0 an explanation sb believes is true, although there is no proof -- théorie [ feminine ]
1 in science, an idea or set of ideas that attempt to explain how or why sth happens -- théorie [ feminine ]
the theory of Evolution la théorie de l’évolution
2 all the ideas or rules on which a subject is based -- théorie [ feminine ]
literary theory la théorie littéraire
3 an idea of the best way to do sth, which may be different from what happens in reality -- théorie [ feminine ]
4 an idea or explanation which has not yet been proved to be correct -- théorie
5 the main principles and ideas in an art, science etc as opposed to the practice of actually doing it -- théorie
I believe the theory is good, but it is not being applied particularly well.
So far, so good, as far as the theory goes.
The theory of comparative advantage teaches us that it is quite natural for a country to be ahead in certain sectors.
The theory is simpler than the practice.
My theory is as follows.
This is the out-dated 'shield' theory.