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Thomas Aquinas

Monstrance

The rediscovery of Aristotle's philosophical works renewed the force of reason within the Christian faith. Although Aquinas (1225–1274) is said to have "baptized" Aristotle, the influence clearly ran the other way, giving rise to the glories of the High Middle Ages. One of the chief expositors of the natural law theory, Aquinas also authored some of the most widely-cited rational arguments in proof of the existence of God.

God's Existence Can Be Known by Reason

The "Five Ways" of proving God's existence are the most famous in all philosophical literature, yet they are merely sketches, rather than developed proofs. (Note: "Objections" express the opposite of Aquinas' views.)

Eternal, Natural, Human, and Divine Law

Eternal Law is the Divine Reason. We participate in this law by way of reason, which gives us the ability to distinguish between good and evil. Based on this understanding, we enact the written laws of government.

The Central Teachings of the Natural Law

The most general precepts of the natural law are self-evident and so cannot be forgotten, namely, that we should preserve our existence, propagate our species, and live peaceably in society under the light of reason.

Human Laws Must Reflect the Law of Nature

Human law, if it is to be just by nature, must seek the common good of all. Human law should encourage the practice of virtue among the people. Just laws bind us in conscience, but unjust laws are not laws at all.