Is the reason always right in its own domain?
Reason? Yes. If it is really reason, it is right. It is not absolutely right if one looks at things from the spiritual point of view, for it understands nothing in these domains, but from the rational point of view it is naturally the sovereign judge.
For everything that concerns the ordinary life, and as I say, the mental, vital and physical life of man, a perfectly reasonable being, one who lives according to his reason, cannot make a mistake from this point of view. It is only if one says, “Human life restricted to these planes is not complete, nor perfect in these three planes, it is necessary to introduce a fourth one in it, the spiritual or suprarational plane”, then from this point of view we begin to say, “Reason understands nothing of this, and here it must keep quiet and let the suprarational influence work.” But from the viewpoint of the ordinary life, for people who lead the ordinary life, who do not want to do yoga or develop spiritually, reason is certainly an absolute and very recommendable master. People who live according to reason are usually very sattwic and do not commit any kind of excesses or make serious mistakes, they live reasonably. It is only when one comes out of the ordinary life, when one wants to enter a life leading to a spiritual realisation, that the reason has to abdicate. It can help all the same so long as one is not the absolute master of the movements of his mind and vital. As long as these two things are not transformed, to use your reason is very reasonable, because it will help you to master these movements.
Ref : Questions and Answers 1955