Imagine a school where the headteacher is a Muslim who wants a Caliphate; the deputy head is a creationist; there is a member of the British National Party teaching history; sociology is taught by a Stop the War activist who “understands” the motivations of the 77 bombers; the special needs teacher is a Jehovah’s Witness; the English teacher is the New Labour leader of the local council, obsessed with combating anti- social behaviour. Other teachers are UKIP members, Tory monarchists, deep environmentalists. And the school pupil support team consists of ageing hippies who proffer alternative therapies to pupils, staff and parents.

Would you send your children there? I suspect that most parents would run into the next catchment area rather than enrol their children in what looks like a school for extremism.

The question that is usually asked by concerned union or professional representatives when faced with the more right-wing or fundamentalist views amongst those mentioned above is: “Should we let these people teach our children?” Or, as Christina McAnea of Unison said of the BNP in last week’s TES front page story, should we allow them to use schools as a “breeding ground for . poisonous views”? The answer must be an unequivocal Yes.

Now, I have no sympathy with any of the views this motley crew may express inside or outside the classroom. But the most poisonous thing of all would be to ban their poisonous views. That is the most anti-educational thing possible. It gives out the authoritarian message that we have reached the truth on these matters and nothing more must be said.

The real problem is not extreme views but the absence of debate in schools or wider society. Stories of extremist views being expressed and their consequences for those expressing them are few. Yet the publicity they get sends out a symbolic message: don’t argue, think or criticise - or else .

There’s a lot less space today for teachers to do what they should do, which is to inspire interest in school subjects. They’re expected to teach the government line. Taught to teach to the script, teachers tend not to like debate. Anyone who has different ideas runs the risk of being called “offensive” or “unacceptable”. Part of the blame for this lies with school leaders, who feel that allowing the expression of critical or unorthodox views might affect their promotion prospects or the cash flow into schools. But rather than being too cowed or cowardly to debate, teachers should ensure that free speech is allowed. There are two possible defences they can use.

There is an easy, or weak defence for allowing people to teach, whatever their “offensive” social views. If teachers do what they should and teach their subjects well, without bringing in their peculiar views, then it is quite acceptable for these views to be held in private. What many may call bad people can be good teachers, according to this weak defence.

However, I would want to make what I call a strong defence for allowing people with “offensive” ideas to teach and to say what they like. Mainstream views are not prohibited in the classroom and children are told they are too fat, too thin, too violent, too alienated, too wasteful, or whatever political panic is pursued in the curriculum each term.

If this is acceptable, why should extremists be silenced when mainstream views are not? What is more extreme than New Labour’s diminished views of children as hopeless cases that need to “learn to learn”, or have their self- esteem improved, or to take happiness classes, or to be counselled and guided in all aspects of their lives? Teachers who hold equally eccentric or offensive views should bring them into the open so that children can hear them and challenge them and make up their own minds about what they hear.

There is a caveat, as even John Stuart Mill excluded children from exposure to full freedom of speech. The reason is that they are not mature and need to have ideas put before them in a mediated way that is appropriate to their level of intellectual development. But this restriction is just a technical one and any good teacher can put ideas across in ways proper for their pupils’ developmental stage.

Teachers know that even young children can question and argue. They are not easily convinced, particularly when the authority that teachers had because of their knowledge of their subjects has weakened.

But whatever they are taught, as millions brought up in religious schools regularly prove, they grow up and many change their views. Sacking teachers, or banning their offensive views will make children less able to challenge them and less able to grow up.

The trouble with the weak defence is that it is not possible any more just to teach your subject, and only extremists defend a depoliticised liberal education based around subjects. Any such defence will be vilified as reactionary, right wing, elitist and opposed to the real task of meeting children’s needs through “personalisation.” This is an inversion of the truth, but the arguments are not heard.

What teachers need is a charter, similar to that in universities and colleges, that allows them to “question and test received wisdom and put forward . controversial and unpopular opinions” without losing their jobs or any privileges they have in their schools. The unions and professional bodies should put that at the top of all their mission statements, charters and codes of conduct. That would be a welcome outcome from the present outcry about right-wing teachers, and the majority of teachers would welcome it as a strengthening of their professionalism.

- What’s your view? Email us at letters@tes.co.uk

Dennis Hayes, Head of the Centre for Professional Education, Canterbury Christ Church University and founder of Academics for Academic Freedom.