Thomas Aquinas

Life and ideas

Thomas Aquinas, an Italian Dominican friar, taught at the University of Paris and in Italy and wrote the Summa Theologiae, an enormous systematic account of Christian thought. In the part known as the Treatise on Law, he defines law as an ordinance of reason for the common good, made and promulgated by whoever has care of the community. He distinguishes four kinds: the eternal law, God's plan for the universe; the natural law, the part of it that human reason can discover, whose first precept is to do good and avoid evil; human law, made by rulers to apply natural law to particular circumstances; and divine law, revealed in scripture. A human law that conflicts with natural law is, he says, not truly law but a corruption of law, though it may sometimes have to be obeyed to avoid scandal or disorder. His theory is the classic form of natural law thinking.