A cautionary tale about the precautionary principle

Some principles form the basis of science. Others purport to regulate the way science and technology develops. But are such principles scientific themselves?

The so-called precautionary principle - PP here for short - is a prime example. It has been used by public and government regulators to restrict the use of new technologies and their products. But is it scientific or, as some critics have claimed, anti-science?

Enshrined as part of the European Union's governance legislation, its most powerful effect has probably been the almost total ban on commercial genetically modified food within the union, and the under-funding of research into GM products.

There have been fierce public debates about the validity of PP in Britain and the European Union whereas it figures far less in the US and is almost non-existent in China. The Guardian newspaper in Britain last month ran an extensive and provocative debate on the principle.

While it seems sensible to be cautious about new technologies, the excessive application of PP can also lead to, and indeed has caused, fears, confusion and damage to the public interest. An example is the decade-long row over the safety of the combined measles, mumps and rubella vaccine, following a sensational study in the late 1990s, since discredited. People were taking precautions against a perfectly safe and key vaccine for children. As a result, there have been sporadic outbreaks, most recently of measles in South Wales.

One problem with any debate about PP is that different people have different definitions for it. I discern at least two - the weak and strong - versions. Others may identify more. The weak version is just common sense and should be adopted by everyone, not just government agencies, though it probably doesn't deserve to be called a principle, let alone a scientific one. It is: "Hey, there are danger signs so we better be careful about this technology and find out more before introducing it widely." This is just a responsible precaution. People have done this all the time, long before someone coined the phrase PP.

Then there is the strong "you never know" version of PP. This is most liable to abuse and is often exploited by ideologues against whatever science or technology they happen to be campaigning against, for example, Greenpeace's decades-long campaign against GM products.