M.D. Harmon’s April 4 column, “ ‘More guns, less crime’ just got proved all over again,” cites a scholarly article published in the most recent issue of the journal Applied Economics Letters.

Harmon quotes the article’s author, Professor Mark Gius, in support of Harmon’s well-known views on the Second Amendment. What Mr. Harmon does not tell us is that Gius’ statistical analysis identified a number of other variables that explained more of the variation in state-level murder rates than did restrictive concealed-carry laws.

In contrast to Harmon’s column, Professor Gius’ research is a work of empirical social science, not political ideology. Explaining the effect of concealed-carry laws is no simple thing, as Gius makes clear to anyone bothering to read beyond the article’s abstract. Informative and carefully executed as Professor Gius’ research is, it “proves” nothing. What it does do is add to the body of empirical research on the impact of our patchwork of gun laws – research that Gius admits is mixed and even contradictory.

Finally, if more guns mean less crime (as Harmon asserts), how might he explain the most recent mass shooting at what has to be one of the more well-armed and heavily fortified places in America (Fort Hood) in a state (Texas) that has arguably the least restrictive gun laws in the country?