Consider the typical way we grade students in a course. We give a number of assignments. We grade each. Then we average those grades to get a course grade. That course grade is then taken by various outside agents - employers, grad schools, etc. - to be a measure of accomplishment. But there is one very obvious irrationality in this system. Consider two students: student 1 has had the benefit of excellent prior training at, say, a top private HS. 2 has gone to much weaker schools. Maybe 1 has already had some philosophy and certainly has good training in writing papers. 2 does not. Thus, on the first assignment, 1 ends up with a much better grade than 2 because the paper is just plain better. Over the course of the term, however, 2 improves at a vastly higher rate and by the end of the term they are doing work at the same level. Even those professors who include "improvement" as a factor in the final grade are likely to give 1 a higher grade than 2. (Let's assume that 1 does better on all assignments up to the final one, but stipulate that one's assessment at the end of the course is that they are now producing work of equal quality.) ... that will have unjust effects on their future. I mean "unjust" in the most straightforwardly meritocratic sense. Even if we ignore all other factors, the uptake of a B for one student and an A for another is that the latter is "better" at the course material, or at least did better in the course. But that is just false if they both end up with equal competence and understanding at the end.
I think Mark is on to something here: I've often favored mastery-based grading (what can the student do) over task-based grading (what did the student do). For one, it focuses students' attention at the right things. Too often students approach their coursework largely in terms of getting good grades on particular assignments and tests rather than on mastering the knowledge or skills involved. Of course, if we design the assignments and tasks well, we'll be measuring student knowledge or skill. Still, task-based grading seems to encourage students to take a very short-term perspective on their work. Second, mastery-based grading is more 'real world.' In non-academic settings, people will expect you to be able to design that building, produce that sales plan, perform that surgery. You don't 'get credit' from your employer for performing tasks at less than a mastery level.
The challenge is this: How could we introduce master-based grading into philosophy classes? (In the comments at NewAPPS, Dustin Locke describes a possible way to do so.) And I would expect many students, accustomed to the task-based approach, will rebel. Has anyone out there tried to grade more based on mastery than discrete task performance, and if so, how?