Literary criticism is comprised of an ongoing dialogue about art, specifically written works. The different perspectives on what literary art is and what it should do are sometimes referred to as schools of criticism.
The Critical Tradition: Classic Texts and Contemporary Trends is just one extensive source documenting critical commentary from as far back as Plato. The second edition of The Critical Tradition was a whopping 1655 pages long!
M.H. Abrams, in his widely cited work The Mirror and the Lamp, grouped the various critical perspectives into four simple categories:
Mimetic Theories: Evaluate art based on how accurately it “mirrors” reality.
Expressive Theories: Evaluate art based on how effectively the artist is at expressing him/her/hirself.
Pragmatic Theories: Evaluate art based on the impact it makes with the audience.
Objective Theories: Evaluate art based upon its empirical (observable, measurable) qualities.
For a full discussion of the many different school of criticism, see the Literary Theory and Schools of Criticism webpage at the Purdue OWL. A few of these schools of criticism are discussed in more detail below:
Structuralism maintains that literature should be viewed as a part of larger structures, such as storytelling, genre, and motif, to which it is related. Structuralism is based upon application of Ferdinand de Saussure’s linguistic model–which posits an arbitrary connection between words and what they signify–to other realms. Joseph Campbell’s classic The Hero with a Thousand Faces (which heavily influenced George Lucas while he was creating Star Wars) suggests that myths from around the world share similar structures, including archetypal heroes and their transformative journeys. Semiotics is similar to structuralism, but it is based on symbols rather than linguistic signs.