Étienne Émile Marie Boutroux was an eminent 19th-century French philosopher of science and religion, and a historian of philosophy. He was a firm opponent of materialism in science. He was a spiritual philosopher who defended the idea that religion and science are compatible at a time when the power of science was rising inexorably. His work is overshadowed in the English-speaking world by that of the more celebrated Henri Bergson. He was elected membership of the Academy of Moral and Political Sciences in 1898 and in 1912 to the Académie française.

Jules Henri Poincaré was a French mathematician, theoretical physicist, engineer, and philosopher of science. He is often described as a polymath, and in mathematics as "The Last Universalist", since he excelled in all fields of the discipline as it existed during his lifetime. Due to his scientific success, influence and his discoveries, he has been deemed "the philosopher par excellence of modern science."