Thomas Nagel on Nonrational Rationality
The Last Word (New York: Oxford University Press, 1997), pp. 115-6.Suppose you become convinced that all your choices, decisions, and conclusions were determined by rationally arbitrary features of your psychological makeup or by external manipulation, and then tried to ask yourself what, in the light of this information, you should do or believe. There would really be no way to answer the question. Because the arbitrary causal control of which you had become convinced would apply to whatever you said or decided. You could not simultaneously believe this about yourself and try to make a free, rational choice. Not only that, but if the very belief in the causal system of control was itself a product of what you thought to be reasoning, then it too would lose its status as a belief freely arrived at, and your attitude toward it would have to change. ¶ Doubt about your own rationality is unstable; it leaves you really with nothing to think. So although the hypothesis of nonrational control seems a contingent possibility, it is no more possible to entertain it with regard to yourself than it is to consider the possibility that you are not thinking. I have never known how to respond to this conundrum.