If the definition of insanity is doing the same thing over and over again while expecting a different outcome, then Donald J. Trump is curing insanity in American politics.

Which is kind of funny when you consider how bat-chip crazy so many people have gone over the past four weeks. Ranting and raving about leaving the country. Canceling Christmas parties. Branjelina breaking up.

In Washington, political zombies fill the streets, wandering aimlessly in tattered clothes they haven’t changed in weeks. Eyes are like throbbing bull’s-eyes. Stumbling. Excessively medicated.

I tossed an empty coffee cup into a city trash can on Capitol Hill the other day and a woman in a trench coat and carrying a briefcase came charging down the sidewalk at me with a wild, distraught look on her face.

“No!!!!” she cried, grabbing the trash can. “That is MY trash can! You can’t do that! What are you doing?” She was on the verge of tears. May have been actually crying. Clearly not among the army of voters eager to Make America Great Again.

Retired Marine Gen. Jim “Mad Dog” Mattis, on the other hand, is willing to serve.

A fearsome warrior, Gen. Mattis is a big, strategic thinker who has studied America, civilians, and soldiers over the past decade and a half of constant war — the longest such span in American history. When there is a yawning disconnect between the tiny fraction of Americans who serve in the military and the vast sea of civilians who enjoy the freedoms thereby secured, serious problems arise.

When civilians in Congress have a casual tendency to launch wars they later lose interest in (see: John Kerry, Hillary Clinton, Harry Reid), then we have a serious problem.

Weak politicians change their minds and then move on to their next whorish exploit. Soldiers lose their legs or their lives or their minds and they don’t get to move on.

This is the single most pressing concern of our federal government today.

Gen. Mattis also never loses sight of the explicit purpose of our military: To find the enemy and kill them swiftly and ferociously. “Do not cross us,” he once explained of his Marines. “Because if you do, the survivors will write about what we do here for 10,000 years.”

That is what you call a firm grasp of the particulars while never losing the big picture.

Gays in the military? Women in combat? Gen. Mattis has only one reply. Does it increase the lethality of our fighting troops?

Of course, the Masters of Insanity in Washington are just fine doing the same thing over and over again. The dirty secret is that they don’t even want a different result. They like things just fine.

These people will do everything in their power to stop Gen. Mattis. They are the same ones already carping about retired brain surgeon Ben Carson’s being picked to run the Department of Housing and Urban Development.

He doesn’t have experience running such a massive bureaucracy! He does not have a background in federal welfare programs!

Well, he grew up in poverty in Detroit and became a brain surgeon. Sounds like the right experience to me.

Anyway, if a guy as smart and decent and dedicated as Mr. Carson cannot get a handle on HUD, then that doesn’t mean there is something wrong with Mr. Carson. That means something is wrong with HUD. And it is high time HUD got zapped into shape.

• Charles Hurt can be reached at charleshurt@live.com; follow him on Twitter via @charleshurt.