When one academic challenged the orthodoxy on Aids, he was spurned by his peers;when another enraged the public with racial theories, he was allowed to continue in his work. Next week, in a special issue of Index on Censorship, Colin Tudge, Gordon Stewart and Marek Kohn are among those who turn the spotlight on contentious issues in science.

Big business is exercising increasing control over science and the high technologies that flow from it. Government policies in the United States and Britain from the 1970s onwards have encouraged this. Before 1970, scientists in British universities and government labs were told not to talk to industry, but after Lord Rothschild's report in the early 1970s they were encouraged to seek industrial funding, with all the restraints that this imposes.

One university doctor of my acquaintance often comments that it is difficult to find any research on nutrition that has not been financed by industry, and that it is almost impossible to find a truly "objective" opinion.

The trend is exacerbated by the need to patent information, and so to claim royalties. In the early 1970s, the great Cesar Milstein at Cambridge created "monoclonal antibodies" - highly "purified" antibodies that attack one antigen at a time - and so transformed the whole of biotechnology. He felt his creation should be for the benefit of humankind and did not patent his discovery. Nowadays, such saintliness would be considered ludicrous.

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Patenting, as originally conceived, is intended to liberate ideas: once a notion is patented, everyone is free to use it, provided they pay. Without patenting, everyone would be obliged to keep their notions permanently to themselves. But today everything can be patented, down to human genes, and no one talks to anyone for fear that future patents will be compromised.

Then there is the matter of grants. Scientists must fund their work and they can no longer simply dip into the general pool of grant money. Professional scientists spend several days a week applying for grants, a tremendous drain on endeavour. Increasingly, too, these grants come from industry, which mostly means multinational companies that have their own axes to grind. Those who seek grants must appeal to the whims of their financiers, which they typically do by the use of buzz words. Isaac Asimov once commented wearily that if you wanted money to do research on the moon, you had better drag in the word "cancer", only to be told of one ingenious proposal that did just that.

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It is childish to suggest that multinationals are ipso facto evil, but their hold on high technology is certainly pernicious. It perverts the course of science and, more dangerously, it perverts the course of all human life and, indeed, of all non-human life.

We can illustrate this by the fashionable topic of genetic engineering. We can envisage good uses for it - for example, to create robust, effective vaccines against foot-and-mouth disease in third world cattle, which probably cannot be done without genetic engineering. Genetic engineering, however, is not typically used for such purposes, because high-tech is expensive and third world people have no money. Instead, it is used in rich countries to make tomatoes with a longer shelf-life - a trivial pursuit, intended only to maximise profit. Again, the point is not that profit is bad, only that maximising profit should not be the leading motive. Thus high-tech effectively belongs to big companies: they alone can afford it, and government has largely opted out - and so it is used for the purposes of big companies.

The reason for objecting to big industry is that it forces the world to operate in ways that suit it, and everything else goes to the wall. Food provides prime examples.

Agriculture dominated by big industry tends towards monoculture, because this brings economies of scale, and monoculture excludes wildlife. Even grassland these days is monocultural -exclusive swards of rye grass. The traditional meadows, rich in wildflowers, are museum pieces. No wildflowers means no insects: no insects means no birds. Skylarks, tree sparrows, an alarming list of species that we took for granted 20 years ago are starving to death as thoroughly as they were poisoned by pesticides in the 1950s.

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The products of monocultural agriculture are then fed into a small cadre of supermarkets. This "vertical integration" may be good business, but if we do not resist it, we will soon be eating only what it is convenient for those businesses to provide.

The dominance of multinationals is made possible by high-tech, and high-tech is the scion of science. Thus science appears evil: not a Frankenstein in this context, but a Strangelove, the all-powerful controller. Yet science ought to be beautiful, a liberator. We can still resist this misappropriation, but only with knowledge. Information is the key to freedom. Those who suppress information, including the scientists who fear to share their ideas, must be seen as the enemies of society.

Colin Tudge is a research fellow of the Centre for Philosophy at the London School of Economics.