I think it is undeniable that clinics are not the place for a deep engagement with Rawls. That's equally true, of course, of a contracts course that focused on the details of modern contract doctrine -- even though some of Rawls' writing falls in the tradition of social contract thinking. As a general proposition, a deep engagement with philosophy requires ... a deep engagement with philosophy, and no course whose focus is on legal doctrine or legal practice will be likely to provide room for that kind of study.
Whether the same is true for other perspectives from beyond the law that students might need to study on their way to being lawyers may be more debatable. A clinic or a seminar focused on a public policy problem -- say, the treatment of homeless people in this country, or the involuntary hospitalization of the mentally ill -- may be an excellent place for students to encounter issues of sociology, psychology and public policy. These or other courses may also provide opportunities to study the interaction of law and economics. Certainly not every clinic will explore issues like these in depth (nor will every nonclinical seminar), but some can.
I'm more concerned, though, with Rawls and with moral philosophy. Clinics present many issues that call for moral judgments by lawyers and law students, but in the clinics -- as, I assume, in most lawyers' day-to-day practice -- these judgments are not made primarily by working through the views articulated by great philosophers. Presumably they're not made this way by most lawyers in practice either, nor by most people in their daily lives. Does the fact that clinic students are doing what practicing lawyers do amount to a defense?
Arguably not. One might respond that it is precisely because most people don't approach problems this way that our common solutions to problems are so flawed. Or one might say that while most people outside of schools don't address issues this way, it's the function of schools to provide learners with a foundation that they will be able to utilize, perhaps without even consciously being aware they are doing so, in the years to come.
I don't want to deny entirely the force of these responses. In particular, I do agree that school is a time to step back from what is immediate and seemingly self-evident, to challenge one's own thinking and develop judgments that are deeper than those with which one began. That function is probably a reason why the preparation for practice should not be all practice, since it is difficult -- not impossible, but difficult -- to challenge one's own thinking in the very midst of applying it.
But at the same time I don't think it is possible to show that the way people achieve mature morality is by academic study. Academic study does shed light, but much of it what it does is to induce confusion, and that confusion isn't likely to be fully resolved in any one course, or even any series of courses. Meanwhile, growth as a moral person may proceed on quite different paths -- through empathetic response to suffering, for example. Growth as a social thinker may be the result as much of growth in one's personal relationships as of growth in one's academic mastery of the relevant issues.
So in the end I don't think the fact that clinics are not the place to learn Rawls, or more generally the place to explore extra-disciplinary perspectives on law, should dissuade us from thinking -- as the current critique of law schools urges -- about how to make our schools more practice-oriented. And when we turn to that task, it seems to me that the claim of clinics (and other skills courses) is a powerful one: to learn to practice, one must practice.