Michel Foucault developed the concept of parrhesia as a mode of discourse in which one speaks openly and truthfully about one's opinions and ideas without the use of rhetoric, manipulation, or generalization. Foucault's use of parrhesia, he tells us, is troubled by our modern day Cartesian model of evidential necessity. For Descartes, truth is the same as the undeniable. Whatever can be doubted must be, and, thus, speech that is not examined or criticized does not necessarily have a valid relation to truth.