Meryl Dorey and the Fallacy of the Excluded Middle

Meryl Dorey, of the ever-inaccurately named Australian Vaccination Network, tweets this gem every so often from scheduled tweet service SocialOomph:

Meryl skirts close to the shining star of truth in order to gain escape velocity for her long spaceflight to the nebula of fail

Taken purely at face value, this tweet is almost true. Almost.

You could almost imagine a similar version coming from a competent immunologist. "No vaccination is 100% effective 100% of the time. Even after you receive a vaccination, there may be circumstances in which you could develop a symptomatic infection".

Thing is, that's not what Meryl is trying to get across, as you'll see from this screen cap of an email from Meryl herself:

Dastardly, Meryl? When does Muttley arrive?

 Yes, Meryl really seems to believe, and has repeated on many occasions, that if a vaccine is not 100% effective, then it doesn't work at all.

This is the fallacy of the excluded middle, and it's a favourite refuge of lunatics all over the world, exemplified by "If you're not with us, you're against us" - a phrase used by everyone from war-mongering presidents to burgeoning Sith Lords. Time and time again, Meryl Dorey has, implicity and explicitly, claimed that vaccines just don't work.

In employing an excluded middle where in fact a continuum of grey areas exist, Meryl demonstrates a truly staggering ignorance of reality, and this black-and-white worldview marks her out as a singularly unsuitable source of reliable information in most fields, especially that of public health. Meryl's self-appointed "vaccine watchdog" status, and that claimed by her analogues in other countries, is a major problem.

Yes, there are people who cannot or should not receive vaccines. Yes, there are people for whom vaccines will do little good. A vaccinated person undergoing, say, treatment for cancer, or suffering auto-immune disease, is vulnerable to the infections they were originally vaccinated for, but this does not mean what Meryl claims it means.

Seatbelts don't always save people. Nevertheless, I always wear my seatbelt.

In fact, out here in the real world, the effectiveness rates for vaccines varies, often hovering around the 80-90% mark, as these examples demonstrate

And the trend goes on and on. These examples are neither hard to find nor hard to understand. This list took me maybe five minutes of cursory examination via Google Scholar. The medical literature is brimming with studies demonstrating the effectiveness of vaccines, but still in Meryl's world, if it's not 100%, it's nothing.

Just another reason Meryl is not qualified to comment. On anything, ever*.



*see what I did there?

posted @ Friday, May 28, 2010 11:59 AM


Comments on this entry:

# re: Meryl Dorey and the Fallacy of the Excluded Middle

Left by Bastard Sheep at 5/28/2010 12:27 PM
The odd thing is, while claiming that if vaccines are not 100% effective then it is not effective, she also claims that things like homeopathy which are 0% effective as being effective.

# re: Meryl Dorey and the Fallacy of the Excluded Middle

Left by Deb at 5/28/2010 1:49 PM
She's also demonstrating terrible understanding of herd immunity. And to be fair, it doesn't make a lot of sense - 80% means most people are vaccinated, shouldn't that make herd immunity work? Unfortunately it doesn't, numbers generally have to be much higher for unvaccinated people to be isolated, as you can see in these pictures:

# re: Meryl Dorey and the Fallacy of the Excluded Middle

Left by Jason at 5/28/2010 1:54 PM
To be honest, Deb, she doesn't think Herd Immunity is real - so any such suggestion would be immediately discounted.
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