in theory

idiom

Definition of in theory

1 —used to say what should happen or be true if a theory is correct

2 —used to say that something seems to be true or possible as an idea but may not actually be true or possible

I agree with you in theory, but realistically I don't think we have the time to do that.

theory play

: a plausible or scientifically acceptable general principle or body of principles offered to explain phenomena
: a belief, policy, or procedure proposed or followed as the basis of action
: an ideal or hypothetical set of facts, principles, or circumstances