Grade Inflation: Myth or fact?

I think Alfie Kohn, the author of "The Dangerous Myth of Grade Inflation", makes a sound argument in saying that grade inflation really does not exist. He makes a lot of valid points as to why it is a myth. The fact that grade averages fluctuate every year does not mean the teachers are starting to be easier on students. It really depends on the student and the drive they have to do well in school. "Unfortunately, self-reports are notoriously unreliable, and the numbers become even more dubious when only a self-selected, and possibly unrepresentative, segment bothers to return the questionnaires. (One out of three failed to do so in 1993; no information is offered about the return rates in the earlier surveys.)" This quote is saying that there have been surveys done on grades students are receiving. And that one out of three failed to even return the surveys. Therefore, this makes grade inflation an irrelevant topic because if you are trying to figure out the grades of students, you need all of the data. What if that last report had all the bad grades people were looking for? The grades that were not "A's" and would disprove grade inflation? We will never know because the report was never returned. That is one flaw in the opponent's argument. There is not even enough evidence to support a grade inflation argument. Also, statistics show that grade averages fluctuate with every generation. "The proportion of A's and B's received by students: 58.5 percent in the '70s, 58.9 percent in the '80s, and 58.0 percent in the '90s. Even when Adelman looked at "highly selective" institutions, he again found very little change in average GPA over the decades." These statistics would also disprove the argument of "grade inflation." It shows that the teachers have nothing to do with grades students receive and that it depends on the generation. One generation might not think grades are important to their society, so their grades will be lower than the next generations'. But, that does not mean the grades inflated due to the grading system of teachers. Also, how does one even prove, with data, that the quality of work in students has gone down? Where would you find the data to prove that teachers are just giving students "A's" when they do not deserve it? The author even refers to this as a flaw in the grade inflation argument. "Maybe students aren't forced to take as many courses outside their primary areas of interest in which they didn't fare as well. Maybe struggling students are now able to withdraw from a course before a poor grade appears on their transcripts." Therefore, all of these "maybes" cannot prove that grade inflation is a real problem. No one can measure the quality of a student's work now, nor could they in previous years. Thus, grade inflation is a myth due to lack of evidence and data proving it otherwise.