iberal, without its capital letter, is one of the words that I choose to define myself as a person - how I think and who I am. I considered myself to be a liberal parent, and still do. I struggled to be a liberal teacher, and I’m certainly liberal in my approach to education and to life.

Why does that statement sound like some kind of confession, some kind of coming out, even in 21st-century Britain, where a large percentage of people actually vote for a party with the word “liberal” in its title, and David Cameron has just declared himself to be a liberal Conservative?

Perhaps it’s because I’ve just come back from the United States, where the religious right have successfully made liberal a word you dare not use, a word associated with all that is wrong with American society, including the education system. It’s also a word that those on the right in Britain and, indeed, many in New Labour have also tried to rubbish.

On the plane to the US, I read a newly-published book by the British philosopher Stephen Law, called The War for Children’s Minds. It’s a book that should be read by teachers, parents and politicians. It helped deepen my understanding about why teaching is a political activity and why the key issues of discipline, behaviour management and motivation that teachers wrestle with in classrooms day-by-day, minute-by-minute, are not simply about honing techniques but about who you are, your beliefs, your philosophy of life. As Law says, it’s about how liberal or authoritarian you are.

There’s another emotive word. Few teachers would want to describe themselves as “authoritarian”. It’s not politically correct these days, or is it? Much of the talk in staffrooms and elsewhere is that there is not enough respect for authority in the modern world. If challenged, people will say that of course we want to trust young people and to help them to be able to think for themselves, but not too early and not too much. After all, if they are too young or too badly behaved, they are not trustworthy.

We think we know what being liberal and authoritarian are, but Law makes a crucial distinction between freedom of action and freedom of thought, when considering what divides liberals and authoritarians. The liberal approach to education is about freedom of thought, not freedom of action.

He points out that liberalism has become equated with a relativist “anything goes” approach where there are no rules for behaviour and people should do what they like. Nothing can be further from the truth.

Everyone except the most extreme liberals believes that, when it comes to freedom of action, there should be at least some rules. You can be liberal and believe that teachers and parents are the legitimate holders of a certain power. They are permitted, indeed expected, to discipline children when they misbehave. But how teachers should use that power, how restrictive these rules are and how aggressively they are enforced is one of the issues that divides liberals and authoritarians.

Where Law believes everyone should be essentially liberal is in our attitude to freedom of thought. Here there is a line down the middle and everyone who believes in a healthy democracy should be firmly on one side of it. That line should be defended against all authorities, religious or political, who want to tell you what to think and believe and what moral judgments you should make.

Law’s book focuses mainly on moral education. He goes against the fashion by arguing that we should be very liberal indeed in our approach to moral education. For him, it’s about exploring issues together, arguing a point of view, looking at the evidence.

I believe this idea applies across the curriculum. Sound reasoning and critical thought act as filters to false beliefs in history and science, for instance. Many authoritarians want you to by-pass that filter and believe what they say about the world, to deny the Holocaust or to believe in new creationism, for example.

Over the past 100 years, democracy has proved to be by far the most humane and effective form of government, but it is under threat today from Christian and Islamic fundamentalism. Critical thinking and free expression are the heart of a healthy democracy and are a much better defence against the suicide bomber than curtailing our freedoms and banning hair gel from planes.

All teaching is a political activity. No teacher can be neutral. We can choose to stand beside young people, helping them to think and learn and to find their own place in the world, in recognition of the fact that all real education must be about self-education. Or we can choose to stand above our pupils, telling them what they should know and should do and seeing them as passive recipients whom we need to mould into good citizens.

Where do you choose to stand - beside or above your pupils?

Ian Smith is the founder of Learning Unlimited