The gun-control debate after the Dec. 14 massacre at Sandy Hook Elementary School in Connecticut has been mostly a non sequitur. Few of the reforms suggested would have prevented the shooting. But it is true that universal background checks, a more stringent mental-health reporting system and certain other measures could at least marginally reduce the frequency of mass shootings. It is also true — although Democrats are loath to admit it — that an armed and trained adult at Sandy Hook would have had a fighting chance of stopping Adam Lanza from killing 20 children and six staff members that day.

An important, and overlooked, fact of the Sandy Hook tragedy is that it took police 20 minutes to arrive at the school. The police are spread too thinly across many American communities to stop shootings in their first moments. And armed civilians have been instrumental in stopping shootings at New Life Church in Colorado, Pearl High School in Mississippi and elsewhere.

This hasn’t stopped some Democrats from arguing against armed self-defense. Some left-wing commentators, members of a class not previously known for its love of the police, think their fellow citizens don’t possess adequate faith that law enforcement will protect them.