Key to current Communist thought is that what many of us might call objective truth is, in fact, wholly subjective. Taking it one step further, the truth, for a Communist, is whatever the Communist leadership (aka "The Party") declares it to be. Since there is no objective, empirical truth, or, worse, since so-called objective, empirical truth is simply a scam by capitalists to keep themselves in power, The Party will define truth for us. And don't expect that truth to be logical, as pure logic is rarely of any use to the Party. It's simply too unreliable and capricious. And worse, it might be antagonistic to a Truth the Party has just declared.
If the Party says a toad is a dog, then it is a dog. Anyone arguing from evidence or empirical observation that a toad is a toad is immediately identifiable as an enemy of the Party. As an enemy of the Party, such an individual is immediately attacked by the Party and its minions, vilified, slandered, and, if possible, totally ruined in the eyes of the public which will then view such individuals not only as liars but as enemies of the Truth, which is, of course, whatever the Party says it is, which means that a toad is a dog. (If you doubt my word on this, follow the recent career trajectory of Sarah Palin.)
If anyone wants to truly understand how public manipulation has been conducted in the Western world over at least the last half-century, it's important to grasp this concept. It's what enables today's leftists to withstand and eventually triumph over the most withering of attacks. They simply don't recognize the standing of their attackers. They and their media backers denounce their opponents into oblivion--the 20th-21st century equivalent of book burning--and this dissent ultimately disappears from contemporary narrative.
Again, re: McCarthy. He's known today as a Communist Witch Hunter, which, in many ways he was. What no one seems to realize anymore is that Communist sympathizers and enemies of our government and way of life HAD infiltrated many of our institutions and DID (and still do) pose a danger to our way of life. Again, McCarthy simply could not have flourished as he did if there hadn't been at least some credible basis to his eventually out-of-control inquiries.
The universally-held myth of Joe McCarthy as 20th century America's villainous Witch Hunter General has now entirely obliterated the valid, initial reason for his Congressional investigations. His name has become an easy, convenient way to divert contemporary opponents of today's Communist flavors from pursuing any valid, rational inquiry on leftist endeavors. By immediately and unambiguously denouncing any opponent as a "McCarthyite," ideologues of the left quickly and permanently short-circuit dangerous inquiries and place said opponent permanently outside the circle of allegedly reliable people. (Again, witness the saga of Sarah Palin.)