He was born at Lorient. His father was a linen-draper from Lorraine, who renounced Protestantism before his second marriage with a Catholic Breton. Jules Simon was the son of this second marriage. The family name was Suisse, which Simon dropped in favour of his third forename. By considerable sacrifice he was enabled to attend a seminary at Vannes, and worked briefly as usher in a school before, in 1833, he became a student at the École Normale in Paris. There he came in contact with Victor Cousin, who sent him to Caen and then to Versailles to teach philosophy. He helped Cousin, without receiving any recognition, in his translations from Plato, and in 1839 became his deputy in the chair of philosophy at the Sorbonne, with the meagre salary of 83 francs per month. He also lectured on the history of philosophy at the École Normale.
At this period he edited the works of Nicolas Malebranche (2 vols, 1842), of Rene Descartes (1842), Bossuet (1842) and of Antoine Arnauld (1843), and in 1844-1845 appeared the two volumes of his Histoire de l'école d'Alexandrie. He became a regular contributor to the Revue des deux mondes, and in 1847, with Amédée Jacques and Émile Saisset, founded the Liberti de penser, with the intention of throwing off the yoke of Cousin, but he retired when Jacques allowed the insertion of an article advocating the principles of collectivism, with which he was at no time in sympathy.
In 1848 he represented the Côtes-du-Nord in the National Assembly, and next year entered the Council of State, but was retired on account of his republican opinions. His refusal to take the oath of allegiance to the government of Louis Napoleon after the coup d'état was followed by his dismissal from his professorship, and he devoted himself to philosophical and political writings of a popular order. Le Devoir (1853), which was translated into modern Greek and Swedish, was followed by La Religion naturelle (1856, Eng. trans., 1887), La Liberté de conscience (1857), La Liberté politique (1859), La Liberté civile (1859), L'Ouvrière (1861), L'Ecole (1864), Le Travail (1866), L'Ouvrier de huit ans (1867) and others.
In 1863 he was returned to the Corps Législatif for the 8th circonscription of the Seine, and supported "les Cinq" in their opposition to the government. He became minister of instruction in the government of National Defence on September 5 1870. After the capitulation of Paris in January 1871 he was sent down to Bordeaux to prevent the resistance of Léon Gambetta to the peace. But at Bordeaux, Gambetta, who had issued a proclamation excluding from the elections those who had been officials under the Empire, was all-powerful. Pretending to dispute Jules Simon's credentials, he issued orders for his arrest. Meanwhile Simon had found means of communication with Paris, and on February 6 was reinforced by Eugene Pelletan, E. Arago and Garnier-Pages. Gambetta resigned, and the ministry of the Interior, though nominally given to Arago, was really in Simon's hands.
Defeated in the département of the Seine, he sat for the Marne in the National Assembly, and resumed the portfolio of Education in the first cabinet of Adolphe Thiers's presidency. He advocated free primary education yet sought to conciliate the clergy by all the means in his power; but no concessions removed the hostility of Dupanloup, who presided over the commission appointed to consider his draft of an elementary education bill. The reforms he was actually able to carry out were concerned with secondary education. He encouraged the study of living languages, and limited the attention given to the making of Latin verse; he also encouraged independent methods at the École Normale, and set up a school at Rome where members of the French school of Athens should spend some time.
He retained office until a week before the fall of Thiers in 1873. He was regarded by the monarchical right as one of the most dangerous obstacles in the way of a restoration, which he did as much as any man (except perhaps the comte de Chambord himself) to prevent, but by the extreme left he was distrusted for his moderate views, and Gambetta never forgave his victory at Bordeaux. In 1875 he became a member of the Académie française and a life senator, and in 1876, on the resignation of Jules Dufaure, was summoned to form a cabinet. He replaced anti-republican functionaries in the civil service by republicans, and held his own until May 3, 1877, when he adopted a motion carried by a large majority in the Chamber inviting the cabinet to use all means for the repression of clerical agitation.
His clerical enemies then induced Marshal MacMahon to take advantage of a vote on the press law carried in Jules Simon's absence from the Chamber to write him a letter regretting that he no longer preserved his influence in the Chamber, and thus practically demanding his resignation. His resignation in response to this act of the president, known as the "Seize Mai", which he might have resisted by an appeal to the Chamber, proved his ruin, and he never again held office. He justified his action by his fear of providing an opportunity for a coup d'état on the part of the marshal. The rejection (1880) of article 7 of Ferry's Education Act, by which the profession of teaching would have been forbidden to members of non-authorized congregations, was due to his intervention. He was in fact the chief of the left centre opposed to the radicalism of Jules Grévy and Gambetta. He was director of the Gaulois from 1879 to 1881, and his influence in the country among moderate republicans was retained by his articles in the Matin from 1882 onwards, in the Journal des Débats, which he joined in 1886, and in the Temps from 1890.
His own accounts of some of the events in which he had been involved appear in Souvenirs du 4 septembre (1874), Le Gouvernement de M. Thiers (2 vols., 1878), in Mémoires des autres (1889), Nouveaux mémoires des autres (1891) and Les Derniers mémoires des autres (1897), while his sketch of Victor Cousin (1887) was a further contribution to contemporary history. For his personal history, the Premiers mémoires (I900) and Le Soir de ma journée (1902), edited by his son Gustave Simon, may be supplemented by Leon Seche's Figures bretonnes, Jules Simon, sa vie, son œuvre (new ed., 1898), and G Picot, Jules Simon: notice historique (1897); also by many references to periodical literature and collected essays in Hugo P Thieme's Guide bibliographique de la litt. française de 1800 a 1906 (1907).