John Stossel‘s latest column at Human Events highlights a favorite tactic among those who have no real arguments in political debates.

This week my TV show is on gun control. I interviewed activist Leah Barrett, who wants stricter gun laws.

I pointed out that after most states loosened gun laws to let people carry guns, 29 peer-reviewed studies examined the effect. Eighteen found less crime, 10 found no difference and only one found an increase.

“Which studies?” Barrett snapped. “John Lott’s? His research has been totally discredited.”

“Discredited” is a word the anti-gun activists use a lot. It’s as if they speak from the same playbook. …

… I may be biased here. One of Lott’s kids works for me. But when I look at the facts, I conclude that Lott is right. His critics, instead of arguing facts, smear. …

… Lott isn’t the only smear victim. Many academics who don’t toe the leftist line get attacked.

Climatologist Judith Curry was popular in academic circles when she assumed that global warming was a big problem. But then she looked deeper into the research and expressed some doubts.

Suddenly Curry was a “climate misinformer” who made “assertions unsupported by evidence” with “an irresponsible level of sloppiness.” Climate Progress founder Joe Romm wrote that Curry “abandons science.” Congressmen demanded that her university investigate her funding.

Curry told me that she only dared speak out against the leftist mob because she has tenure and is near retirement. Professors without tenure often lose jobs.

Lott was pushed out of Yale, Wharton and the University of Chicago. Now he runs a group called the Crime Prevention Research Center. To fend off smears, he refuses all funding from gun-makers.