Science journalists certainly don't always get the facts right. Eighty-nine percent of scientists surveyed expressed "only some" or "hardly any" confidence in the press, according to a 1997 study by the First Amendment Center. "It Ain't Necessarily So" makes a few valid points. Too often, journalists opt for covering sensationalistic stories -- like the one about the asteroid that, at least until more complete calculations were revealed the following day, was headed straight for Earth -- instead of the really important, hard-edged ones that readers find less interesting. Every newspaper has its editorial slant, and that does indeed determine its choice of which stories to cover and which to leave behind. The authors of "It Ain't Necessarily So" take particular delight, of course, in lashing at the New York Times and the Washington Post.

But the hypocrisy of "It Ain't Necessarily So" is that it employs the very same tactics that it finds so objectionable when used by journalists and publishers. Consider their criticism of coverage of Camille Parmesan's study of the extinction rates of local populations of a western butterfly, the Edith's checkerspot, due to global warming. Parmesan's work, one of the first solid pieces of evidence of the biological effects of global warming, was published in the journal Nature in 1996.

As is the case with so many examples in this book, the authors' criticism of how journalists covered the story quickly becomes criticism of the original study itself. One of their techniques is to omit mention of any findings that do not support their agenda. Complaining that Parmesan "took it for granted that the climate had warmed in locales in which the checkerspot was now extinct," they quote a 1996 communication in the Bulletin of the American Meteorological Society (BAMS) saying that the "apparent 'global warming'" in the western U.S. "is in reality urban waste heat affecting only urban areas."

But this analysis doesn't hold up under closer scrutiny. Not only is the BAMS paper that the authors of "It Ain't Necessarily So" cite a simplistic statistical view of the measurement of urban heating -- tallying county-by-county information regardless of the vagaries of individual temperature measuring stations -- but they also overlook a major BAMS paper published earlier that same year by Thomas Karl and colleagues of the National Climatic Data Center. This study found a 1 to 3 degree Celsius warming in the western United States from 1910 to 1995 -- after explicitly correcting for urban heat island effects.

Likewise the authors grouse that Parmesan did not take into consideration that the thinning of the butterflies' population may have result from the loss of their host plants due to factors such as changes in air quality or the impact of agricultural chemicals. But Parmesan, as expected, does state -- in a figure caption -- that she did not count checkerspots in sites that "were degraded by loss of usable host plants," regardless of the reasons for that loss. She also writers that she had eliminated over three-quarters of the sites potentially available to her for, in part, just such reasons of degradation.

Other criticisms in "It Ain't Necessarily So" are just wrong. The authors complain that Parmesan did not include "anything like a baseline for the number of extinctions that would be expected in the absence of any warming." But what they apparently fail to understand is that Parmesan designed her study to reveal patterns of net extinction with respect to latitude, rather than the absolute number of extinctions. It is these patterns that were the signal that population changes were due to climate change. Furthermore, the authors misread a reference to "2 degrees" as one of temperature ("Celsius"), and not of latitude -- which is just the kind of error you might expect from social scientists dissecting a study in the natural sciences.

Finally, other criticisms in "It Ain't Necessarily So" are simply petty. They denigrate Parmesan's study because it made claims about a single species of butterfly, ignoring follow-up studies by Parmesan, David R. Easterling and others, some of which found similar shifts in 57 species of butterflies in Europe. They sneer that the New York Times article on Parmesan's work was "lengthier, in fact, than [Parmesan's] study itself," as if properly explaining a piece of complex work to nonscientific readers should be more dense than the specialized language of the scientists. And they refer to Parmesan's work as "preliminary," as if Nature weren't one of the most prestigious peer-reviewed scientific journals in the world.

Such disingenuous maneuvers fill "It Ain't Necessarily So." It's clear that while the authors are good at looking up articles in Lexis-Nexis, they aren't playing straight with their readers. Even when Murray and his colleagues hit the occasional right note, it's always from the same tune. Their analyses and conclusions inevitably stack up in favor of the view that there are few environmental problems that less government spending won't fix and that social dilemmas like racial discrimination are figments of overactive imagination. A fair review of the state of science journalism is always welcome, but this cleverly disguised example of corporate propaganda isn't it.

Maya Angelou reads from "The Heart of a Woman"