Mental Models in the History of Knowledge: The Relation of Practical Experience and Conceptual Structures in the Emergence of Science

The goal of the project is to study the causes and long-term developments of scientific knowledge. The project is focused on mechanics as a part of science with an extraordinary significance for the development of science in general. In particular, more than other disciplines, mechanics has a continuous tradition from its origins in antiquity to the elimination of fundamental categories of mechanics by modern physics. Presently, the scope of the project is restricted to the time period from antiquity to the emergence of classical mechanics in early modern times. It is, however, intended to follow up the research questions of the project to the twentieth century.

The peculiar longevity of mechanics has given rise to speculations that the experiential basis of such scientific knowledge must be of a special kind, distinct from that of other sciences which emerged much later. It has been claimed, for instance, that knowledge in mechanics or in mathematics is rooted in an essentially universal everyday experience or even based on a priori structures of thinking. These and other speculations involve a very restrictive notion of experience, however. They exclude the by no means universal experience that human beings acquire in a historically specific material environment when dealing, for example, with the technology of their times. Therefore, the project is particularly focused on the historical reconstruction of such collective, practical experiences and their influences on the structure and content of scientific knowledge. Its main goal is to study the role of practical experience for the emergence and development of fundamental scientific concepts of mechanics, such as those of space, matter, force, time, and motion, and to reconstruct the patterns of explanation they were used for.

An analysis of the relation between the various layers of knowledge and their development requires an appropriate description of their architecture. Evidently, formal logic is of little help here. In contrast to the inferences of formal logic, scientific conclusions can be corrected. Not only scientific knowledge but in fact large domains of human experience are not simply lost when theories are revised, even if this knowledge does not explicitly appear in such theories. In our description of the architecture of scientific knowledge we therefore make use of concepts from default logic such as the concept of a mental model, adapting them to an account of the historical development of the shared knowledge at the basis of science. We conceive of mental models as knowledge representation structures based on default logic which allow for drawing inferences from prior experiences about complex objects and processes even when only incomplete information on them is available. Mental models relevant to the history of mechanics either belong to generally shared knowledge or to the shared knowledge of specific groups. Accordingly, they can be related either to intuitive, to practical, or to theoretical knowledge. They are, in any case, characterized by a remarkable longevity even across historical breaks, as becomes clear when considering such examples as the mental models of an atom, of a balance, of the center of gravity, or of positional weight. Their persistence in shaping the shared knowledge documented by the historical sources becomes particularly apparent in the consistency of the terminology used, a consistency that offers one important element for an empirical control for the reconstruction of such mental models and their historical development.

The project traces the basic mental models of mechanical knowledge and their development across a large historical time span which may be divided into the following six major periods, the first four of which are presently in the focus of the ongoing research. The first period may simply be called the "prehistory of mechanics"; it comprises the long period of time in which human cultures have accumulated practical mechanical knowledge without documenting this knowledge in written form and without developing theories about this knowledge. The second period is that which properly merits the label "the origin of mechanics." It is characterized by the appearance of the first written treatises dedicated to mechanics and to physics, associated in particular with names such as Aristotle, Euclid, Archimedes, and Heron. The third period is, in its beginning, characterized by the transformation of mechanics into a "science of balances and weights." This period covers the Arab and Latin Middle Ages which saw the production of an extensive mechanical literature focused, however, on a relatively small range of subjects. The fourth period is that of preclassical mechanics, ranging from the sketches of Renaissance engineers such as Leonardo da Vinci to the mature works of Galileo Galilei. In contrast to the preceding period it deals with an increasingly large number of subjects, among them the inclined plane, the pendulum, the stability of matter, the spring, etc. The fifth period is that of the "rise of a mechanical world view." It extends from the first comprehensive visions of a mechanical cosmos such as that of Descartes, via the establishment of classical and later analytical mechanics, to the attempts of nineteenth century scientists to build physics on an entirely mechanical basis. The sixth period is that of the decline of the mechanical world view and the disintegration of mechanics at the turn from the nineteenth to the twentieth century, associated with the emergence of modern physics and its conceptual revolutions represented by the relativity and quantum theories.