Many people in these allegedly enlightened times are afraid of thinking. They cleave to their opinions as to an old coat that has become worn, shapeless and finished.
In many cases, those opinions are garments, acquired for fashion's sake and retained for the same reason. Their owners become angry and resentful if you try to persuade them that they are mistaken. Yet, in a few select places, it is still possible to change minds by argument.
University debating societies can sometimes discover the truth, a thrilling and exhilarating process.
Over the past few years, I have taken part in debates on many campuses across the country. As a registered reactionary, I sometimes grow tired of being asked to argue about homosexuality or immigration, but it is a sort of duty.
The grander affairs are not always the best - Exeter and Durham universities stick in the mind as among the most enjoyable and satisfying.
In my experience, Cambridge Union scores heavily over Oxford Union for quality of debate and for that shiver of excitement that concentrates the mind, sharpens the tongue and makes the blood flow faster.
That is partly because of Oxford's habit of inviting too many speakers and lingering too long over the pre-debate dinner, so that by the time the contest reaches what ought to be its height, many are sagging in their seats, battling yawns or slipping away.
Oxford audiences - and I don't just mean the Union here - are also the most intolerantly liberal of any. This city, which happens to be my home, is impregnated with a dank leftist smugness impervious to reason.
I was recently at an Oxford forum on capital punishment. I knew that I would lose. There would be more chance of persuading the British middle class that the earth was flat than that premeditated murderers might sometimes be better hanged than kept alive.
Believing that a debate without a vote is like tennis without a net, I asked for a show of hands at the end and so had only myself to blame. Even I was shocked by the pitiful number of people who supported my case - despite the fact that there were two anti-hangers against me, and despite... oh, well, modesty forbids further comment.
There are some subjects on which independent thought is dangerous these days.
But it is not always so. On cannabis, where the Government and much of the media have already surrendered to the legalisers, a good hard argument can get a good strong vote.
Drug advocate Howard Marks is one of the most popular speakers on campus, but I - who am not popular - have beaten him once and ran him close on another occasion.
Howard is a true friend of freedom of speech. We first met at a National Union of Students conference fringe meeting where I was ordered from the platform by politically correct zealots. Howard insisted on walking arm in arm off the stage with me.
Then and since, I have realised the value of those debating society conventions of formality, impartial chairmanship and of making a proper effort to listen to opponents. Without them, liberty of speech is lost. But how long will they survive?
In our brutally modernised society, those who play Westminster games at the Cambridge and Oxford unions are much less likely to reach either front bench than they once were. Ministers seldom if ever bother to visit them, scorning debate at the elite universities as they scorn it in Parliament.
The two Oxbridge unions themselves are more than a little moth-eaten, casting about for new ways to attract members who are not that interested in politics.
Let us hope that all such societies - and the majestic ideals of fairness and free thought - can survive these grim times.
Peter Hitchens
Columnist
Mail on Sunday