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Philosopher

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Thomas Aquinas

1225–1274 · Scholasticism · Medieval

Thomas Aquinas, a Dominican born near Aquino in 1225, died in 1274, built the most influential synthesis of Christian theology and Aristotelian philosophy in the Latin Middle Ages. He studied at Naples, Paris, and Cologne, disputed, and wrote commentaries as well as the great summaries. The Summa Theologiae is a teaching book in questions, objections, replies, and answers to objections.

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A sentence pulled from it is usually one step. He argues that God's existence is not self-evident to us and can be shown in five ways from features of the world. He defines law as an ordinance of reason for the common good, made by the one who has care of the community, and promulgated.

Natural law is his bridge between practical reason and moral order. He read Aristotle in Latin versions shaped by Islamic and Jewish philosophers, and he argues with Averroes, Avicenna, and Maimonides by name. He is not a plaster saint who never states the case against himself. The objections come first. Later philosophy will contest the premises, especially about change and cause.

Start here

Summa Theologiae, first part, question 2, then the first part of the second part, question 90

Question 2 is the five ways, objections included. Question 90 is the definition of law. Both show the article form, which is how he thinks.

Quotations

“Law is an ordinance of reason for the common good, made by one who has care of the community, and promulgated.”

Thomas Aquinas · Scholasticism

justicesocietypower
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“Grace does not destroy nature, but perfects it, so that natural reason should minister to faith as the natural bent of the will ministers to charity.”

Thomas Aquinas · Scholasticism

knowledgevirtue
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“Justice is a habit whereby a man renders to each one his due by a constant and perpetual will.”

Thomas Aquinas · Scholasticism

justicevirtueethics
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Meaning & application

Key ideas

  • Five ways

    God's existence is not self-evident to us, but can be argued from change, cause, contingency, degrees, and directedness.

  • Definition of law

    Law is an ordinance of reason for the common good, by the community's caretaker, and it must be promulgated.

  • Natural law

    Practical reason shares in an eternal order, so some moral precepts are not merely local commands.

  • Grace and nature

    Nature is not cancelled by grace, and philosophical argument has a real place inside theology.

Major works

  • Summa Theologiae (1265–1274)

    Unfinished teaching summary. The five ways and the treatise on law are the usual doors.

  • Summa contra Gentiles (c. 1259–1265)

    A more continuous argument about faith and reason, written before the Summa Theologiae.

  • Aristotle commentaries (1260s–1270s)

    Close readings that show how much of his thought is commentary rather than free-standing theses.

Influences

Influenced

Common misreadings

  • The sentence that there are five ways is itself the proof.
  • Any enforced command counts as law in his sense, even if it misses reason or the common good.

Famous lines Thomas Aquinas never said

None of the lines this library files for Thomas Aquinas is marked Questionable or Misattributed. That is only a fact about these cards. It is not a certificate that every popular sentence is theirs.

FAQ

What is the best book to start with?

Summa Theologiae, first part, question 2, then the first part of the second part, question 90 Question 2 is the five ways, objections included. Question 90 is the definition of law. Both show the article form, which is how he thinks.

What is the most famous quote?

This library does not measure fame, and it does not rank lines by how often they are shared. The first line it files for Thomas Aquinas that is not marked Questionable or Misattributed is “Law is an ordinance of reason for the common good, made by one who has care of the community, and promulgated.” (Summa Theologiae I–II, question 90, article 4, Paraphrase or translation).

What is the most misquoted line?

None of the lines this library files for Thomas Aquinas is marked Misattributed or Questionable. That is a fact about these cards, not a certificate that every popular sentence is theirs.

What is one key idea, in a sentence?

Five ways: God's existence is not self-evident to us, but can be argued from change, cause, contingency, degrees, and directedness.