Pierre Alexandre Ildefonse Isaac (9 January 1845 – 5 August 1899) was a French lawyer who was a left-leaning Senator of Guadeloupe from 1885 until his death in 1899.

[2] The Isaacs were educated and wealthy, and were among a small number of people of mixed race who had managed to join the political and economic elite of the island.

[7] According to the black socialist politician Hégésippe Légitimus the Isaac brothers had betrayed the people of the island for the sake of their political ambitions.

[4] In the Senate he sat with the left, voted with the majority and participated in debates on topics such as primary education, sugar, the insane, the proposals by Anselme Batbie(fr) concerning nationality, relationships between France and the Dominican Republic, organization of Indochina, colonial reform and the naval budget.

He voted for establishment of the district ballot, for the Lisbonne law restricting freedom of the press and for the Senate process against General Boulanger.

The explorer Gustave Le Bon argued that attempts to educate the "inferior races" of the colonies would only cause them misery.

Isaac opposed this view, reminded the audience of the ideals of the French Revolution and said he could not understand how education could be held to be a bad thing.

He noted that Algerian indigenous people were already subject to most aspects of French law, and the settlers also benefited from legal exemptions.

He issued a report on 15 March 1898 in which he asked the Algerian committee to end the system of attachment that Albert Grévy had started in 1881, and that had been expanded by Louis Tirman between then and 1891.

[13] At an early meeting he pointed out that although the Dreyfus affair was absorbing, there were many other examples of injustice that demanded action, such as the plight of the Algerian Jews.