Grammar fix
in theory
in theory
Used to say that something should be possible or true according to an idea, although reality may be different.
expression
How oftenVery common
LevelB1
Used inSpeech & writing
Hear it in context
Notice where the phrase sounds natural.
In theory, the new timetable should give us more time for lunch.
In theory, public transport should reduce traffic, but in my city it is often too crowded to be comfortable.
Fix the pattern
One small grammar move makes it sound right.
Not: On theory, this should save money.
Say: In theory, this should save money.
Use the fixed phrase 'in theory', not 'on theory'.
Don't confuse it
Other ways to say it
Should work, but not yet proven
How formalConversationalFormal
on paperSomething looks workable before real conditions are taken into account.
in theoryYou're here · Something should work, though reality may be different.
in principleThe basic idea allows it, though practical obstacles may remain.