To grade or not to grade

I've linked this article on grading. Or not grading. An English professor at Duke has decided to hand over the work of grading to her students by composing a simple list of tasks that students must complete to receive an "A", "B" etc. To determine whether the students have adequately completed the assignments, she allows small groups of students to grade one another.

This sounds fine for a standard English literature class where students are majors and well aware of the difference between adequate and work well done. But what about in other types of classes, such as folklore, where it make take students weeks to grasp the concept of what is and isn't folklore?

I welcome your thoughts here.