I argue that the Doctrine of Double Effect is accepted because of unreliable processes of belief-formation, making it unacceptably likely to be mistaken. We accept the doctrine because we more vividly imagine intended consequences of our actions than merely foreseen ones, making our aversions to the intended harms more violent, and making us judge that producing the intended harms is morally worse. This explanation fits psychological evidence from Schnall and others, and recent neuroscientific research from Greene, Klein, Kahane, and Schaich (...) Borg. It explains Mikhail and Hauser’s “universal moral grammar” and an interesting phenomenon about Double Effect cases noted by Bennett. When unequally vivid representations determine our decisions, we typically misjudge the merits of our options and make mistakes. So if Double Effect is a product of unequal vividness, it is likely to be mistaken. This argument, I claim, fits Berker’s specifications for good empirically grounded arguments in ethics. (shrink)