Aquinas’s conception of faith has been taken to involve believing in a way that is expressly out of keeping with the evidence. Rather than being produced by evidence, the confidence involved in faith is a product of the will’s decision. This causes Aquinas’s conception of faith to look flagrantly irrational. Herein, I offer an interpretation of Aquinas’s position on faith that has not been previously proposed. I point out that Aquinas responds to the threat of faith’s irrationality by explicitly maintaining that one may reasonably believe by faith because of an instinct to believe. I go on to point out other instances in which instincts amount to legitimate epistemic grounds for Aquinas. Given that this dimension of Aquinas’s thought is not well developed, I close by introducing some extensions of it in the work of John Henry Newman as well as points of contrast.