Article révisé par les pairs
Résumé : In this paper, we show that by looking for the logical principles of Spinoza's Ethics by looking into its core constituents (that is to say, its definitions, axioms and postulates) one can realise that a logical mistake has been made in the proof of the seventh Proposition of the first Part (E1P7d), which is about the existence of the substance. This mistake comes from the fact that the word self-caused, defined in the first Definition of the same Part (E1D1), bears in it its regular meaning in one case, and the one given by E1D1 in another one. Which is, by Spinoza's own rules, a logical mistake, for he uses E1D1 as an axiom, and not as a definition. However, this mistake can be amended either by changing E1D1 into an axiom or by switching its definiens and its definiendum. But we show then, finally, that both of these rectifications would entail opposing results in regard to the metaphysics, especially concerning which relates to the matter of the existence of the substance, namely, of God.