rational

WOTD – 20 January 2009    

English

Alternative forms

Pronunciation

Etymology 1

From Old French rationel, rational, from Latin rationalis (“of or belonging to reason, rational, reasonable”), from ratio (“reason”)

Adjective

rational (comparative more rational, superlative most rational)

  1. Capable of reasoning.
    • 2001, Mark Sainsbury, chapter 1, Logical Forms — An Introduction to Philosophical Logic, edition 2nd, Blackwell Publishing, ISBN 978-0-63121-679-7, §7, page 32:
      How could a valid argument ever be persuasive? It is possible because we do not always acknowledge or take explicit note of all the logical consequences of our beliefs. If we did explicitly hold before our minds all the logical consequences of our beliefs, seeing them as consequences, we would already have accepted the conclusion of any valid argument whose premises we have accepted. Hence no valid argument could be persuasive. This is how things would be with a perfectly rational being. The utility of valid arguments is a monument to our frailty: to the fact that we are not completely rational beings.
    Man is a rational creature.
  2. Logically sound; not contradictory or otherwise absurd.
    His statements were quite rational.
  3. (of a person or personal characteristics) Healthy or balanced intellectually; exhibiting reasonableness.
    rational conduct
  4. (mathematics, arithmetic, number theory, not comparable) Of a number, capable of being expressed as the ratio of two integers.
    \tfrac{3}{4} is a rational number, but √2 is an irrational number.
  5. (mathematics, arithmetic, not comparable) Of an algebraic expression, capable of being expressed as the ratio of two polynomials.
Antonyms
Related terms
Terms etymologically related to rational
Translations
capable of reasoning
reasonable; not absurd
arithmetic: of a number
arithmetic: of an algebraic expression

Etymology 2

From Old French rational, from Medieval Latin rationale (“a pontifical stole, a pallium, an ornament worn over the chasuble”), neuter of Latin rationalis (“rational”), for which see the first etymology.

Noun

rational (plural rationals)

  1. (mathematics) A rational number: a number that can be expressed as the quotient of two integers.
    The quotient of two rationals is again a rational.
  2. A rational being.
    (Can we find and add a quotation of Young to this entry?)
Translations
rational number — see rational number

References

Anagrams

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Last modified on 20 April 2013, at 00:51