This paper is devoted to the late Leibnizian doctrine of vinculum substantiale. In the first section I sketch the old problem of possibility of composite substances. This possibility is refuted on the ground of Monadism (presented in section two). However Leibniz’s correspondence with Des Bosses contains new thoughts concerning composite substances. A vinculum enters the stage as a real unifier, transforming aggregates of monads into genuine substances (section three). In the last section I give a systematic interpretation of a vinculum.I (...) start with the thesis that every composed thing, which is not a pure plurality of objects, must have two structures: the whole-parts structure and the subject-properties structure. In the case of substances the latter is ontologically prior over the former. A vinculum is a subject-of-properties (accidents) determining such a way of composition which makes a compound entity a true substance. Since Leibniz still thought a vinculum unifies independent (existentially and with regard to activity) substances he was inclined to separate a vinculum from the integrated monads and finally conceived it as an additional relatively independent monad-like substance. (shrink)

Leibniz’s ‘new science of dynamics’ is typically taken to have been completed in the late monadological metaphysics. On this view, stemming from Martial Gueroult and continuing in the recent interpretations of Robert Adams and Pauline Phemister, Leibniz accomplished his dynamics in his later account of physical forces as merely phenomenal modifications of monadic, metaphysical forces. This paper argues, by contrast, that Leibniz considered the dynamics to be an unfinished project: this is evident in statements from throughout his mature period until (...) his final months. Two possible reasons for the non-completion of the dynamics are discussed. The first is that his encounter with the superior physics of Newton’s Principia caused Leibniz to continually defer his own contribution. I argue, however, in favour of a second reason: that there are philosophical difficulties inherent in the science of dynamics that prevented its completion. These difficulties are found in the relation of dynamics to metaphysics, and in the more fundamental split within dynamics, into the doctrine of primitive and derivative forces. Through three late exchanges with de Volder, Wolff and Des Bosses, I show that the relation of primitive and derivative forces remained an unsolved – although not in principle unsolvable – problem for Leibniz. (shrink)