BRYAN CAPLAN: “Valkyrie, Bryan Singer’s film about the 1944 officers’ plot against Hitler, is worth seeing. But I’m admittedly a little biased. After all, my first academic publication (in the Humane Studies Review) has a whole section on the philosophy of tyrannicide. In hindsight, I’m amazed that people who don’t think twice about killing conscripts (or even civilians) are so reluctant to justify violence against serial killer statesmen. What could be less objectionable than trying to stop mass murder by killing the specific individuals most responsible for it?” What, indeed?