tautology

/tɔːˈtɒlədʒi/ (bre, ipa) · /tɔːˈtɑːlədʒi/ (ame, ipa) · /tȯ-ˈtä-lə-jē How to pronounce tautology (audio)/ (ame, mw)

tautology — noun

  • tautologysingular
  • tautologiesplural

1. A way of expressing something where the writer or speaker restates a meaning wit

1.名詞B2
釋義

A way of expressing something where the writer or speaker restates a meaning with different words, making the longer phrase carry no extra information.

例句

The phrase 'free gift' is a common tautology because a gift is always given without payment.

collocation: 'a common tautology'

Indra crossed out 'past history' from the report and explained that it was an unnecessary tautology.

pattern: 'crossed out [phrase] as a tautology'

同義詞
  • redundancy

    broader term; any unnecessary repetition, not limited to same-meaning words

  • pleonasm

    more technical term used in linguistics for using more words than needed

  • repetition

    weaker and more general; does not specifically imply that meaning is duplicated

反義詞
  • concision

    the quality of expressing ideas in few words, opposite of tautology

文法句型

be + a + tautology

tautology + of + noun

用法筆記

When revising your own writing, check every adjective-noun pair: if the adjective's meaning is already part of the noun's definition (e.g., 'past history', 'future plans'), the phrase is likely a tautology.

常見錯誤

❌The book has a lot of tautology.
✅The book contains many tautologies.
💡When referring to multiple instances, use the countable plural form.

2. In logic and philosophy, a statement whose truth comes entirely from its own for

2.名詞C1
釋義

In logic and philosophy, a statement whose truth comes entirely from its own form rather than from any facts about the real world, so it cannot possibly be false.

例句

In propositional logic, the statement 'either it is raining or it is not raining' is a tautology.

classic logical tautology example

Mira's philosophy professor explained that 'A equals A' is the simplest tautology in any logical system.

同義詞
  • logical truth

    a statement true in all possible interpretations; a broader category that includes tautologies

  • analytic statement

    a statement true by definition alone, overlapping but not identical to tautology

反義詞

文法句型

be + a + tautology

reduce + to + a + tautology

用法筆記

This sense is specialised to logic and philosophy. Outside these fields, 'tautology' nearly always refers to the rhetorical sense (unnecessary repetition). Distinguish sense 2 from the rhetorical sense: a logical tautology is not a writing error but a formally valid truth.

常見錯誤

❌A tautology in logic is a mistake in writing.
✅In logic, a tautology is a statement that is always true by its form, not a writing error.
💡The two meanings of 'tautology' are distinct and should not be confused.