How Henri Poincaré defended the case of Alfred Dreyfus during the anti-Semitic era in France

You will better understand why I am an admirer of Henri Poincaré: not only he was a great scientific discoverer but he was also courageous enough to publicly bring back intellectual honesty that is so lacking today in "scientific" community. Science and scientists should not be the intellectual prostitutes of Political Agenda.

Dreyfus, a graduate of both the elite École polytechnique - like Henri Poincaré - and of École Supérieure de Guerre [War School], was a promising young artillery officer in the French Army. His high exit rankings in both these institutions had placed him on a fast track which had led to a training position on the Army's General Staff in 1894. Dreyfus came from an old and prosperous Jewish family that had made its fortune in a textile business in Mulhouse, Alsace when that province was still a part of France. After the French defeat in 1871 and the annexation of Alsace by Germany, the entire Dreyfus family chose to remain French and moved to France.

In October 1894, Dreyfus was arrested and charged with passing military secrets to the German Embassy in Paris. He was convicted of treason by a military tribunal in December 1894 and promptly imprisoned on Devil's Island, a prison island off the coast of French Guiana. The conviction was based on a handwritten list offering access to secret French military information. The list had been retrieved from the waste paper basket of the German military attaché, Major Max von Schwartzkoppen, by an Alsatian cleaning woman employed by French counter-intelligence.

French Jewish people in the 1890s were in a better situation than Jews in other European states such as Germany. Nevertheless Anti-Semitism was also pervasive in France. So the Dreyfus affair became a political scandal which divided the Country from the 1890s to the early 1900s.

In 1899 Dreyfus asked for a Revision of his Trial "Le Procès de Rennes" in a letter to the Minister of Justice.

On September 4, 1899, at the Conseil de guerre de Rennes [War Council of Rennes], the French mathematician Paul Painleve (1863-1933) asked permission to read a letter Poincare had sent to him. In this 'epistola' Poincare criticized the methods of analysis performed in the notorious 'bordereau'. Henri Poincare, alluding to an article appeared in a special issue of the newspaper Le Figaro, stated that the stochastic [provbabilistic] reasoning used by Alphonse Bertillon (1853-1914) was flawed. His letter ended as follows:

"... l'application du calcul des probabilites aux sciences morales est, comme l'a dit je ne sais plus qui, le scandale des mathematiques! ... Rien de tout cela n'a de caractere scientifique, et je ne puis comprendre vos inquietudes. Je ne sais si l'accuse sera condamne, mais s'il l'est, ce sera sur d'autres preuves. Il est impossible qu'une pareille argumentation fasse quelque impression sur des hommes sans parti pris et qui ont recu une education scientifique solide ..."

As I'm french I can translate into English (forgive me if my english is not very good !):

"… the implementation of the probability theory to moral sciences, as someone whom I don't remember said, is the scandal of mathematics! … Nothing of all that has scientific character, and I can't understand your worries. I do not know if Dreyfus will be condemned, but if ever he is, it shall be on the other evidences. It is impossible that such argumentation can make any impression on men without bias and who received a solid scientific education…"

On April 18, 1904, Henri Poincare, Gaston Darboux, and Paul Appell were appointed by the Chambre criminelle de la Cour de cassation to study and then report, from a scientific standpoint, the work of Bertillon, especially the authenticity of the 'bordereau'. In 1906 Dreyfus was entirely rehabilited.