Revealed Reasons

It is a bit of a commonplace among Christians that there are two sources of truth, reason and revelation. These two sources are normally considered mutually exclusive, that is, nothing that is revealed by one is revealed by the other. However, Thomas Aquinas believed that these two sources were not, in fact, mutually exclusive. In fact, a number of the most important truths of reason, the existence of God and natural law, were deliberately revealed by God.

Thomas Aquinas's reasons were both Biblical, philosophical and traditional. Biblically, he was concerned with several passages. For the existence of God, the most important was Psalm 14:1, "The fool says in his heart, there is no God". If anyone who does not believe in God is a fool, anyone who is rational must believe in God. For natural law, he was concerned with Romans 2:14-15, "(for when Gentiles that have not the law do by nature the things of the law, these, not having the law, are the law unto themselves (15) in that they show the work of the law written in their hearts, their conscience bearing witness therewith, and their thoughts one with another accusing or else excusing [them])" Without explicit revelation, the gentiles had access to the law by nature.

His philosophical concerns were that many philosophers had written proofs of the existence of God and natural law, especially Aristotle, that he believed were strong arguments and, were they not from reason, would have been extremely lucky guesses. His concerns from tradition were that other great theologians had attempted proofs for the existence of God, especially Augustine and Anselm (though he didn't think Anselm's proof worked). If it were impossible to gain such a truth, great theologians wouldn't search for it.

Aquinas's conclusion, then, is that God revealed to humanity things that were accessible to human reason alone. He believed that it made sense for God to do this. First, it made sense because not all human beings are philosophers or have the leisure to persue philosophy. While it may be true that the existence of God or the content of the natural law may be accessible to people after long study, not everyone has the capacity or the time for that study. Second, sin corrupts the reason, especially in matters of God and morality. When people rebel from God or desire pleasure, they are often unable or unwilling to reason properly. As such, though the existence of God and natural law may be demonstrable to a virtuous, philosophical mind with leisure, it is not available to everyone. Therefore, having the existence of God and the natural law revealed would make them more accessible to everybody.

This raises an interesting problem in cases of morality and the relationship of church and state. For Catholics and other Christians who support Aquinas' argument, the teaching of natural law are revealed by God, but are also accessible to reason. This means that attempts to promote the natural law (basically, Commandments IV-X) are not necessarily attempts to impose religious views. Catholics are encouraged to understand the natural, rational reasons behind the Church's positions on issues such as abortion or gay marriage and use these in debate. When a Catholic or other Christian does so, they enter these debates with reasons that are appropriate to public debate.

Aquinas's position on the relationship between reason and revelation in the existence of God and natural law provides an opportunity for Christians to do natural theology and ethics without feeling that they are somehow undermining the revealed character of these topics. God has written these things both in Scripture and in our hearts.