The relation between faith and reason is the question of whether religious belief can be established, supported or overturned by argument — and what follows for belief if it cannot.

The positions

Three broad answers recur. Faith and reason may be in conflict, so that accepting one means limiting the other. They may be compatible, with reason establishing some claims and revelation supplying what reason cannot reach. Or they may be independent, answering different questions and unable to contradict each other.

Aquinas's synthesis

Thomas Aquinas built the most influential compatibilist account in the thirteenth century, after Aristotle's works re-entered Latin Europe through Arabic commentators including Averroes and Avicenna. Reason can demonstrate that God exists — that is what the Five Ways attempt — while doctrines such as the Trinity are known only through revelation. Grace perfects nature rather than replacing it, so philosophy and theology cannot ultimately conflict.

Anselm had earlier described the program as faith seeking understanding: belief comes first and reason explores what is already held.

The dissenting lines

Tertullian's question about what Athens has to do with Jerusalem marks the oldest objection: the content of faith is not the kind of thing argument reaches. Kierkegaard gave the sharpest modern version, arguing that faith involves a leap that no argument can perform for you, and that treating belief as the conclusion of a proof misunderstands the commitment it is.

From the other direction, evidentialism holds that beliefs should be proportioned to evidence and that religious belief fails the standard. Reformed epistemology replies that belief in God may be properly basic — held without inference, in the way belief in other minds is — which shifts the dispute to what a rational belief must rest on.

The question connects to epistemology, since both sides need an account of what justifies a belief.