Britain is a society on the move -- and I don’t mean the increasing numbers of people moving into and out of the country. I mean that the ground rules for getting on together are changing, with the result that some of us feel a little confused.

Take university education. It is no longer safe to assume that if you get straight A’s in the school-leaving exam you will get into a university of your choice. New rules being adopted by universities, with official encouragement, decree that it is more important to ensure that people from deprived backgrounds get to university, so it is necessary to check on your background when you apply. If your family has a strong history of university-attendance, it doesn't seem fair that you should merely add to that; you must understand that in the interests of fairness it may be necessary to deny you a place.

Now, another thing is global warming. Because it's so important, and it will be so dreadful if the whole earth gets unbearably hot and we suffer drought and famine, we've got to take a fresh look at our whole understanding of our institutions. It may be that things we've always taken for granted – the impartiality of the courts, for instance, or our concepts of what constitutes damage to private property, need revisiting. Thus, activists in Greenpeace recently walked victoriously from a courtroom after hearing that their attempts to sabotage some industrial plant had been deemed not to merit any censure or punishment. Painting a slogan on the chimney stack of a major producer of heat and energy was OK -- even though it cost the company £35,000 to remove -- because they claimed to be doing it out of concern about global warming.

The two examples I've given above are part of what happens to institutional thinking when it gets into the grip of an ideology. It can happen with surprising ease. For several decades, universities in Eastern Europe took a collective stance in favour of a Marxist interpretation of social dynamics. It was not deemed appropriate to award a degree to anyone who seriously deviated from the Marxist understanding – some minor deviations were permitted, but the overall concept had to be there.

Institutional thinking can make people feel very cosy, even smug. It sort of feels good to know that you are working for social equality, or helping to combat global warming. It gives you permission to sneer at others who are thinking outside your box. Within the box, the institutional glow is not only enjoyable but after a while becomes so familiar that people outside do seem to be a little odd. The problem is that don't always act as if they are in the wrong. They will insist on peering in at you and laughing, or even trying to break into your box to explain to you that you might be wrong.

In the case of university admissions here, the policy seems to be still at the level of recommendation and instruction to some academics who currently insist on committing themselves only to academic standards. Apparently the official line is that they've got to be told to get their heads into the social analysis and action box. In the second instance, the significance of the Greenpeace victory was ably summed up by the leader of the saboteurs: "This verdict marks a tipping point for the climate change movement. When a jury of normal people say it is legitimate for a direct action group to shut down a coal-fired power station because of the harm it does to our planet, then where does that leave Government energy policy?”

Indeed, where does it leave government?

Where next? Not sure. If eastern Europe is any guide, we are in for a lot of very stupid and unjust institutional decisions, resulting in a good many problems for us all. By the time a groundswell of voices is calling for sanity, the institutional habits may well have extended to include the need for imprisonment without trial for various periods, or exclusion from public office, or professional life, of people who hold these unacceptable opinions.

Worrying? Of course it is. And more so than you think. Consider: a teacher at a state school who opined – perhaps at a church event, or on a radio show discussing social trends – the personal view that marriage can only be between a man and a woman and is binding for life, that “same sex marriage” is biologically and legally an absurdity. Is there a likelihood that such a person could suffer major professional disadvantage, possibly even loss of a job?

Now consider another teacher. This one is committed to the notion that wind power can produce sufficient energy for a major part of our needs. She launches her pupils into a large wind-farm project and devotes a great part of her science lessons to this. They visit wind farms, they design wind farms, they write about wind farms, they win an award for the school's support for wind-farms. They are taught to despise other forms of energy production and regard them as inferior and unworthy of serious study. Five years later, the futility of wind-farming is revealed – wind cannot produce a fraction of the energy we need, it cannot be stored, the huge structures requite high energy-expenditure in their construction and maintenance and gravely damage the environment, killing birds and other wildlife and wrecking scenes of former natural beauty. Wind-farming is seen as fundamentally flawed – like old ideas such as “bleeding” patients who suffer from infectious diseases, or the Chinese habit of crushing little girls' feet and binding them tightly.

Which teacher caused more damage to her pupils' education, limiting the scope of their knowledge and leading them down too narrow a pathway? Which, at this moment, would be cosily inside the institutional-thinking box and likely to be given every encouragement and support?

This is not a plea for anything and everything to remain an open question. There is probably room for an institutional box in our thinking: that murder is wrong, for example, that 2 plus 2 = 4...oh, and much more. The point I'm making is that it's a question of what we put in the box, and how we treat its contents.

We need to recognise that the box is not for enclosing minds but for nourishing them with its contents, so these contents should be things of lasting and proven worth: the Ten Commandments, some soul-stirring prose and poetry, a strong and systematic teaching of history, the lives of great men and women, some understanding of great inventions in engineering and of achievements in medicine and other sciences, lots of music, vast quantities of glorious art... these are the things that should be part of our collective consciousness and influence the institutions which shape our common life. Not – repeat not – the passing fads of social engineering, however worthy they may seem just at the present.

Joanna Bogle writes from London.