Man has only one tool to fight error: reason. Man uses reason in order to choose between the incompatible satisfactions of conflicting desires.
Reason is an ultimate given and cannot be analyzed or questioned by itself. The very existence of human reason is a non-rational fact. The only statement that can be predicated with regard to reason is that it is the mark that distinguishes man from animals and has brought about everything that is specifically human.
To those pretending that man would be happier if he were to renounce the use of reason and try to let himself be guided by intuition and instincts only, no other answer can be given than an analysis of the achievements of human society. In describing the genesis and working of social cooperation, economics provides all the information required for an ultimate decision between reason and unreason. If man considers freeing himself from the supremacy of reason, he must know what he will have to forsake.
Reasoning and scientific inquiry can never bring full ease of mind. He who seeks this must apply to faith and try to quiet his conscience by embracing a creed or a metaphysical doctrine.