The substitution of mere suspicion for evidence seems to color the thinking of many -- on Iraq (as the Suskind book amply documents), on fiscal policy and on science as well. From stem cells to creation science, from illegal wiretaps to war planning, if it feels good and accords with ideology, then it's the right thing to do. Real men don't need evidence or probability.
Nor do they need consistency. A companion to the Cheney 1 percent action doctrine (if the probability is at least 1 percent, act) is the administration's non-action doctrine (if the probability is less than 99 percent, then don't act). This latter doctrine is generally invoked in discussions of global warming, where it seems absolute certainty is required to justify any significant action. Ideology determines which of these two inconsistent doctrines to invoke.
Of course, these attitudes and variations of these doctrines are very widespread throughout society, and it's sometimes very difficult to decide whether to act or not. In fact, it's an interesting exercise to come up with other situations leading to rules of the form, "if the probability is X percent, then act." Surprisingly many of the everyday rules guiding us can be put into this form.
A trivial example is provided by elections where X percent is 50 percent, but let me end with a somewhat unusual and counterintuitive example, which involves an idealization of the dating process. Say that a woman has reason to believe she will have up to N sequential suitors during her dating life and wants to maximize her chances of choosing the "best" one. The optimal strategy she should follow is to reject the first 37 percent of her suitors and then accept the next one who is better than all his predecessors.
Whether the issue is war, science, or a myriad of other issues, probability and evidence should play a critical role.
Professor of mathematics at Temple University, John Allen Paulos is the author of best-selling books including "Innumeracy" and "A Mathematician Plays the Stock Market." His "Who's Counting?" column on ABCNews.com appears the first weekend of every month.