In an appearance on Fox News Sunday, Rudy Giuliani complained that the mainstream media is covering up evidence that Hillary Clinton suffers a severe and undisclosed medical condition that renders her unfit to serve as president.

His evidence for that extremely serious charge? Videos on the Internet:

"... all you gotta do is go online. Go online and put down 'Hillary Clinton illness,' take a look at the videos yourself."

Of course, among other things that videos on the Internet will teach you are:

There was a time in the not-too-distant past when presidential candidates and their surrogates would have been too ashamed to publicly push such nonsense. No longer. In the era of Trump, the concept of shame and self-respect as limiting factors has disappeared, and there are now no depths to which certain people will not sink, even in defense of a doomed candidate.

And to be fair, it's not all Donald Trump's fault, because the phenomenon long predates his political career. In fact, this "Hillary is dying" meme is to the 2016 campaign against Clinton what birtherism had been to the GOP's never-ending campaign against Barack Obama:

1.) It shares the same basis in fact, which is none.  It is a conspiracy theory hatched in the fetid Internet swamps, then embraced, given credibility and repeated by those who find it useful without regard to its truthfulness. In a strange way, its utter lack of factuality makes it immune to being disproved on a factual basis. (Case in point: Sean Hannity and others had alleged that Clinton's security detail had been spotted carrying a diazepam syringe, used "for patients who experience recurrent seizures." As a Secret Service spokeswoman later confirmed, it was actually a small flashlight.)

2.) It also serves the same functions as birtherism, which are to delegitimize its intended target, provide programming for the conservative entertainment complex and give the base a talking point to recite endlessly among each other. As Giuliani suggests, when the mainstream media refuse to give such allegations credence -- because they have none -- that's yet another bonus, confirming the media's bias against conservatives.

3.) Like birtherism, it serves as a bizarre, cult-like test of loyalty to the movement. Psychologists have long observed a phenomenon described as "groupthink", defined originally by Yale psychologist Irving Janis. He defines it as “a mode of thinking that people engage in when they are deeply involved in a cohesive group, when the members’ striving for unanimity overrides their motivation to realistically appraise alternative courses of action.... Groupthink refers to a deterioration of mental efficiencies, reality testing, and moral judgment that results from in-group pressures”. That describes it perfectly. Even now, in a recent NBC News poll, only 27 percent of Republicans would admit that Obama was born in this country, because they have been taught that believing the unbelievable is preferable to individual thought that risks group conformity.  The same is proving true of this "dying Hillary" meme.

4.) As we saw during the Republican convention, groupthink that may sound convincing to those self-confined within the GOP echo chamber sounds like obsessive crazy talk when it's uttered in the world at large, where facts are still somewhat respected and skepticism is still allowed. The long string of conspiracy theories that have taken root within the GOP, from "Hillary murdered Vince Foster" through "Obama is an America-hating Muslim" to the current "Hillary is dying," makes it difficult to conceive of the party as responsible and capable of governance.

The emphasis placed on such nonsense also makes it hard for the public to distinguish between such fiction and GOP critiques that do have some legitimacy, such as questions about the Clinton Foundation's fundraising. The credibility needed to make that latter, legitimate argument is squandered by the insistence on peddling this kind of groundless stuff that the right has come to rely upon much too heavily.