Leading article: The dangers of trying to pick winners

The latest area of Government spending that has come under the public microscope ahead of the Comprehensive Spending Review is the £6bn annual science budget. The Business Secretary, Vince Cable, delivered a speech this week saying that, to cut costs, his department will stop funding "mediocre" research. And the Science Minister, David Willetts, yesterday stressed the need for universities to come up with ways of earning private money from their research through commercial development in order to reduce their reliance on the state.

We can all surely agree that the state should only be funding high-quality scientific research, especially when economies are desperately needed in the public finances. It is hard to argue (though some university lobbyists have attempted it) that all research that takes place in British universities is of an equally high standard. We can also agree that universities should work harder at producing commercial spin-offs. Other rich nations such as the United States and Germany have a better record of squeezing entrepreneurial fruits out of their university sectors.

But all this is much easier said than done. Mr Cable says he does not want to hand down a uniform budget squeeze for all areas of research, an approach he characterises as "salami-slicing". But that means he will be putting his department in the position of attempting to "pick winners" from the panoply of areas of scientific research in Britain.

That will be an invidious task. It is often very difficult, if not impossible, to tell in advance what areas of research are going to produce breakthroughs. As Colin Blakemore, the former head of the British Medical Research Council, has put it: "Some of it doesn't produce the results that were expected. That is the nature of research. Sometimes it doesn't work."

And the simultaneous ministerial pressure for universities to encourage commercial spin-offs from pure research has the potential to muddle thinking. There might be a stunning success in an area of research which, though it pushes forward the frontiers of human knowledge, has no practical application. Alternatively, there could be some unlikely area of research which yields a lucrative product. The danger is that an over-emphasis on financial payback will distort funding decisions.

Mr Cable says he will be guided by the judgement of academic councils on which research is truly world class. And he points to a 2007 report by the former science minister Lord Sainsbury which showed a high correlation between successful commercial applications and high-quality fundamental research.

That approach is fine as far as it goes. But this cutting exercise is bound to be full of marginal cases. The academic councils that grade research are not infallible. And deciding what new research to approve will be a question of judgement rather than evidence. This will inevitably be bloody and divisive work.

It is vital for Britain that the Government gets this right. Scientific research is an area in which we have an impressive comparative advantage, as the latest QS World University Rankings this week make clear. Cambridge University was voted top for research into the natural sciences by academics from around the world.

Pure science research is one of our national strengths. There is a great deal of scope for intellectual and commercial advancement in areas ranging from stem cells, to low-carbon energy, to satellite technology (and countless other things that ministers have not even yet thought of). The challenge for Mr Cable and Mr Willetts will be to trim the branches of British science, without doing any fundamental damage to the tree.