This paper considers the method of idealization and factualization as the main method of all advanced empirical science. The procedure is as follows. Some idealizing conditions are assumed: the vanishing of factors $(p_{i}=0)$ which never vanish in the real world. An idealization law is formulated -- a law which is exactly (non-vacuously) fulfilled only in an ideal model, not in any real system. Then the idealizing assumptions are abrogated one by one-it is a process of gradual factualization, of the transition (...) to the factual laws which are fulfilled in real systems. These laws may be directly applied and tested by experience. (shrink)

This pioneering work in the history of science, which originated in a series of three Gauss Seminars given at Princeton University in 1984, demonstrated how the roots of the scientific revolution lay in medieval scholasticism.