I think the following quote sums up Proust’s philosophy pretty well. As I understand him, he is saying that we use reason to understand our beliefs, not to form them because it isn’t up to the job. Some might call this confirmation bias, but I think Proust was right. I think he is saying that we must have faith in ourselves, in our way of looking at things, faith in the fact that it works, at least for us. This faith is confirmed by experiment, by life itself, as we live it, as we remember and understand what shaped it and what shapes it still.
The fact that our intellect is not the most subtle, the most powerful, the most appropriate instrument for grasping the truth, is only a reason the more for beginning with the intellect, and not with a subconscious intuition, a ready-made faith in presentiments. It is life that, little by little, case by case, enables us to observe that what is most important to our heart, or to our mind, is learned not by reasoning but by other powers. And then it is the intellect itself which, taking note of their superiority, abdicates its sway to them upon reasoned grounds and consents to become their collaborator and their servant. It is faith confirmed by experiment.
Marcel Proust - À la recherche du temps perdu (In Search of Lost Time)