The message of Post-Normal Science is that policy-relevant science is affected by uncertainties and value-commitments. As we say, 'facts are uncertain, values are in dispute, stakes are high and decisions are urgent'. This is explained in terms of 'complexity theory'. That is not the same as 'complicated', which refers to lots of messy variables. A complex system is one where there is no single privileged perspective. For resolving complex policy issues, scientific demonstration must be complemented by a broad societal dialogue.

Appreciating complexity is necessary if we are go go beyond the 'simplistic belief systems' that have governed so much of our thinking, including science, in the past. These are typical of what the philosopher T.S. Kuhn called 'normal science'. This consisted of puzzle-solving within an unquestioned and unquestionable 'paradigm', a framework of facts and values. When the puzzles couldn't any longer be solved, and when the scientists couldn't 'suppress or evade' the anomalies, the situation was ripe for a 'scientific revolution'. After that, a new dogmatism would take hold. Kuhn didn't necessarily like this picture, but he believed that such a regime is necessary for the progress of science.

The clearest example of this unflattering image of science is found in textbooks. It's hard to deny that textbooks convey an impression of infallibility and dogmatism. There is no space for doubts and criticisms. For every problem, there is one and only one correct answer. Problems with many answers or none are inconceivable. Small wonder that those who have survived ten years of such an intellectual diet tend to have a simplistic view of reality! Kuhn actually compared science teaching with orthodox theology; and it is an uncomfortable parallel.

In all such 'simplistic belief systems', scientific or otherwise, there is a style of thinking that inhibits management of uncertainty and change. We can compare 'normal' and 'post-normal' styles by pairs of attributes:

Of course, the practice of high-quality science at the research front is largely post-normal in this sense. But somehow the teachers and popularisers have been constrained to present an implausible picture of indubitable facts and unalloyed progress. Problematic scientific issues are relabelled as 'environment' or 'health', so that 'science' retains its pristine purity. The great lesson of the atomic bomb, that science too can taste evil, seems to have been forgotten.

But there are signs that the public is waking up. If energy policy is not a scientific issue, what is? And we know that we will never again have gasoline that is cheaper than spring water. Every other energy source has large problems of 'waste', some of which (as the nuclear) defy solution. We now realise that we cannot predict, and perhaps cannot even control, the societal consequences of the new integrative technologies now being created. Bill Joy, of Sun Microsystems, called them GRAIN: genomics, robotics, artificial intelligence, and nanotechnology. And what happens when they converge? Can we be sure of the wisdom and integrity of those who will be directing this new mega-science?

The times are now definitely post-normal. Will science be able to change with them? Can it move from simplistic beliefs to complex understandings? The task of post-normal science is to assist in this evolution, at the next stage of history.

Jerry Ravetz

Jerry Ravetz is a Visiting Fellow at the James Martin Institute for Science & Civilisation at the Saïd Business School, Oxford