Whatever the differentiation theorists tried to make us believe, there were just two traditional models for all students, the sharp-witted Theaetetus, and the nameless and confused slave boy in Plato's Meno.
The difference is between those who catch on and require little work on the part of the teacher, and those with some level of learning difficulty.
One type of student needs challenging and the other guiding step-by-step.
It is a national disgrace that the latter student was the model for the "learner" envisaged in policy papers for the past two decades.
Policy-makers have treated generations of students as if they were dull.
But, being what they are, students have re-invented themselves as a new sub-species that thinks quite differently in response to this insulting approach.
Two students I've taught recently have made me understand what has changed.
Unlike Plato's students, they were both girls, Ruth and Zo . Ruth, a linguist, learning philosophy, was the most challenging. Whatever different ideas were presented she retreated into her own views or feelings with a stubborn determination not to be influenced and made articulate criticisms of my "elitism" and "snobbishness" for thinking that I knew more than her and the other students.
I was also told off for thinking I was right and should equally value their views as they felt very strongly about them. Her argument was that feelings could not and must not be challenged.
Zo , who was at the end of a vocational course and preparing for job interviews, was more open in expressing her feelings. She was often tetchy in response to any criticism, which she took personally.
Support (or flattery) was the order of the day, rather than challenging her or the class about their attitudes. Her feeling was that issues such as presentation were nobody's business other than the students' themselves.
Both held that their "feelings", which seemed to stretch in meaning to include thoughts and aesthetic judgements, could not be challenged.
Challenging false ideas and mistaken judgements was an offence against them. "How dare you criticise me!" seemed to be the motivation for their responses.
Thinking about the emphasis Ruth and Zo put on their feelings appeared to me to be not a religious but an "emotional" fundamentalism. My contention that errors of argument and judgement could and should be criticised was met with the equivalent of the sullen and infantile cry: "Leave me alone!"
These seemingly unproductive altercations turned out to be quite the opposite. The next week, I heard Ruth use an argument she had rejected. She said she had thought about it and changed her mind. Over a very few weeks, she changed her mind frequently, often working through new ideas independently and revelling in her changing attitudes and even challenging others.
I could hardly keep up. It struck me that this is how it should be as young people learn what they really think about an issue. Zo also changed after expressing her feelings in several conversations and emails and now we meet regularly to discuss her future, because she values lecturers who are "honest" and "tell the truth".
Ruth and Zo are typical of many students who seem to have responded to being treated as if they were inadequate by adopting a dual strategy of closing down intellectual debate while emphasising the special value of their feelings.
They reflect the Government's approach exactly, which is to emphasise the inadequate nature of student intellect and inability to acquire knowledge, while playing up their need for self-esteem and all things emotional.
The twist is that Ruth and Zo adopted a strategy that shut out both sorts of interference in their intellectual and emotional lives. The moral of this tale is that we now have an emotional rather than intellectual division between two types of student. We have two kinds of emotional fundamentalists who feel that their knowledge is built on secure emotional foundations.
This emotional epistemology is a house of cards and whether, like Ruth, they defend it, or, like Zo , they indulge it, the outcome is to undermine truth in favour of authenticity, and education in favour of dangerous emotionalism.
We need to recognise the irreconcilability between education, which means learning about the world and the way it is, and the current fashion for emotional toying with young people's hearts and minds.
There is no point in arguing for balance between the cognitive and emotional. It's too late. We've moved from intellectual forms of education to an emotional focus that is anti-educational. Today's students may be difficult but, if challenged about the world and not merely emotionally indulged, they will respond.
Dennis Hayes is head of the Centre for Professional Learning at Canterbury Christ Church university