Doubt is crucial to science — in the version we call curiosity or healthy skepticism, it drives science forward — but it also makes science vulnerable to misrepresentation, because it is easy to take uncertainties out of context and create the impression that everything is unresolved. This was the tobacco industry’s key insight: that you could use normal scientific uncertainty to undermine the status of actual scientific knowledge. As in jujitsu, you could use science against itself. “Doubt is our product,” ran the infamous memo written by one tobacco industry executive in 1969, “since it is the best means of competing with the ‘body of fact’ that exists in the minds of the general public.” The industry defended its primary product — tobacco — by manufacturing something else: doubt about its harm. “No proof” became a mantra that they would use again in the 1990s when attention turned to secondhand smoke. It also became the mantra of nearly every campaign in the last quarter of the century to fight facts.

For tobacco is not the end of our story. It is just the beginning. In the years to come various groups and individuals began to challenge scientific evidence that threatened their commercial interests or ideological beliefs. Many of these campaigns involved the strategies developed by the tobacco industry, and some of them involved the same people.

—Naomi Oreskes & Eric M Conway
Merchants of Doubt