Classes like this would be graded "on a curve". In a 2nd-year PhD level theory class I'd assume the default grade is an A. The point of classes at that level i

Classes like this would be graded "on a curve". In a 2nd-year PhD level theory class I'd assume the default grade is an A. The point of classes at that level is to provide background and skills for research, and the teachers trust the students to be doing the work to get what they need out of a class. Some students will really want to master the material, some will only feel they need some familiarity, and the test as to whether they got what they need will come in their PhD research over the next few years, not in an exam. In a course with "real" grades, it still may well be that 60% is an A; I've had classes like that. In that case, it's just divided so that the top 20% get an A, next 30% get a B, and so on.