More precisely: Who is the most loathsome philosopher in his or her personal life?
Let me set the bar high by naming my top two candidates.
1. Jean-Jacques Rousseau, who fathered several children and had them abandoned to orphanages, and of whom David Hume wrote in a letter to Adam Smith: “Thus you see, he is a Composition of Whim, Affectation, Wickedness, Vanity, and Inquietude, with a very small, if any Ingredient of Madness. … The ruling Qualities abovementioned, together with Ingratitude, Ferocity, and Lying, I need not mention, Eloquence and Invention, form the whole of the Composition.” (David Hume, letter to Adam Smith, October 8, 1767 [Correspondence, 135])
2. Martin Heidegger, who was a Nazi and who, his lover Hannah Arendt said, “lies notoriously always and everywhere, and whenever he can.”
I am open to other suggestions.
Some follow up questions. When one disagrees profoundly with an intellectual’s philosophy, as I do with Rousseau’s and Heidegger’s, is it legitimate to look for a connection between the philosophical and the personal? Or can deep philosophy vary completely independently of personal behavior? Is ad hominem ever a legitimate argument strategy? One should expect integrity, especially from philosophers — i.e., that they will live what they teach and teach what they live — but we also know that hypocrisy is widespread. Should it matter now that influential philosophers were personally immoral, or do only their ideas and arguments matter now?
Related posts on Heidegger:
Nazism and education [Section 14 of Nietzsche and the Nazis].
Heidegger, anti-humanism, and the Left.
Heidegger and postmodernism [Excerpt from Chapter 3 of Explaining Postmodernism].
Interview with director Jeffrey van Davis on Heidegger and Nazism.