"Stop saying it's complicated!" The liberal playbook in the aftermath of any mass shooting works like this: The left, usually taking it cue from President Obama, declares that we once again have all the proof we need that we need to ban guns (except that they phrase it as “common-sense gun safety laws”), and that any argument to the contrary is self-evidently a refusal to solve the problem of gun violence, which is obviously the result of politicians’ fear of the NRA or some sort of cultish devotion to the Second Amendment. What is supposed to happen is that the...