Once upon a different time the communists and their fellow travelers had a simple slogan and strategy: No enemies to the left!

It sounds better in French – pas d'ennemis à gauche – not just because so many things do, but because the concept originated with the French, and explains why their intellectual life can be both so rich and so mistaken. Sometimes fatally. Why? Because those who are willing to sacrifice enduring principle or even elemental decency for a transient political alliance may find themselves the first put up against the wall.

See Petrograd, 1917. Or maybe, soon enough, Cairo, 2011. The bright dawn of revolution has a way of fading stage by stage to black repression. It is a dangerous calling, being a foil for some small but well-organized conspiracy, whether Communist, Fascist or Islamist.

No enemies to the left! It was the motto of every rebirth of the Popular Front in Europe, and isn’t unknown in this country. See the misadventure that was Henry Wallace’s presidential campaign in 1948; his Progressive Party had to be strangest assortment of mixed species since Noah’s Ark – its youthful idealists marching side by side with cynical old veterans of The Party.

As for Henry Wallace, who was the very soul of naivete, he deluded no one that year more than himself, for he would prove more pawn than player. But progressive, enlightened, well-indoctrinated American progressives weren’t about to recognize any enemies to the left.

A mirror image of the same, fatal illusion can be found on the right. So long as those rousing the rabble are doing it in a supposedly conservative cause, they mustn’t be criticized. It’s considered a kind of ideological treason to point out their flaws. I know. I’ve tried – and I’ve got the angry e-mails to show for it.

Just try noting Bill O'Reilly’s closed mind, or Glenn Beck’s tendency to substitute rant for reason, and stand back for the irate reactions. (“I generally admire your columns, but …”) Even those of my valued correspondents on the right who recognize that the El Rushbos and Ann Coulters are demagogues of the more vulgar sort don’t much like to be reminded of it.

It’s no coincidence that Ms. Coulter should have written a defense of Joe McCarthy, or that it was as wrong-headed as he was. But even if the Limbaughs and Coulters are demagogues, dammit, they’re our demagogues. No enemies to the right!

Even the best and ordinarily most honest and thoughtful of conservatives can make the same, dangerous mistake. The late great Robert A. Taft, Mr. Integrity himself, might privately describe Joe McCarthy’s wild charges as nonsense but play along with Tail-Gunner Joe anyway. (“If one case doesn’t work out, just bring up another.”)

Sen. Taft may have thought he was using McCarthy, but it was McCarthy who was using him – and his respectability. Just as today a respected scholar and thinker on the right like Wilfred McClay will write an apologia for Rush Limbaugh in Commentary. No enemies to the right! The man may be a boor, but he’s our boor!

Whittaker Chambers knew better. The old anticommunist (and, before that, communist) knew the dangers of entrusting a great cause to brutish minds and raucous radio voices. He would warn William F. Buckley about supporting the junior senator and demagogue from Wisconsin after young Buckley had used his precocious intellect to make excuses for McCarthy.

“All of us,” Whittaker Chambers wrote Bill Buckley, “would like to be his partisans, if only because all are engaged in the same war. As it is, most of us make an effort to overlook certain matters or to give him the benefit of the doubt of most doubts. But, all of us, to one degree or another, have slowly come to question his judgment and to fear acutely that his flair for the sensational, his inaccuracies and distortions, his tendency to sacrifice the greater objective for the momentary effect, will lead him and us into trouble. In fact, it is no exaggeration to say that we live in terror that Sen. McCarthy will one day make some irreparable blunder which will play directly into the hands of our common enemy and discredit the whole anticommunist effort for a long time to come.”

Which is just what happened with the Army-McCarthy hearings. McCarthyism would become the bane of the whole anticommunist effort for a long time to come. Just as the Limbaughs and Becks, O'Reillys and Coulters, now threaten to make a caricature of conservatism.

Dare point out that danger and you’ll be told, in effect, no enemies to the right! Even if you disagree with their means, you’ll be told you ought to recognize that their ends are the same as ours. (Just as Joe McCarthy’s were?) That kind of dangerous simplification overlooks how easily means come to replace ends.

The moral of the story: Style is not an optional feature when it comes to ideas; it is of the essence. And when high-minded ends are pursued through low ends, it’s not the ends that may win out. See the example of Joe McCarthy. It is an example not to follow but to beware.

© 2011 TRIBUNE MEDIA SERVICES, INC.