The underlying intuition to first condition this question is that what is picked out by the word “philosophy” is basically the same as what is picked out by 'theory.' 'Theory' is whatever part of a discipline that reflects on the tools that discipline deploys to do its work. Thus, for example, 'theory' is what is being done when a sociologist reflects on what is picked out by 'society' or 'group' or an anthropologist on 'culture' or 'ritual.' Almost every discipline these days has its own theory department, and no longer farms out the work to philosophy. (This didn’t used to be the case.) This has been a problem for philosophy, insofar as it has been harder for it to justify itself, but just insofar as it’s a problem for philosophy, it is—often covertly to those independent disciplines asking philosophy to justify itself—also a problem for the disciplinary theory-heads. The reason for this is that the experience of philosophy for 2500 years has been with abstract concepts and their relationships to each other. It has dabbled in concrete stuff from time to time, but every time it gets on a roll, the group of people in charge of the inquiry become full of themselves and secede from the union (a typical origins-story about disciplines from philosophy’s point of view). Without a doubt, every discipline has its own special problems that it needs its own special tools for, and for the most part it is best that a discipline make and improve its own tools (though outright stealing works, too). However, when it comes to seeing the relationship between those special tools and the special tools that other people are using, no one has any special province. The closest you can get is philosophy—that group of people with 2500 years of experience dealing with that kind of thing.
If you start with this understanding of 'philosophy' and 'theory,' the relationship between literary criticism and literary theory becomes a little clearer. It’s really the relationship between practical criticism of literary texts and theoretical reflection on the tools you use in those practical contexts. When you read Hawthorne through the lens of Freudian psychoanalysis or Melville through the lens of Derridean deconstruction, you’re doing practical criticism when the primary goal of your train of thought is reading Hawthorne or Melville. If you’re trying to make a comment on psychoanalytic theory or deconstruction using whatever insight you may have pulled from reading Hawthorne or Melville, the comment itself is theory and besides the point of reading Hawthorne or Melville. Getting the theory right is a different context than using it to read other texts. It’s important to understand this. In the act of writing, one can attempt to do many things. But to know you’re doing many things, or to just do one thing and not those other things, one needs to see how to differentiate between different activities. And in the terms I’ve laid out, 'getting theory right' means doing philosophy, which means attending to the problems generated in a different disciplinary sector than that of getting the literary text right. . . .