Exhibit A:

“There is no experimental data to support the hypothesis that smoking causes lung cancer, chronic obstructive pulmonary disease, emphysema, or chronic bronchitis………any number of things can influence the onset of a disease. The list includes genetics, diet, workplace environment, and stress…….we understand public anxiety about smoking causing disease, but are concerned that many of these much-publicized associations are ill-informed and misleading……….the media continue to uncritically accept and vigorously promote an anti-smoking agenda…….after hundreds of millions of dollars spent on clinical research, and decades of screaming headlines, we have no more certainty today about smoking causing disease than we did decades ago……….if even a small part of the time and money spent trying to link smoking to cancer were spent instead on studying the other causes of cancer, millions of lives could be saved.”

Exhibit B:

“The claim that human activities cause climate change has not been scientifically proven……….it is a reductionist error and not keeping with the current theories of climate science to attempt  to assign each temperature change to an exclusive single cause………..the use of results from flawed computer models to frighten people by attributing catastrophic future change to current human activities may be misleading and is highly regrettable……..that emotionalism can override objective analysis is illustrated by the headlines………..despite millions of dollars spent by the government on climate modeling and research, many questions about the relationship between human activities and global temperature change remain unanswered……….indeed, many scientists are becoming concerned that preoccupation with anthropogenic global warming may be both unfounded and dangerous – unfounded because evidence on many critical points is conflicting, dangerous because it diverts attention from other suspected hazards.”

Now read the originals.

Exhibit A

“There is no experimental data to support the hypothesis that increases in hydrocarbon use or in atmospheric carbon dioxide and other greenhouse gases are causing or can be expected to cause unfavourable changes in global temperatures, weather, or landscape…….any number of things can influence earth’s temperature. The list includes volcanic eruptions, variations in the amount of energy received from the sun, El Niños, and La Niñas – all of which are natural………we understand public anxiety about climate change, but are concerned that many of these much publicized predictions are ill-informed and misleading……….the media continue to uncritically accept and vigorously promote shrill global warming alarmism………after hundreds of millions of dollars spent on climate modeling, and decades of screaming headlines, we have no more certainty today about global warming prediction than we did decades ago………..if even a small part of the money spent trying to reduce carbon dioxide emissions were spent instead on fighting hunger or disease in Third World countries, millions of lives could be saved.”

-from the various articles on the Heartland Institute’s global warming page

Exhibit B

“The claim that cigarette smoking causes lung cancer has not been scientifically proven………..it is a reductionist error and not keeping with the current theories of cancer causation to attempt to assign each cancer to an exclusive single cause…………the use of results from flawed population studies to frighten people by attributing large numbers of death yearly to smoking may be misleading and is most regrettable……….that emotionalism can override objective analysis is illustrated by the headlines………despite millions of dollars spent by the government on smoking and health-related research, many questions about the relationship between smoking and disease remain unanswered…………indeed, many scientists are becoming concerned that preoccupation with smoking may be both unfounded and dangerous – unfounded because evidence on many critical points is conflicting, dangerous because it diverts attention from other suspected hazards.”

-from Smoking and Health: 1964-1979: The Continuing Controversy, published in 1979 by the Tobacco Institute

If I hadn’t told you which set of quotes was unchanged, and which I had replaced words like “smoking” and “cancer” with “human activities” and “climate change”, or vice versa, would you even have known the difference?