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Philosopher

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William of Ockham

c. 1287–1347 · Nominalism · Medieval

William of Ockham was an English Franciscan, born around 1287 and dead around 1347, and a logician of unusual severity. He worked in Oxford and then, after a clash with the papacy over Franciscan poverty, wrote much of his later work in exile under imperial protection. His logic and theology are cautious about multiplying entities.

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Universals, on his account, are not extra things in the world alongside individuals. He repeatedly says that plurality is not to be posited without necessity. The neat Latin tag that entities are not to be multiplied beyond necessity, and the neat English that matches it, are later capsules, not a sentence he is known to have written.

The habit is his. The slogan is the textbook's. He also wrote on church power and on the relation of spiritual to secular authority, work that matters for political thought and almost never appears on a quotation card. Short safe English from his technical Latin is scarce. This library keeps the famous razor, marks it Questionable, and does not invent a fourth sentence to fill the page.

The entities slogan stays Questionable. Three placed claims are included: the parsimony formula in Summa Logicae I.12, the definition of a universal in I.14, and the conclusion of Ordinatio I, distinction 2, question 8. A fifth slogan was not added.

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A scholarly introduction to his logic that quotes his own formulations about plurality, beside the Summa of Logic in translation if one is available

The slogan is the obstacle. His wording is technical and plural. Seeing the difference is the lesson.

Quotations

Key ideas

  • Parsimony

    Do not posit more entities than an explanation needs, which is a rule of theory rather than a claim that the world is simple.

  • Nominalism

    Universals are not extra entities in things, and the real habit of the razor lives in that caution.

  • The slogan is later

    The famous sentence about not multiplying entities is a later capsule of several technical wordings.

Major works

  • Summa of Logic (c. 1323)

    His major logical work, where the caution about extra entities is practised rather than sloganised.

  • Commentary on the Sentences (c. 1317–1319)

    Early theological work from the Oxford years, highly technical.

  • Political writings (1330s–1340s)

    Arguments about papal power and poverty, important and rarely quotable in a sentence.

Influences

Influenced

  • Later nominalism
  • Luther

Common misreadings

  • He wrote the English sentence about entities, or the matching Latin tag.
  • The razor proves the simplest story true, rather than forbidding idle extras.

Famous lines William of Ockham never said

Misattributed means the library does not treat the sentence as theirs. Questionable means there is a real doubt, which is not the same as a proof they never wrote it. Both are listed here.

  • Questionable

    “Entities are not to be multiplied beyond necessity.”

    Ockham repeatedly insists that plurality is not to be posited without necessity, in several wordings. The neat English sentence, and the Latin tag that matches it, are later capsules, not a sentence he is known to have written. The badge stays Questionable.

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FAQ

What is the best book to start with?

A scholarly introduction to his logic that quotes his own formulations about plurality, beside the Summa of Logic in translation if one is available The slogan is the obstacle. His wording is technical and plural. Seeing the difference is the lesson.

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 William of Ockham that is not marked Questionable or Misattributed is “It is futile to do with more what can be done with fewer.” (Summa Logicae, part I, chapter 12, the parsimony formula in his Latin, in English, Paraphrase or translation).

What is the most misquoted line?

No line filed for William of Ockham is marked Misattributed. The nearest doubt is Questionable, which is not the same thing: “Entities are not to be multiplied beyond necessity.” Ockham repeatedly insists that plurality is not to be posited without necessity, in several wordings. The neat English sentence, and the Latin tag that matches it, are later capsules, not a sentence he is known to have written. The badge stays Questionable.

What is one key idea, in a sentence?

Parsimony: Do not posit more entities than an explanation needs, which is a rule of theory rather than a claim that the world is simple.