In a world where down is up and up is down, celebrity blowhard Jenny McCarthy has somehow emerged as an underdog fighting for the little guy.

Her target: the vaccines she mistakenly believes cause autism.

Her pulpit: the highest-rated daytime talk show on TV, where she will replace Elisabeth Hasselbeck as co-host of The View in September.

The result: her power to influence the masses has just increased by the power of infinity.

The question, of course, is whether or not this is a good thing.

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From McCarthy’s point of view, it’s a major victory in her battle to get her message out: vaccines are bad and autism can be cured, if you just ignore the scientists and sawbones who insist on pesky factual data.

It’s David vs. Goliath, Warrior Mom vs. Stuffed Shirt Medical Establishment, New Age Rebel vs. The Man.

Ah, but there’s another side: those who value facts over opinions and view McCarthy as a fear mongering dimwit whose sanctimonious crusade, however well-intentioned, threatens to turn the clock back on medical science.

Given that measles and whooping cough have already staged a comeback as parents panic and vaccination rates drop, it’s also potentially dangerous.

To be clear, there is no medical evidence to support her assertion — based on a discredited study — that vaccines cause autism, no evidence that the alternative treatments she promotes will have any positive effect on this ballooning developmental disorder and no evidence that her own son was, as she insists, “cured” of autism (the diagnosis has been disputed by experts).

Which is why Toronto Public Health has launched a campaign to get the 40-year-old muckraker fired from her high-profile TV posting.

“Jenny McCarthy’s anti-vaccine views = misinformation,” the agency wrote on Twitter. “She cites fraudulent research on vaccines and it’s irresponsible to provide her with The View platform.”

Overreaction?

People trust celebrities, no matter how stupid or ill-informed, and look to them for advice.

And parents of autistic children are more vulnerable than most.

I know, because I’m one of them.

When my son Max, now 5, was diagnosed with the complex brain disorder just after his third birthday, it was like a sucker punch to the gut.

In one bracing instant, the dreams I’d nursed since his conception went up in smoke, landing my wife and I somewhere in The Twilight Zone .

Forget about little league, rock superstardom and flinging pithy bon mots at the dinner table (note: this last one was never going to happen anyway).

What became immediately clear was that, at least in the short term, the majority of our time would be spent chauffeuring our son to specialists and therapy groups, advocating on his behalf to school officials and attending parental support groups to figure out which end is up.

Overwhelming? That’s not the half of it.

Had someone approached me at that precise moment and offered a magic pill to take away Max’s autism-related issues — the volcanic meltdowns, the testy inflexibility — would I have considered it?

My wife and I have this discussion, however hypothetical, all the time.

She says no, because Max — a sweet kid with a probing, curious intelligence — is the sum of his quirks, and to alter his fundamental DNA would change the essence of who he is.

There’s nothing “wrong” with him: his brain is just wired differently.

I agree, but I would still go for the pill, because as far as I’m concerned, Max is Max, autistic or not, and anything that’s going to make his life less challenging and easier to navigate is fine with me.

The one thing we do agree on — and this supersedes any New Age flakiness on my part — is that McCarthy is a quack, the Honey Boo Boo of autism awareness, a vainglorious hustler with no medical background who relies on what she refers to as her “mommy instinct,” even when it flies in the face of scientific facts.

It’s Snooki pontificating on the origins of the universe, Kim Kardashian lecturing NASA about nuclear fission.

“The University of Google is where I got my degree,” the former Playboy pin-up boasted to Oprah Winfrey, flaunting her ignorance as a sign of authenticity.

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This, keep in mind, is a woman who considers spoons rubbed on the body a viable autism treatment.

I’m not impugning her integrity or devotion to the cause.

I’m impugning the brand of “belligerent ignorance” she preaches so dramatically on the world stage.

But much as I’d like to, I can’t lay it all at her feet.

Much of the problem lies with a celebrity-obsessed media who stubbornly insist on presenting two sides to every issue, even when this clearly makes no sense.

False equivalence, writer Mark Hertsgaard calls it, and it’s the cardinal sin of journalism.

Did the Holocaust really happen? Let’s get representatives from both sides to argue their case.

Does smoking cause cancer? Let’s get a doctor and tobacco CEO to debate this contentious issue.

Do vaccines cause autism? The entire medical establishment and scientific community say no, but Jenny McCarthy, a former Playboy model who believes in hyperbaric oxygen chambers and the existence of paranormally gifted “crystal children,” says yes.

Let’s give her a public soapbox and let the debate begin.

This is what The View is doing by making her a co-host: giving her fringe views a credibility they don’t warrant.

And it’s telling that, as of press time, the show’s producers have yet to respond to the growing outrage over her hiring.

Because really, what can they say? “We know we’re being irresponsible, that she’s a flake, but this is a ratings move and a polarizing figure like McCarthy is the best way to stoke controversy.”?

Make no mistake: McCarthy offers hope, which is one thing the medical establishment can’t, because at this moment, autism has no known cause or cure.

But it’s false hope, the kind that can lead to foolish decisions, exhausted bank accounts and, if you buy her anti-vax rhetoric, a lot of needless suffering.

As for miracle cures, 22 months after Max’s mild-to-moderate diagnosis, I’m no longer convinced they’re even necessary.

I don’t want to underplay his challenges: he still struggles, despite a raft of medically sanctioned behavioural therapies, and his social communication and sensory issues aren’t going away any time soon.

But he just finished a wildly successful year in junior kindergarten, he’s having the time of his life at art, music and gymnastics camps, and the stereotypical quirks that once defined his personality are gradually giving way to a thoughtful, if quirky 5-year-old in awe of the world around him.

No laying on of spoons or invasive blood detoxes required.

Correction: July 30, 2013 : This article was edited from a previous version that mistakenly included a statement attributed to Jenny McCarthy that she never actually said. The statement: "Think of autism as a fart and vaccines are the finger you pull to make it happen" was made up by a website called The Superficial.