Scepticism is one of the most important values in advanced societies. I’m glad Loretta Marron has it in spades. But like just about everything, you can have too much of a good thing, and Ms Marron proves this point with her burst of hypercynical colour-writing in last week’s item Quacks, charlatans and witch doctors: medical practitioners promoting alternative cancer cures.

I don’t doubt Ms Marron’s expertise or background as a scientist, or her award-winning cynicism. Nor do I take lightly her personal experience with cancer, which I wouldn’t wish on anyone. It’s obviously influenced her strident views, and I wish her well with her future health.

I too have seen the hokey lures of snake-oil merchants spruiking cancer cures. Our son was treated last year. We followed the conventional path, trusted the expertise of our doctors and had no regrets. But this same boy also has autism, and our experience with mainstream vs alternative medicine has been entirely different.

The medical establishment’s line is that the autism question is settled: it is a “brain disorder” or “developmental” abnormality with mainly genetic causes. It is accordingly a lifelong condition best “managed” with a range of behavioural therapies and social supports or aids.

But there is a growing movement — backed by numerous respected organisations, foundations, treatment centres, doctors and scientists — that question this so-called consensus. They argue that autism is in part a biochemical imbalance that is quite treatable. While genetic vulnerabilities play a part, environmental exposures are also major culprits, in particular vaccines and food allergies or intolerances.

We followed the second path and have seen some tremendous results. One of the main treatments we tried was “toxins removed by chelation”, so breathlessly mocked by Ms Marron in the context of cancer. We had our son’s hair tested by a US laboratory which had found an enormous excess of certain heavy metals, some of which are found in particular vaccines. The subsequent treatment involved taking supplements designed to gradually extract these toxins from his system.

Ms Marron claims that “hair, urine and blood analysis (sic) are ineffective for heavy metal and nutritional diagnostics”. These tests are scientific tests ordered by doctors and conducted in independent laboratories. Hair analysis is regularly used to determine if someone has a history of drug use, giving a timeline to toxin exposure much like age shows in tree rings. Doctors do blood analysis to see if a patient has anaemia or vitamin deficiencies (which can be life-threatening in severe cases).

While many disagree with the “alternative” position on autism, one cannot deny that it is supported by people with qualifications and is more than pure quackery. Not that some sceptics would believe it, or even tolerate the freedom of people to choose their own course. Many have launched themselves into this debate with a passion not seen at football matches. We have seen the “pffts” and disdain in doctors’ rooms, and (worse) the raving on the internet. Sadly, what should have been a purely medical issue has degenerated into the kind of politically-charged scrap that would make climate change cage-matchers blush.

It happens on both sides. Some in the mainstream medical community have reported receiving abusive phone calls and even death threats, simply for piping up in support of the orthodox studies. On either side, it’s a disgrace plain and simple. In the heat of the fight, kids are forgotten. There is only one important thing: to each find our own path to health rather than a right or wrong for everyone. Because there often isn’t one.

It’s all very well to have scepticism — it is our main line of defence against phonies. But you can take scepticism so far that you end up choking off any lines of inquiry that could lead to progress. People can use language to debunk anything, even if it means finding nothing. In the “mainstream” camp, many studies appear robust, but if they are framed around narrow terms of reference, if they set the burden of proof so high, if they look at 100 pieces of evidence but ignore another 1000, or simply ask the wrong questions, what use are the answers?

I think what’s missing from Ms Marron’s article is a distinction between doctors who practice the best alternative therapies because they recognise the shortfalls of mainstream medicine and someone opening a “crystal healing clinic” in their back room.

A medical “canon” is essential. But canons evolve and are challenged. Many advances in our society, including medical breakthroughs, are often only possible when a renegade dares to buck orthodoxy. For how long did Big Tobacco wield medical and scientific expertise to bolster its credibility? For how long were various mental illnesses treated as “madness” before common medical treatments demystified them?

If Ms Marron wished to study the autism wars, she could turn that same brilliant, white-hot blowtorch of scepticism onto the well-resourced, PR-buttressed medical establishment, and its close cousin Big Pharma. Of all the hundreds of studies disproving a link between autism and vaccines, few are independent of these two industries. While this doesn’t always undermine the integrity of the studies, isn’t it worth a glimpse of the sceptic’s probing eye?

Autism rates have gone from 1 in 10,000 to 1 in 150 in about 30 years. Countries with different vaccine schedules, eg Sweden, Italy and Denmark, have much lower rates of autism. Surely we must ask why?

It seems scepticism, even in its strongest and most elemental form, can be selective.