Theory vs Certainly - What's the difference?

theory | certainly |

As a noun theory

is mental conception; reflection, consideration.

As an adverb certainly is

in a way which is certain; with certainty.




  • (obsolete) Mental conception; reflection, consideration.
  • * 1646 , (Thomas Browne), Pseudodoxia Epidemica , VII.19:
  • As they encrease the hatred of vice in some, so doe they enlarge the theory of wickednesse in all.
  • (sciences) A coherent statement or set of ideas that explains observed facts or phenomena, or which sets out the laws and principles of something known or observed; a hypothesis confirmed by observation, experiment etc.
  • * 2002 , Duncan Steel, The Guardian , 23 May 2002:
  • It was only when Einstein's theory' of relativity was published in 1915 that physicists could show that Mercury's "anomaly" was actually because Newton's gravitational ' theory was incomplete.
  • * 2003 , (Bill Bryson), A Short History of Nearly Everything , BCA, p. 118:
  • The world would need additional decades [...] before the Big Bang would begin to move from interesting idea to established theory .
  • * 2009 , (Richard Dawkins), The Greatest Show On Earth: The Evidence for Evolution , Bantam, p. 10:
  • Scientists and creationists are understanding the word "theory'" in two very different senses. Evolution is a '''theory''' in the same sense as the heliocentric '''theory'''. In neither case should the word "only" be used, as in "only a ' theory ".
  • * {{quote-magazine, date=2012-01
  • , author=Michael Riordan , title=Tackling Infinity , volume=100, issue=1, page=86 , magazine= citation , passage=Some of the most beautiful and thus appealing physical theories', including quantum electrodynamics and quantum gravity, have been dogged for decades by infinities that erupt when theorists try to prod their calculations into new domains. Getting rid of these nagging infinities has probably occupied far more effort than was spent in originating the ' theories .}}
  • (uncountable) The underlying principles or methods of a given technical skill, art etc., as opposed to its practice.
  • * 1990 , Tony Bennett, Outside Literature , p. 139:
  • Does this mean, then, that there can be no such thing as a theory of literature?
  • * 1998 , Elizabeth Souritz, The Great History of Russian Ballet :
  • Lopukhov wrote a number of books and articles on ballet theory , as well as his memoirs.
  • (mathematics) A field of study attempting to exhaustively describe a particular class of constructs.
  • Knot theory classifies the mappings of a circle into 3-space.
  • A hypothesis or conjecture.
  • * 1999 , Wes DeMott, Vapors :
  • It's just a theory I have, and I wonder if women would agree. But don't men say a lot about themselves when a short-skirted woman slides out of a car or chair?
  • * 2003 , Sean Coughlan, The Guardian , 21 Jun 2003:
  • The theory is that by stripping costs to the bone, they are able to offer ludicrously low fares.
  • (countable, logic) A set of axioms together with all statements derivable from them. Equivalently, a formal language plus a set of axioms (from which can then be derived theorems).
  • A theory is consistent if it has a model.

    Usage notes

    In scientific discourse, the sense “unproven conjecture” is discouraged (with hypothesis or conjecture preferred), due to unintentional ambiguity and intentional equivocation with the sense “well-developed statement or structure”.


    * See also


    * (in logic) formal system


    * (in logic) axioms

    Derived terms

    * acoustic theory * algorithmic information theory * antenna theory * atomic theory * catastrophe theory * category theory * cell theory * chaos theory * circuit theory * complexity theory * computation theory * control theory * critical theory * decision theory * domino theory * extreme value theory * game theory * giant impact theory * graph theory * group theory * in theory * information theory * kinetic theory of gases * knot theory * literary theory * music theory * number theory * opponent-process theory * phlogiston theory * probability theory * proof theory * quantum field theory * rational choice theory * set theory * signal theory * social theory * systems theory * theory of gravity * theory of relativity * theory of truth * Theory X * Theory Y * type theory * value theory * virtue theory

    See also

    * axiom * postulate * proposition Check translations




    (en adverb)
  • In a way which is certain; with certainty.
  • *, I.iii.2.2:
  • *:he verily thought he had young live frogs in his belly, qui vivebant ex alimento suo , that lived by his nourishment, and was so certainly persuaded of it, that for many years following he could not be rectified in his conceit.
  • Without doubt, surely.
  • :
  • :
  • :
  • *
  • *:So this was my future home, I thought! Certainly it made a brave picture. I had seen similar ones fired-in on many a Heidelberg stein. Backed by towering hills,a sky of palest Gobelin flecked with fat, fleecy little clouds, it in truth looked a dear little city; the city of one's dreams.
  • *{{quote-magazine, date=2013-06-07, author=(Gary Younge)
  • , volume=188, issue=26, page=18, magazine=(The Guardian Weekly) , title= Hypocrisy lies at heart of Manning prosecution , passage=WikiLeaks did not cause these uprisings but it certainly informed them. The dispatches revealed details of corruption and kleptocracy that many Tunisians suspected, but could not prove, and would cite as they took to the streets.}}
  • An emphatic affirmative answer; of course.
  • :
  • Synonyms

    * absolutely, beyond doubt, indubitably, sure thing, undoubtedly, wis, without a doubt

    Coordinate terms

    * maybe, possibly, arguably, questionably, probably, perhaps

    Derived terms

    * most certainly


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