Robert Proctor, of Stanford University, coined the term "agnotology" in 1992, when he realised we are much more interested in producing knowledge than in the way society propagates ignorance. Such concerns were the focus of a two-day symposium in May at the Centre for Interdisciplinary Research (ZiF) at Bielefeld University, in Germany. In recent years, agnotology has been extended to cover a discipline at the junction of philosophy, sociology and the history of science, its purpose being the study of ignorance itself and the means employed to generate, sustain and broadcast it.

This might seem an abstract pursuit, but in fact it addresses many of the issues sparked by the friction between science and society. The opposition prompted by new technology or harmful products often triggers the same mechanisms. A familiar example is the publicity given by the US tobacco industry to misleading studies on the alleged benefits of smoking.

Other ploys are perhaps more cou nter-intuitive. "It is less well known, but tobacco companies also spent large amounts subsidising good quality biomedical research in fields such as virology, genetics and immunology. They funded the work of several Nobel prize winners," Proctor says. "But they only encouraged this research to serve as a distraction. The idea was to build up a corpus of work on possible causes of diseases which could be attributed to cigarette-smoking. In court cases involving the industry, its lawyers always highlighted viral risks, the pre-disposition of certain families and so on to play down tobacco-related risks."

So, strange as it may seem, increasing the amount of available knowledge may foster public ignorance. "In fact, those who seek to produce ignorance on a given topic generally advocate more research," says the science historian Peter Galison, of Harvard University. "The fact that all the details have not been resolved sustains the illusion of an ongoing debate on the whole subject. A key concern of American neocreationists is to 'Teach the controversy'."

But the media are partly to blame for disseminating this form of ignorance. "The media's deep-rooted concern for objectivity means that in any good presentation of an issue, there must be two contradictory points of view," Galison says. "But in some cases, not choosing actually means making a choice."

Proctor set up an experiment to gauge how well ideas put about by the tobacco industry permeated public opinion. In one of the many internal memos released by the industry at the end of the 1990s after a court ruling, he noticed that in 1975 executives at one large company instructed the public relations department to stop using the term "young smokers". Instead they had to say "young adult smokers". The historian set about searching for this phrase in the millions of books digitised by Google, taking account of their publication date. He found almost no instances of the term in any English-language publications before 1975. The phrase only started to spread after it was invented by the tobacco industry.

Strictly speaking, this was not an attempt to spread ignorance, but "it does enable us to measure the impact a simple internal memo can have on society as a whole," Proctor says. Even now, he adds, "about one in five Americans thinks that tobacco is not really dangerous". An even higher proportion is not convinced that passive smoking is harmful, despite there being ample documentary evidence of more than 500,000 premature deaths a year worldwide.

A famous internal memo issued by the US cigarette manufacturer Brown & Williamson put it bluntly: "Doubt is our product." The campaign by the tobacco industry to spread ignorance, which became a deliberate ploy in the 1950s, has since been copied in other fields.

"In the US a substantial share of the population – as many as half according to some studies – has the impression that there is a lot of debate in the scientific community as to the reality of climate change caused by human activities," says Naomi Oreskes, science historian at the University of California, San Diego, and the author, with Erik Conway, of Merchants of Doubt. "In 2004," she adds, "I published a study [an analysis of peer-reviewed scientific articles] which showed this was not the case. I immediately came under fire so I tried to find out who was attacking me." The historian soon discovered "a well-organised group of public figures who had claimed several years previously that acid rain and the hole in the ozone layer were not a problem".

Oreskes identified three well-known US scientists – William Nierenberg, Robert Jastrow and Frederick Seitz – who in 1984 had founded the George C Marshall Institute, a conservative thinktank, as a vehicle for their ideas. Seitz had also worked as a consultant for tobacco giant RJ Reynolds. "The connection with tobacco raised my suspicions," Oreskes says, "because it's a scientific field that has nothing to do with atmospheric science. It showed these people were engaged in a political project, not in genuine scientific debate on the issue of climate change."

The prime concern of the three men, according to the historian, was defending freedom. Even for distinguished academics, scientific facts may take second place to ideology, Oreskes says. "These scientists had founded their whole career on the use of science to defend the US against the Soviet Union. At the end of the cold war they took environmental science for another form of communism," she says. Which explains the link with tobacco. "Just as there is a fear of government regulating business, there is a genuine concern it may meddle in people's private lives, intervening in issues such as smoking."

In much the same vein as the Marshall Institute, many US thinktanks – often funded by fossil-fuel interests – have recruited scientists to carry on the work of obfuscation started in the 1980s and now targeting climate change. The methods are the same: publication of books, reports, press releases, columns in the press. "Their output looks like science, with footnotes and references but it does not take the usual channels," Oreskes says.

The advocates of ignorance have gained a new ally in the form of the internet. "Once arguments have been injected into the net, there is no stopping or countering them," says Oreskes.

This article originally appeared in Le Monde