Arguments

  • Core Logic is not paraconsistent: one proof, six certifications (2026-05-01, updated 2026-07-31) This note provides a proof that asserting Tennant's Core logic \(\mathbb{C}\) to be paraconsistent — by claiming that the antisequent \[\lnot A, A \nvdash B\] is justified in \(\mathbb{C}\) — entails a contradiction within \(\mathbb{C}\) and, consequently, if this paraconsistency claim about \(\mathbb{C}\) is not rejected as false, renders \(\mathbb{C}\) inconsistent. The proof is purely logical and proceeds in four steps within a five-rule fragment \(\mathcal{F}\) of Core logic and its refutation system in the sense of Łukasiewicz and Goranko. Each step has been machine-verified in three certifications — Coq, Lean 4 and Athena — under each of the two structural readings of \(\mathcal{F}\), six in all.
  • Descartes’s First Proof of God’s Existence in First-Order Logic (2021-07-21, updated 2026-07-31) In the language of first-order logic, I provide in this post a proof in natural deduction which translates the argument that Descartes gave as evidence of the existence of God. (A French version of my posts on Anselm and Descartes has been published in the Brasilian Review /Revista de Filosofia moderna e contemporânea/ ( ...

Code

Provers

En français

  • Propositions pour l’enseignement supérieur (2022-12-28) À quelques années de mon départ en retraite, je fais ici quelques propositions de réforme pour l’enseignement supérieur en philosophie. Ce texte n’engage que moi.