Christian Leduc

Leibniz’s universal characteristic is a fundamental aspect of his theory of cognition. Without symbols or characters it would be difficult for the human mind to define several concepts and to achieve many demonstrations. In most disciplines, and particularly in mathematics, the mind must then focus on symbols and their combinatorial rules rather than on mental contents. For Leibniz, mental perception is most of the time too confused for attaining distinct notions and valid deductions. In this paper, I argue that the functions of symbolization differ depending upon the kind of concepts that are replaced with characters. In my view, most commentators did not sufficiently underline the distinction between two main functions of formal substitution in Leibniz’s characteristic: either increasing our knowledge or simply structuring it. In the first case, we complete our knowledge because formal substitution makes sensible and imaginary concepts more distinct. In the second case, symbolization helps to organize contents that are already conceived of by reason. Thus the process of substitution is not always identically applicable, for symbols replace different types of concepts

In this paper, I show that Maupertuis and Euler offer a contrasting conception of metaphysics of nature. It consists mainly for them in repositioning cosmology in relation to natural sciences. Instead of considering metaphysics to be at the foundation of scientific theories, as was assumed by Descartes, Wolff, and, in a certain way, Kant, or simply prohibiting the very idea of a cosmology, as d’Alembert would stipulate at the same period, Maupertuis and Euler invert the order of disciplines to give priority to physical sciences over metaphysics. This repositioning leads of course to several questions : first, how does scientific theories validate or deny metaphysical principles? Even more important, which role falls to metaphysics of nature given that sciences not only possess a theoretical autonomy, but also a priority over ontological reflections? Besides, it seems that metaphysics would be reduced, for these two philosophers, to the realm of cosmology alone, in particular to questions concerning force and the principle of least action, the ontological status of space and time, and the first constituents of matter, such as extension, inertia, impenetrability, and motion.

Le principe de l’identité des indiscernables constitue l’un des aspects essentiels de la métaphysique leibnizienne de la substance. Il implique notamment que toute substance s’individualise par la totalité infinie de ses propriétés. Sur le plan épistémologique, ce principe pose toutefois problème: comment un entendement fini parvient-il à se représenter les individus, sachant que seul l’entendement de Dieu possède la capacité de connaître la série infinie des propriétés qui individualise la substance? L’auteur vise ici un double objectif : d’une part, démontrer qu’il existe chez Leibniz une philosophie de la connaissance suffisamment distincte des autres disciplines, notamment de la logique et de la métaphysique. D’autre part, examiner l’impact de cette épistémologie sur la théorie de l’individuation. Il s’agit d’analyser les différents moyens employés par Leibniz pour expliquer la conception des êtres individuels du point de vue de la représentation humaine.