Bauerschmidt notes that Aquinas frequently argues, especially when speaking of the incarnation, not for “proof” of doctrine but for its “fittingness.” Reason has the role of “manifesting how [the incarnation] fits together (convenire means literally ‘to come together’) with other things that Christians hold true about God.”

Perhaps this can be seen as an aesthetic criterion: Theological arguments are not deductive proofs, but efforts to display the harmony of sacred teaching.