Anthony Seldon, the master of Wellington College, has a series of proposals to reform education. The most radical is that state schools should charge fees to wealthy parents.

Now, headmasters do get funny ideas. It's part of the joy of them: the single, weird opinion that reveals a flash of humanity. It's the chink in the armour of their otherwise cool, logical embodiment of authority: a fervent and unshakeable belief that cabbage is character-building or the school cat can speak.

So, what harm in Anthony Seldon thinking state schools should charge? Isn't it just a charming quirk, like your old headmistress believing everyone should learn the trumpet?

Dr Seldon, though, is an "important" headteacher people have heard of. Possibly the only one, since the other famous head was Sir Eric Anderson, provost of Eton, who retired in 2004.

As such, Dr Seldon doesn't just sit in a brown armchair, shouting his strange ideas at a long-suffering maths teacher. His suggestions were published by the Social Market Foundation and widely covered in last week's newspapers. He has discussed the plan with representatives from the main political parties. He is being listened to.

The other difference between him and your old teacher who thought it was easier to learn French while wearing a hat is that his notion is not just crazy, it's evil. I admire him for putting a new idea into the world for discussion, but the idea itself is revolting.

"Evil" is not a word I use automatically when I disagree with someone; it's Dr Seldon himself who wants his plan discussed in moral terms. The rousing final words of his proposal are: "It would be far more morally repellent to continue with the status quo than to start charging fees at top schools for those who can pay."

In brief, he says: state schools should means-test, with parents liable for a sliding scale of prices if their income exceeds £80,000 a year.

"Fees at [the most popular state] schools," he recommends, "should be the same for the affluent as the fees charged at independent day schools."

Well, he would, wouldn't he? After all, if state school fees were exactly the same as private school fees, what would actually happen? Thousands more people would shift over to the independent sector. Once the affluent are shelling out this £20k anyway, they might as well pick the school with the famous name, the vast playing field and the list of glittering alumni going back centuries.

This is not to suggest that Dr Seldon's proposal is a deliberate, devious wheeze to remove one of the major reasons for potential customers to avoid his own establishment.

Not at all; the inevitable flood of wealthier parents out of the state and into the independent sector may simply not have occurred to him. But, from his confident tone in lines such as: "There is no longer any intellectually respectable argument for claiming that state schools shouldn't charge fees", I suspect he wouldn't necessarily prefer the explanation that his idea is stupid and ill-thought-through. There's something else that may not have occurred to him. Dr Seldon's proposed reform is fuelled by the idea that rich people ought to subsidise state education. A quarter of these suggested new fees, he explains, would be kept by the schools concerned, "while the remaining 75% would be put into a pot to be redistributed amongst state schools at large".

Dr Seldon seems not to realise that a pot of money, built up by wealthy people for redistribution among state schools, is what the rest of us already call "the tax system".

Can it be that the fat-cat fee-payers at his own institution are so heavily dominated by non-doms, foreign oligarchs and domestic tax-dodgers that he's actually forgotten we have a principle of subsidy at all?

If there isn't enough money to run good state schools then you collect more tax – at national level, not at point of sale, dismantling the whole beautiful principle of universal free education and creating a division within individual schools between who pays and who doesn't!

For that is another reason rich parents might send their kids to state school: not to save money but to reduce social divisions, to give their children (in lieu of matrons and weird Latin slang) a place in a broader and more cohesive community. Rightly or wrongly, they might believe that their offspring would fare better in the long term if they grew up in a society that treats all young people the same.

But if you are such a parent – if you could afford to educate your children privately but think the world might be a friendlier place if you did not – then Dr Seldon has a message for you.

"We have to end this unfair farce," he told a newspaper, "whereby middle-class parents dominate the best schools, when they could afford to pay, and even boast of their moral superiority in using the state system when all they are doing is squeezing out the poor from the best schools."

Breathtaking! He reframes the decent social theory of many well-meaning parents as something bad. It's not democratic to school your kids with the majority; it's pushy and greedy. Black is white. That of which you're proud is that of which you should be ashamed. As he says in the report, fee-paying actually "enhances social justice".

There is a fiendish cleverness to this argument, because it's not currently possible to pay fees in the state sector. So, as things stand, by Dr Seldon's logic, what is the wealthier parent morally obliged to do? Why, move to the independent sector! To "enhance social justice".

For information about how you could pay £32,940 a year to send your child to Wellington College, visit its website.