If you know your onions, you'll steer clear of setting targets

The Labour government has announced more than 8,000 new numerical targets since coming to power in 1997. David Boyle's The Tyranny of Numbers is an amusing antidote to the tick-box mentality that has become the hallmark of Blairism: if it can move, set it a target.

Academics are very familiar with the endless form-filling and seemingly mindless bureaucracy that accompanies this approach. This book will appeal across all disciplines. In many ways, it is an ideal book at bedtime, for it is serious yet at the same time written with a skilled, light touch.

The dust jacket may give the wrong impression of Boyle's arguments. It proclaims that "he reminds us of the dangers of taking numbers so seriously at the expense of what is non-measurable, non-calculable: intuition, creativity, imagination, happiness". This could easily be the theme of a New Age rejection of materialism. But Boyle is far more subtle than this, and he recognises the benefits that prosperity can bring.

A key point that runs through the book is "if you choose the wrong measure, you sometimes get the opposite of what you wanted". Boyle illustrates this with many examples. A topical one is the government's promise to cut hospital waiting lists by 100,000. The response from administrators was to set up secret waiting lists for people to get to see a consultant, before they became officially on the waiting list. And simple operations were given priority at the expense of difficult ones, regardless of medical need.

Boyle is describing here an important phenomenon in the social sciences: the ability of agents - individuals and firms - to adapt their behaviour in the light of circumstances. Standard economics captures this through the response of agents to the price mechanism.

In the early 1920s under war communism in the Soviet Union, a list of vegetables was drawn up whose production was to be controlled and regulated by the state. Onions were unaccountably omitted, and the result was a glut of onions in Moscow's markets. But the reaction can go even further, to individuals altering their behaviour in the light of what others do. So it is only the brave or foolhardy individual who can continue to hold a contrary view when financial markets are crashing.

Boyle's real villains are the founders of utilitarianism, Jeremy Bentham and James and John Stuart Mill. Mill's bizarre education is described with amusement - learning ancient Greek for six hours a day at the age of three, with no holidays. "There was no birching," Boyle notes, "but his father's sarcasm was almost as unpleasant" - truly the inspiration for the Monty Python Dinsdale character and the weapons he used to subdue his gang of East End thugs.

Boyle believes - though the point is not pushed too hard - that the uncertainty about outcomes arises from the chaotic nature of social and economic systems. This is a common error. It is complexity, not chaos, that characterises these systems. They are systems at the edge of chaos, dynamic and very hard to control in a rigid, precise way. This apart, the book is a pleasure and it deserves a wide audience.

Paul Ormerod is a director of Volterra Consulting.