography—of a principle of interpretative charity towards past work, which enjoins the historian to adopt the most favourable interpretation of any ambiguous evidence, is not warranted. It should be replaced by an evaluative circle in which the rationality and validity of past contributions are judged in the light of all evidence.

While challenging some assumptions of recent historiography, Project 2 will also build upon some of its output. There has been growing interest recently among historians of science in re-staging historical scientific experiments, such as Galileo Galilei’s inclined plane experiments on accelerated motion in the 1600s and James Joule’s paddle wheel experiment on the mechanical equivalent of heat in the 1840s. Some re-stagings are performed for didactic purposes, but it is also possible to use the empirical data to evaluate the original experiment for, for example, precision, replicability, and persuasive power. Project 2 will use the concept of re-staging historical experiments as one of the entry points for evaluations of past scientific contributions.

• historiography of science
• history of science
• philosophy of science
• science studies