Theory often suggests to us something that is the opposite of practice. So you can either theorize something or you can do something. However, this is not a realistic dualism, since theorizing, or thinking, about something is part of almost every activity.

When we talk about literary theory, or a literary theory, we are designating a certain set of practices, or a certain vocabulary, with which we approach a text.

Why use literary theory?

Antitheory arguments have been made by many writers, most of whom disagree with what they see as theory's weakness: that is, it takes very different things and makes them seem the same by imposing an outside frame of reference. Thus everything is made to fit into the theory by transposing otherwise heterogeneous works into a common vocabulary or set of meanings.

When the use of theory becomes nothing more than imposition then it certainly loses its value. Ideally, however, theory (as a working vocabulary and set of practices) can show similarities between different things (things we'd never think of us as connected) without erasing their individuality. At its best, theory can show how localized instances (events, books, ideas) share similarities with things beyond that local context. Thus we can begin to get a sense of our world, not as a collection of individual and unrelated details, but as a huge network of interrelated things. Without theory, it would be impossible to see patterns or to consider change on anything but the very local scale.