The graph is from an analysis by Stuart Rojstaczer & Christopher Healy which looks at college/university level grades at 200 US institutions of higher education (via Catherine Rampel, via via Mike the Mad and Isis).
For some very odd reason nobody seems to be hypothesizing that the demographic of undergraduates that experience the greatest uptick in A grades and the greatest reduction of C grades was simply smarter than prior generations.
That should be the null hypothesis, right? I mean, it is pretty far fetched of Ms. Rampell and Dr. Isis to blame this on professor's motivation to keep kids out of 'nam since that should have affected the D and F grades, no?
Mike the Mad wants to blame it on graduate school admittance and the competition for limited slots....but can this really explain the late60s-early70s trends?
More likely to explain this is the incredible self-indulgence and self-righteousness of the late Boomers and the overweening generational meme that traditional "standards" were arbitrary constructs and have no bearing on proper evaluation. I'm okay, you're okay and all that nonsense. and above all else, the sense of universal, personal entitlement.
and what do you know, as soon as the children of these people start hitting the Universities, up go the grades again.