Grade Inflation Might Be Grade Redistribution

Bryan Caplan has a great post arguing that teachers who favor redistribution of income should also favor redistribution of grades, i.e., pity grading.

To me, this reveals a basic inconsistency in egalitarian philosophy. If you
assign grades based on merit, and merit depends on performance unadjusted for
opportunity, then why shouldn't the same principle hold for income and wealth?
Just because you feel sorry for someone, why does that entitle them to a share
of the riches of the more successful? And if you do not adjust for unequal
opportunities when you grade, why should you adjust for unequal opportunities
when you contemplate redistribution?

In a later post he states:

Complete equalization of grades and income destroys the value of both. But moderate redistribution destroys the value of neither. The U.S. income tax has not turned America into Haiti, and basing 5% of our grades on pity rather than merit would not wreck our educational system.

I think that grade inflation is partially explained by 5% of grades being based on pity. A professor who wanted to follow the 5% pity strategy would determine what the typical standards were and distort them slightly by increasing all grades below A. Unlike income redistribution, pity grading doesn't require anyone's nominal grade to be reduced.

Pity grading might also explain why grades in the humanities are higher than grades in engineering. On average, humanities professors favor more income redistribution, so as Bryan (I'm outing him as a flamboyant, one-name personality like Madonna) points out, it makes sense that they would favor more grade redistribution.