On the Philosophical Import of Some Accomplishments of Newton da Costa

From Newton da Costa’s works, many people in France know only the revival of paraconsistency. We give some reasons in defence of investigations in this part of logic. But above all we recall one of the major contributions of Newton da Costa: his proof, in 1991, in collaboration with Doria, of the g delian undecidability of motion in mathematical physics, a result which was somewhat foreseen on other grounds by Duhem in 1906.