Alessandro Becchi

Jan Łukasiewicz, in a series of writings from 1918 to 1946, argued against logical determinism-the idea that the truth or falsity of a statement predetermines future events, thus limiting free will. To defend an indeterministic worldview, he rejected the principle of bivalence and introduced a third value, the ‘indeterminate’, pioneering polyvalent logics. This problem dates back to Aristotle's De interpretatione and the Hellenistic disputes involving Stoics, Epicureans, and Academics. As an expert historian of ancient logic, Łukasiewicz was well acquainted with these debates and employed classical patterns of reasoning in his argument. However, while Łukasiewicz believed that classical logic entails determinism, the author of this text claims that bivalence has no bearing on free will. He argues that the problem arises from a failure to distinguish between different types of truth-bearers (propositions, sentences, assertions) and from a conceptual confusion between causality and logical implication, as Gilbert Ryle pointed out. The author concludes that logical determinism is ultimately a pseudo-problem that has persisted for centuries due to a lack of clear definitions of the key concepts involved in it.

In recent years a certain emphasis has been put by some scholars on Leibniz’s concern about empirical sciences and the relations between such concern and the development of his mature metaphysical system. In this paper I focus on Leibniz’s interest for the microscope and the astonishing discoveries that such instrument made possible in the field of the life sciences during the last part of the Seventeenth century. The observation of physical bodies carried out by the “magnifying glasses” revealed a matter swarming everywhere with life and activity, contrary to the cartesian and atomistic view of matter as something sterile and passive. Moreover, the discovery of uncountable complete “animalcula” living in the smallest drop of water provided evidence for the idea of the preformation of every organism. During his lifetime, Leibniz was extremely watchful about the new microscopical discoveries and came into contact with some of the major “observers” of his time, such as Hooke, Leeuwenhoek, Swammerdam and Malpighi. Relying both on some passages in Leibniz’s texts and on recent critical studies, I will argue that important aspects of his metaphysics have been strongly affected by the empirical observation of the “invisible world” which the microscope made possible. In the last part of the paper I show how the concept of “preformation”, originally drawn from the context of the life sciences, comes to play in Leibnizʼs philosophy a very general role, going far beyond the scope of biology and shaping important aspects of his overall philosophical system.

We edited and translated a so far unpublished manuscript ("Sur la generation des insectes et d'autres petits animaux") drafted by Leibniz in 1714. The text is written on the same paper of the first draft of the "Monadology" and, as we show, there is a connection between these two texts of the late Leibniz, as far as in the "Monadology" , the rejection of the traditional theory of the spontaneous generation of small animals (like insects) is considered by Leibniz as a posteriori confirmation of his preformist theory. In addition to that, this piece shows that Leibniz was deeply influenced by the experimental results in biology and natural sciences, and, especially, by the works of Italian scientits of the Galilean tradition, like Francesco Redi and Antonio Vallisneri.