Every day, people make decisions that involve potential harm to others. Though these decisions are central to our moral lives, little is known about how they are influenced by a key psychological process: episodic simulation. Several psychological theories predict that imagining harming others, which people typically find aversive, would dissuade them from harming. Here, however, we find the opposite: Imagining harming others increases the perceived likelihood of performing that harm in the future. This effect arises because people spontaneously construct moral justifications for the harm, which engender positive feelings about harming. Our results contribute to a growing body of evidence that harming others is often cast in a positive light.