L'essenza del corpo. Scienza e filosofia al tempo di Spinoza.

My dissertation considers Spinoza as a representative of the New Natural Philosophy and, in such a role, as a key figure for understanding the non-restrictive meaning of this cultural movement. Indeed, even if Spinoza did not provide any new scientific result, it would be misleading to consider his philosophy as irrelevant for the reshaping of scientia in the Early Modern Era. In my research I make use of two different †" thought connected †" methodological criteria. The first is chronological and requires taking into account the evolution of a problem across the whole time-frame considered. In the case at stake, I devote the first part of my dissertation to investigating how and why issues linked to the concept of body and, more generally, to physics, become real problems for Spinoza. This leads to the important result of reevaluating the first steps of Spinoza's philosophical career, putting the stress on the theological context in which, in the Short Treatise (1661 c.a.), the concept of body appeared for the first time as a challenge: how is it possible to demonstrate that the extension is an attribute of God and thus that finite bodies are modifications of God's infinite substance? In order to answer this question in a feasible way, Spinoza will be forced to work out different further conceptual tools, most notably the mereological part/whole distinction, the status of natural law and the conatus doctrine. My chronological approach shows that the achievements we find in the Ethics (1675) are only the last and most consistent version of Spinoza's philosophy, which underwrite several major changes through his development. This final stage is particularly marked by the centrality of the concept of power as something essential to finite things. I call this conception an “ontology of activity”. This methodological approach allows us to appreciate several key shifts in Spinoza's position and thus to frame in a more determinate way the problem of his sources. The second methodological criteria I use consists, indeed, in considering a “source” not only some “family resemblance” with other authors. Rather, concepts, theories, or issues have to be taken into account insofar as they constitute open questions, about which the authors under examination changed their minds at different point in their works. In the second part of my dissertation, thus, I work out this inquiry following three main lines. Firstly, I address the highly debated question of the dependence of Spinoza's physics on Descartes' own project. I show in particular that in rewriting the second part of Descartes' Principles, Spinoza was committed to a general reinterpretation of several main concepts, and I particularly emphasize the importance that the concept of determinatio assumes in this context. In order to make coherent what in Descartes was indeed deeply ambiguous, Spinoza starts to develop a peculiar conception about physical interactions. From this work, comes a quite interesting account of how physical causality should be interpreted. This conception †" I show †" will remain at the core of the late conatus doctrine presented in the Ethics. As a second step, I explore Spinoza's relationship with two key figures of the English Modern culture in the pre-Newtonian period: Thomas Hobbes and Robert Boyle. I argue that Hobbes could have provided Spinoza with an important framework in which he developed important aspects of his thought, such as the concept of determination and a pure kinematical account of extension. However, I underline also that Hobbes' account of causality turns out to be insufficient to explain Spinoza's mature ontology of activity. Then, I consider Spinoza's relationship with Robert Boyle and I show that it was actually fairly more complicated than what scholars had traditionally admitted. I argue that in his mature stage, Spinoza was not only aware of Boyle's fundamental publications, such as The Origin of Forms and Qualities, but that he ended up by finding in them important elements to conceive of the physical nature of bodies as endowed with active powers to operate in the world. Therefore, I consider Hobbes and Boyle as two reciprocal opposite but not necessarily exclusive boundaries between which Spinoza would have worked out his mature philosophy. As a third and final step, I compare Spinoza's own evolution with the rise of Occasionalism, which was at the same time a chronologically parallel, but philosophically opposite development of Descartes' project. I reconstruct the main physical and epistemological arguments worked out between 1663 and 1666 by Geulincx, Cordemoy and La Forge, before the publication of Malebranche's masterpiece La Recherche de la Verità© (1675). I argue that, on the one hand, these self-styled disciples of Descartes actually provide a quite subversive development of the Cartesian philosophy which often goes explicitly against what Descartes' himself had argued and what his editors †" like Florent Schuyl and Claude Clerselier †" never envisaged. On the other hand, I suggest that Spinoza's ontology of activity is the reversal of Occasionalism. Probably, this is not by chance. On the contrary, I put forward that, in his mature stage, Spinoza would have aimed to stress his distance from those so-called “good Cartesians”, who actually only misinterpreted the issues that Descartes had raised, without being able to provide adequate solutions.