Lunatics also change their minds, but their minds change with the tides of the moon

From Experiments in Philosophical Genre: Descartes’ Meditations, Critical Inquiry 9, no. 3 (March 1983): 545–65, at 562. by Amélie Oksenberg Rorty. 

What is crucial is our ability to engage in continuous conversation, testing one another, discovering our hidden presuppositions, changing our minds because we have listened to the voices of our fellows. Lunatics also change their minds, but their minds change with the tides of the moon and not because they have listened, really listened, to their friends’ questions and objections.