According to Aquinas, theologians use the conceptual tools furnished by philosophy to elucidate the contents of revelation. Just like philosophers, theologians make arguments, and their arguments appeal to common standards of logic and rigor, even though they also draw on theology’s own unique (revealed) axioms and sources of evidence (Summa Theologiae 1.1.1). Philosophical arguments cannot prove the foundational truths of revelation, according to Aquinas, but at the same time, revelation and reason cannot conflict. (That God exists is a truth of reason, not revelation, for Aquinas—see Summa Theologiae 1.2.2, reply to obj. 1.) Theologians can therefore use common standards of philosophical reasoning to answer any putative objections to their theological claims, by showing that any alleged conflict is only apparent. So, for example, even though it is not possible to establish that God is triune by means of philosophical arguments, it is possible to use philosophical arguments in a defensive mode, to answer objections alleging that the doctrine of the trinity is logically incoherent. When arguing with other Christians, theologians can appeal to revelation to support their claims. When arguing with opponents who do not accept revelation, they cannot (Summa Theologiae 1.1.8). Yet this restriction is not really a disciplinary maxim designed to oppose philosophy to theology, but a pragmatic admission that one cannot successfully persuade opponents by appealing to premises they deny.