This paper is intended to analyze the Leibnizian theory of mathematical proof, in relation to his general view on science. Firstly, it provides the main characteristics of Leibniz's method, making a strategic contrast with the Cartesian one (§§ 1-3). Secondly, because for Leibniz the numerical formulae are not primitive logical truths, they require a rigorous formal proof, so that the
... [Show full abstract] corresponding demonstration given in the New Essays is examined in order to gain new insights into the so-called Leibnizian formalism, taking into account as well Frege's and Poincaré's criticisms to it (§§ 4-6). Finally, it offers an evaluative account of all these considerations (§ 7).