Government, where decisions made in a moment can affect millions of people for a lifetime, needs constant reminders of its fallibility. A big part of that has to be a proper respect for the methods of science, as well as for its substantive discoveries. Psychologists assure us that human beings have a strong desire to accept things as true because we want them to be true, not only because they are the best explanation for what we observe. In the hands of policy-makers, that natural tendency can have deadly consequences. Science has developed impressive (though not infallible) techniques for correcting for such biases; our government could stand to do a bit better.