London Briefing: Most intelligent people become more right-wing, or conservative, as they get older. There are lots of reasons for this, but the main one is the growing realisation that our ability to effect change is very limited and, when we try, there are always unintended - and often perverse - consequences.

The paradox of intelligence is that the more we possess, the more aware we are of our limitations.

In terms of social and economic policy, we have learned after two centuries of experimentation that the instincts of the early classical economists were absolutely right. Less is more.

That ultimate experiment in economic policy, socialism, gave rise to all sorts of unintended consequences, not least being the very low level of very equal incomes that most people were able to achieve.

That other great socialist achievement, state tyranny, was another unfortunate side-effect unforeseen by Marx and his associates.

One aspect of the current debate over global warming that is not remarked upon is the way the debate has a left/right dimension. If you want to know anyone's political colour, ask them about their opinions on climate change: if they tell you that it is all man made and we must do something about it, you know that you are dealing with someone who, at the very least, is a definite shade of pink. Anyone who suggests that climate change might be real but that we should be a bit more humble about our role in it is, of course, a modern-day fascist.

Intelligent right-wingers instinctively doubt our ability to affect anything very much and are very sure that if we try to reverse what may, or may not, be man made, things will definitely end in tears.

Tony Blair's journey from left to right has been in the news, again, recently, with details emerging of his very first requests to be allowed to stand for Parliament.

Early signs of thoughtfulness in the form of an attenuation of the rabid socialism trendy at the time are nevertheless present in his pleadings to then Labour leader Michael Foot.

Since those halcyon days, Mr Blair's almost total transition from socialist to conservative is evidence of an underlying intelligence that has been kept well-hidden in most other areas.

Blairism, of course, is the ultimate case history of unintended consequences. Iraq is the most painful example, of course, but there are plenty of others, if a little less consequential.

Businessmen have to deal with the unforeseen every day. The difference between success and failure is often a result of how change - or sometimes crisis - is managed.

Stuff happens. A small example: Blairism has highlighted the need to deal with yob culture: the government has come up with a range of measures, notably "anti-social banning orders" (Asbos). Businessmen, never slow to spot an opportunity, have tried to come up with their own Asbos.

And not, exactly, in the way that we might have expected.

One such company hails from Merthyr Tydfil in South Wales. Compound Security invented a device that exploits the gradual deterioration in hearing that comes with maturity (left and right wingers are equally affected).

They invented a box of tricks that emits a high-pitched shriek that only kids can hear. And it is so painful, apparently, that a gang of louts will instantly disperse.

But the product that has emerged from this that is selling like hot cakes is a high-pitched ringtone for mobile phones: the kids have reverse engineered the idea and now carry mobile phones that emit the shriek as a ringtone. Young people can hear the ringing, but their teachers, the ones over 30 at least, can't.

Asbos, like most grand policy ideas, don't work and have utterly unexpected consequences.

Mr Blair's woes are in direct proportion to the size and number of policy interventions he has made. The trouble with nine years in government is that he has had plenty of time to make lots of policy.

That's why he is unpopular; that's why we eventually vote out any government. It's why Enoch Powell was absolutely right when he said that all political careers end in failure.

David Cameron is running around promising us lots of nice policies. His political future would be much more secure if he only understood what being a Conservative actually means: not much, in terms of policy, at all.

Chris Johns is an investment strategist with Collins Stewart. All opinions are personal.