Erik M. Conway is a historian of science and technology. Naomi Oreskes is a professor of history and science studies at the University of California at San Diego. They are the authors of Merchants of Doubt (Bloomsbury, 201­0).

A prediction: When all the votes have been counted and the reams of polling data have been crunched, analyzed, and spun, this will be clear: Few scientists will have voted for Republican candidates, particularly for national office. Survey data taken from 1974 through 2010 and analyzed by Gordon Gauchat in the American Sociological Review confirm that most American scientists are not conservatives. A 2009 study by the Pew Research Center found that only 9 percent of scientists self-identified as conservative, while 52 percent called themselves liberals. Only 6 percent of American scientists self-identified as Republicans. This state of affairs is bad for the nation, and bad for science.

It was not always this way. In the 1968 election, Richard Nixon won the votes of 31 percent of physicists, 42 percent of biologists, 52 percent of geologists, and 62 percent of agricultural scientists (compared with 43.4 percent of the popular vote). While these data do not include party affiliation, they suggest that the scientific community of the late 1960s was much more evenly divided between the two major parties than it is now, and, with the exception of physicists, slightly more conservative than the American voting public at large.

Why have scientists fled the Republican Party? The obvious answer is that the Republican Party has spurned science....