Thomas Aquinas

Lore & Background

The source identifies Thomas Aquinas as the medieval Catholic theologian who interpreted Aristotle in developing classical natural law theory. According to the source, Aristotelian natural law theory originates in Aristotle's teleological view of nature and ethics, which asserted that what is good for man can be determined, by reason, from the functions of man. Aquinas built upon this foundation. The source notes that classical natural law was hugely influential in the medieval development of canon law, international law, and political philosophy, later resulting in the social contract theory as developed by Rousseau and Locke. By the Age of Enlightenment, natural law philosophy had largely fallen out of favor among political and legal philosophers, with major criticisms of Thomist natural law contained in the empiricist, social contractarian, and utilitarian ideals of Hume, Hobbes, and Bentham. The source also mentions that twentieth-century philosophy saw a resurgence of interest in natural law, specifically the new natural law of John Finnis, who offered a reinterpretation of Aristotle and Aquinas.

Reader's Guide

Thomas Aquinas's significance in jurisprudence lies in his development of classical natural law theory. The source states that classical natural law theory is associated with the legal maxim 'lex injustia non est lex' (unjust law is not law), either as a criteria of validity for law (per classical natural law theory) or as relating to theoretical notions of justice and the proper purpose of law (per 'new natural law' theory). Aquinas's work interpreted Aristotle's teleological view of nature and ethics, which held that what is good for man can be determined by reason from the functions of man. The source notes that Aquinas's classical natural law was hugely influential in medieval canon law, international law, and political philosophy. Contemporary secular jurists continue to invoke naturalist arguments in asserting the existence of legally-recognized human rights, limitations to state power, and the ability of the courts to review the decisions of other bodies of state.

Did You Know?

• Thomas Aquinas interpreted Aristotle in developing classical natural law theory.
• Classical natural law theory is associated with the legal maxim 'lex injustia non est lex' (unjust law is not law).
• Aquinas's natural law philosophy was hugely influential in the medieval development of canon law, international law, and political philosophy.
• Major criticisms of Thomist natural law came from empiricist, social contractarian, and utilitarian thinkers including Hume, Hobbes, and Bentham.
• Twentieth-century philosopher John Finnis offered a reinterpretation of Aristotle and Aquinas known as new natural law.