In this essay I examine and discuss the concept “system of philosophy” as a methodological tool in the history of philosophy; I do so in two moves. First I analyze the historical origin of the concept in the seventeenth and eighteenth centuries. Thereafter I undertake a discussion of its methodological weaknesses–a discussion that is not only relevant to the writing of history of philosophy in the seventeenth and eighteenth centuries, but also to the writing of history of philosophy in our times, where the concept remains an important methodological tool.

My first move is to analyze Jacob Brucker's employment of the concept in his influential history of philosophy, Historia critica philosophiae, dating from 1742–1744. To Brucker, a “system of philosophy” is characterized by the following four features: (a) it is autonomous in regard to other, non-philosophical disciplines; (b) all doctrines stated within the various branches of philosophy can be deduced from one principle; (c) as an autonomous system it comprises all branches of philosophy; (d) the doctrines stated within these various branches of philosophy are internally coherent. Brucker employed the concept on the entire history of philosophy, and he gave it a defining role in regard to two other methodological concepts, namely “eclecticism” and “syncretism,” which he regarded as more or less successful forms of systematic philosophy.

My second move is to point out the weakness of the concept of “system of philosophy” as a methodological tool in the history of philosophy. I argue that the interdisciplinary nature of much premodern philosophy makes Brucker's methodological concept “system of philosophy” inadequate, and that we may be better off leaving it behind in our future exploration of premodern philosophy.