Propaganda campaigns often acquire a life of their own. Politicians who have hitched their wagons to the star of "global warming" cannot admit any doubts on their part, or permit any doubts by others from becoming part of a public debate.

Neither can environmental crusaders, whose whole sense of themselves as saviors of the planet is at stake, as they try to stamp out any views to the contrary.

A recent and revealing example of the ruthless attempts to silence anyone who dares question the global warming crusade began with a "news" story in the British newspaper "The Guardian." It quickly found an echo among American Senators on the left -- Bernard Sanders, an avowed socialist, and John Kerry, Pat Leahy and Dianne Feinstein, who are unavowed.

The headline of the "news" story said it all: "Scientists Offered Cash to Dispute Climate Study." According to "The Guardian," scientists and economists "have been offered $10,000 each by a lobby group funded by one of the world's largest oil companies to undermine a major climate change report."

It is a classic notion on the left in general, and of environmentalist zealots in particular, that no one can disagree with them unless they are either uninformed or dishonest. Here they dispose of scientists who are skeptical of the global warming hysteria by depicting them as being bribed by lobbyists for the oil companies.

While such charges may be enough for crusading zealots to wrap themselves ever more tightly in the mantle of virtue, some of us are still old-fashioned enough to want to know the actual facts.

In this case, the fact is that the American Enterprise Institute -- a think tank, not a lobbyist -- did what all kinds of think tanks do, all across the political spectrum, all across the country, and all around the world.

AEI has planned a roundtable discussion of global warming, attended by people with differing views on the subject. That was their fundamental sin, in the eyes of the global warming crowd. They treated this as an issue, rather than a dogma.

Like liberal, conservative, and other think tanks, the American Enterprise Institute pays people who do the work of preparing scholarly papers for presentation at its roundtables. Ten thousand dollars is not an unusual amount and many have received more from other think tanks for similar work.

Enter Senators Sanders, Kerry, Leahy, and Feinstein. In a joint letter to the head of the American Enterprise Institute, they express shock, shock, like the corrupt police official in "Casablanca." Continued...