We should certainly give this much to Michael Gove. He deserves an A* for novelty. In years past, three things became utterly predictable about the August exam results season. The number of pass grades and better invariably broke new records. The newspapers would mark the release of GCSE and A-level results by reserving a lot of space for pictures of happy students (pretty teenage girls being favoured by news editors over nerdy teenage boys) hugging, whooping and generally celebrating the contents of their envelopes. And whoever was education secretary, though always less attractive and sometimes less brainy than the celebrating girls, would be sure to be grinning all over our television screens, claiming the results as a great vindication for him or herself and the government's policies.

This Mr Gove has never done during his time as education secretary. He always said that he would not greet exam results as his Labour predecessors did by patting himself on the back and saying: "What a good boy am I." How could he, after all? It would have been rather hypocritical when his has been a strident voice alleging that the value of GCSEs and A-levels has been corroded by the "dumbing down" of exams and the over-generous awarding of grades.

So in his first two Augusts as education secretary, when records continued to be broken, Mr Gove did not look terribly content. He has had to wait until now to find something to celebrate about the exam results season. "Brilliant!" he cried as GCSE grades fell for the first time in the exams' 24 years of existence. "More children are failing." Well, all right, he didn't quite say that, at least not out loud. But he looked pretty satisfied to me and, given all that he has said in the past about making exams tougher, he ought to be happy about that and the dip the previous week in A-level grades.

He has had to stress, of course, that he put no direct pressure on Ofqual, the regulator, to force down grades. The regulator has in turn denied that there was any heavy breathing down its neck from the education secretary. Ofqual's boss assured viewers of Newsnight that she took her "independence" so seriously that she had never had a single conversation with Mr Gove about grades. Some people have found this hard to believe, but I am inclined to take both him and her at their word. The education secretary would not need invite her in for a coffee for the head of Ofqual to know that he wants to make it harder to achieve pass and top grades. He would not need to do so because he has swished the cane of "academic rigour" in countless interviews and speeches in which he has made it abundantly clear that this is what he wants to happen.

Whether or not Mr Gove has been leaning on Ofqual is, in any case, a second-order issue. One question that matters more is whether or not he is right to want to make it harder to achieve passing grades. There are reasons to share some of his concerns about grade inflation. Between 1988 and 2011, GCSE A grades rose by a factor of almost three while there was an increase of more than 60% in the proportion of Cs awarded.

Educational professionals defend this surge by arguing that it reflects more money being spent on schools, better teaching and improvements in the aptitude and application of pupils. I go along with that some of the way, but not all of the way. Independent, international studies of educational attainment suggest that not all of the rise in grades can be related to genuine improvements. The comments of universities and employers about numeracy and literacy skills should also make us sceptical that this long period of uninterrupted grade rises can be fully justified. If the trend continued indefinitely, we would eventually get to the stage where virtually no one would fail an exam and ever-ballooning numbers would achieve the highest grades.

I am going to use a rude word: discrimination. Exams are supposed to discriminate. They are there to tell those who take them, as well as colleges, universities and potential future employers, what someone is good at, what they are not good at and what they are poor at. An exam system that gave everyone an A grade would be as pointless as a regime that gave everyone a U.

So on the general principle that grade inflation is a bad thing that should be discouraged, Mr Gove is right. The problem is the practical one of doing something about it without being unfair to the cohorts of pupils who start sitting exams when the previous trend of ever-improving grades is put into reverse. That is the tricky challenge that has faced the education secretary, the regulator and the exam boards. And they've made a mess of it.

Among angry teachers and disconsolate pupils, there is a particularly loud outcry about shifts in the grade thresholds in GCSE English. What appears to have happened is that the exam boards suddenly panicked when they saw that there would be an unexpected rise in the top grade pass rate. So they steeply raised the grade boundaries at the last minute. As a result, many students who would have been rewarded with that vital C had they taken the exam in January have instead been stamped with a D. That is cruel on those students. The difference between a C and D, especially in English and maths, will be critical to their futures because it is the difference between securing a place in college or sixth-form to study A-levels and being rejected. Some of Mr Gove's beloved academies are up in arms, pointing out that this abrupt change has had a particularly severe impact on children for whom English is a second language and disadvantaged teenagers in general. One of the education secretary's favourite heads calls it "butchery". The boards are expecting a record number of appeals. There are rumbles about legal action.

What has happened this August illustrates a wider unfairness that will penalise thousands more pupils in the future as the Gove doctrine begins to bite. This potential injustice will have struck anyone who has children on either side of the divide. I have three daughters. The oldest two are through both their GCSEs and their A-levels. One is at university and the other has secured the university place of her choice. What the education secretary does to grade boundaries cannot affect them. My youngest daughter still has most of her exams ahead of her. She could do just as well as her older sisters and yet be rewarded with worse grades. This would say nothing about her intelligence or diligence, but only that she ended up on the wrong side of a change in political fashion.

Thinking about how to square the principle of stopping grade inflation with being fair to pupils in practice, I can only come up with one just solution. That is to scrap GCSEs and A-levels altogether and start again with new exams under new names. It would then be obvious that those who had spent their schooldays under the stern regime of Mr Gove had faced a different test to those who sat their exams in the pre-Gove era. Universities and employers would know that they were being asked to compare apples and pears.

This matters even more because not only does the education secretary want exams to be harder, he also seeks to increase the number of them. As important, if not more so, as his ambition to make exams tougher is his hostility towards other measures of ability, such as course work and controlled assessments. Mr Gove wants much of that to be replaced by exams in the future. Yet a sophisticated debate about how we test the performance of children would also incorporate the thought that exams are not the last word to be said about attainment.

I enjoyed taking exams. I did so for the same reason that I suspect Mr Gove loves exams. I enjoyed them because I was good at them. They are a useful and important method of providing benchmarks of performance, giving shape to teaching and setting goals for studies. But the capacity to engorge a lot of knowledge and then disgorge it on to paper under time pressure is only one form of intelligence and, when you think about it, a rather specialist ability not always all that relevant to real life and the world of work. It is not self-evidently superior to measuring whether a pupil is capable of sustaining their studies over a long period through coursework.

Anyway, we must now give our overall assessment of how Mr Gove, the regulator and the boards have done this summer. The source of all the trouble, angst and outcry is that the education secretary set himself the wrong exam question. The wrong question was: "How can we end grade inflation?" The right question was: "How can we end grade inflation without being manifestly unfair to thousands of children?" Mr Gove wants harsh marking and he is going to get it from me because he never properly addressed the crucial question. I give him an F. For the sake of those children, let us hope he does better in the retake next year.