The rise and further rise of the so-called ‘Precautionary Principle’ (PP) – particularly when it comes to trying to assess the environmental impact of past and future human activity – is, some say, a defining moment in intellectual history: "the most radical idea for rethinking humanity’s relationship to the natural world since the 18th-century European Enlightenment".

What is this Principle? Its supporters say that it is nothing but common sense: "All it actually amounts to is this: if one is embarking on something new, one should think very carefully about whether it is safe or not, and should not go ahead until reasonably convinced it is. It is just common sense."

But things are not so simple.  "If your position is that you don’t accept any incremental risk, you are in effect saying no to all new technologies, whether it be a better anaesthetic, a better car, a better aeroplane, a safer environment for children – in fact anything worth having."

The PP itself is ‘something new’. So as a common sense precaution should we think very carefully whether it is safe or not? Maybe it too will kill people.

In any case there are other ways of looking at how our fears, real dangers and the law interact. Should they too not be given a coherent airing by senior policy-makers before adopting formally one Principle over others?

A big subject.

My professional concern about PP is that far from promoting policy common sense it can diminish it.

Take the refurbishment of the British Ambassador’s residence in Belgrade back in 2001. The building had been neglected during the long Milosevic years. Everything which could be painted was either Excrement Brown or Rose Pink.  The main reception room looked like the forlorn warehouse where all the worst sofas and curtains in the FCO crawled away to die in shame.

So it was agreed that we should upgrade things in the next couple of years. But we had not reckoned with "what if" PP as articulated by the FCO works people…

One idea we had was to remove the vile dark sticky polish and ugly carpets from the original nice woodblock floors and go for a lightly coloured, varnished modern look. But when we asked for this to be done along the upstairs landing we met: "what if a child skids and shoots up and over the landing and plummets down and dies?!"

We asked for the kitchen to have something other than industrial strip lighting, to make it a more pleasant place to work. "What if one of the cooks is ill and cuts himself and drips infected blood into food being prepared for a member of the Royal Family?!"

Work began to replace the nasty tin sentry box for our local staff Serb security team with a small brick building. I happened to stop by and asked why the roof was such a fatuous design. "It is being made of reinforced concrete. What if terrorists attack and try to break in through the ceiling?"

In each case I had to order them all to stop being ridiculous and come to a calm, elegant solution. Had I not done so the taxpayer probably would have had a worse and more expensive outcome.

Yet countless stupidities are not stopped. How does one cost this mess?

Observe the alarming fertility rate of (and environmental destruction caused by) the road-signs proliferating on the A420 between Oxford and Swindon. "We already have two large road-signs warning drivers of that roundabout 300 yards ahead. But maybe we should add four more, two on each side of the road –  just to be on the safe side!"

Fine. But where does that argument stop? There are already sections of that road where there are so many signs coming thick and fast it is dangerous to try to look at them all. More and more road signs seem to mean less and less litter collecting. Squalor tempered with stupidity. Or vice versa.

A final example. When our daughter was born in 1999 we bought a new sturdy high-chair from John Lewis. Imagine our annoyance when we put it together and it had no wheels for moving it to and fro in the kitchen, even though the picture on the box showed wheels. We called the shop to remonstrate, only to be told that "EU rules" said that for safety reasons there could be no wheels on high chairs, lest infants somehow propel themselves across the kitchen, crash into a hot-plate and self-incinerate.

I pursued this with the FCO EU team. They discovered that it was not in fact an EU edict as such which had caused this decision, but some other European-level Health/Safety convention. As if that somehow made it any better.

All this bureaucratic rubbish stemming from twisted versions of PP is part of a deep process of self-inflicted Stupidisation. What is scary is that it is like a malignant virus infecting the deepest parts of the operational public policy process in all sorts of unpredictable and unexpected and ultimately irrational ways.

Why? Because let’s be honest. Of course we need to think about what we do. But in the process of weighing options and trying to choose a reasonable way forward, over-focus on PP tends to empower those with high-energy neurotic anxieties and/or bizarrely lurid busybody imaginations, and compels taxpayers to waste astonishing sums of money accordingly.

How to stop it?