Is it a contradiction, a lie, a madness, a freedom to affirm a theory and live the opposite? Rousseau writes a treatise on education thanks to the abandonment of his five children, Kierkegaard composes religious texts while living as a libertine, Beauvoir founds the philosophy of feminism while enjoying a servile relationship with her American lover, Foucault exalts the courage of truth and organizes the secrecy of his Aids, Deleuze hates traveling and becomes the philosopher of nomadism...Who are we when we think? Several, no doubt, as shown by the thinkers who invent multiple personalities through their theories. Instead of denouncing their errors or hypocrisy, Francois Noudelmann studies the most complex lie, the one towards oneself, through the anxieties, fugues, and metamorphoses of these double-sided philosophers.