The old refrain of "We must do something" has a new corollary affixed to it: "After all, we did something after 9/11."

I cannot imagine a worse argument for any policy. Yet in the wake of the massacre in Las Vegas, some high-profile people have embraced this idea like it's a revelation.

"When planes flew into the World Trade Center, did we say now is not the time to talk about terrorism?" asked Meet the Press host Chuck Todd. We didn't, but maybe we should have. Todd has apparently forgotten that the product of that post-9/11 talk about terrorism was a war on terror that has left Americans less free and the world less safe.

The Bush administration used the heightened emotions following the 9/11 attack to push through the PATRIOT Act and the 2001 Authorization for Use of Military Force. The former expanded government power at the expense of individual rights while casting a net so wide as to make it useless for any real counterterrorism effort. The latter was used to launch not just the war in Afghanistan but, since then, several military actions across the Muslim world with little if any connection to 9/11.

Both should be cautionary tales about making policy in the immediate wake of tragedy. Neither is an example to emulate.

Kal Penn, an actor who worked on public outreach for the Obama White House, trotted out the same comparison. "Americans killed on 9/11: 2,996. Days it took Congress to authorize war: 3," he tweeted. "Americans killed by guns in 2017: 11,652. Days in 2017 so far: 275." Is Penn unaware of what a failure the Afghan war has been? Let alone all the other wars Washington has waged under the same Authorization for Use of Military Force?

Then there's late-night comedian Jimmy Kimmel. "When someone with a beard attacks us, we tap phones, we invoke travel bans, we build walls, we take every possible precaution to make sure it doesn't happen again," Kimmel said Monday night. "But when an American buys a gun and kills other Americans, then there's nothing we can about that." Since Kimmel is explicitly opposed to Trump's travel ban and some of the other policies he mentioned, it's not clear why he thinks he's making a compelling argument.

Meanwhile, gun restrictions passed in the aftermath of previous mass shootings, like Newtown, tend to be ineffective at best and violations of civil liberties at worst. It's almost as though there's a good reason to be wary of laws rushed into place right after a tragedy hits the news.