in theory
- idiom
- /ɪn ˈθɪəri/
- And I think that that is great in theory but not in practice.
- at least in theory
- possible in theory
- in theory and practice
This in theory is such a good idea.
- This in theory is such a good idea.
- It's something that your enemies could, in theory, figure out on their own.
- And these relay attacks work in theory, but you don't see them in practice.
- You could, in theory, if we, like, changed our names.
- I mean, in theory, what could go wrong?
- And the answer to this, in theory again, is yes.
- But in, but in theory, in theory, embeddings isn't that complicated.
- So I've stolen Zoe's Ray Bans, which in theory is great.
Examples
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In theory, it's possible for James Hunt to catch you.
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In theory, we could solve the problem with a simple adjustment.
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Well that actually sounds OK in theory, but how can we know that?
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When you go along, you could, in theory, bet all of your money.
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And sure, in theory, anybody can learn to change.
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So if it is at least good in theory, why is it bad in practice?
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Still, it was one thing to know it in theory and another thing to see it in practice.
Fiction book (1991) -
No, the protocol, in theory, is sound.
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In theory, yes, but in practice it's a difficult concept to sustain.
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In theory, everyone's equal... and has the right to pursue whatever makes them happy.
Synonyms
Something is true by the exact rules or facts, not by how people usually think
An idea that seems right but is not always true in real life
It is true in writing or in theory but not always in real life
People agree to it in general but details are not decided
In theory or for calculation, it is not actually real
How Theoretical
Surface Forms
Morphology
The meaning 'according to principles' is directly and compositionally derived from 'in' (within/according to) + 'theory' (a set of ideas or principles). This preposition + noun pattern is cross-linguistically common (e.g. Spanish 'en teoría', French 'en théorie'), so a B1 learner who knows both words will readily infer the MWE meaning.
Etymology
In theory comes from the picture of a plan or idea called a theory, like a design drawn on paper that should work. So when you say in theory you mean 'according to the idea or rules', even if it may not work in real life.