Once again: “Plausibility” does not mean “knowing the mechanism”

I tend to get lost in complexity from time to time.

I know, big surprise to my regular readers, but I suppose it’s a good thing that at least I know that this is a weakness of mine. Indeed, it must be part and parcel of my seeming tendency to produce epic posts of ridiculous length that sometimes surpass 5,000 words, although, in all fairness, my average post length is probably less than 2,000 words, which is still too long for many people but not beyond the pale. Of course, part of the reason for this is that I like to leave no stone unturned. In particular, I tend to like to make my refutations of the various bits of pseudoscience, quackery, and antivaccine nonsense that serve as the fodder for Orac-ian Insolence, Respectful and otherwise, as comprehensive as possible. I imagine the various targets topics of this blog, stung by having their bad science, logical fallacies, and bad reasoning punctured, looking for a single weakness that they can attack, believing that doing so will cause my entire argument in a post to come tumbling down. That’s why I try to construct many of my posts like the proverbial spider web, with intermeshing arguments weaving together into what (I hope) is a seamless whole, where, even if I made a mistake in one area, the rest of the web remains sound. My computer ‘nym notwithstanding, I am actually human and do occasionally make mistakes from time to time that go beyond typos or the occasional fragment or run-on sentence.

So it’s a rare treat when I find a bit of nonsense that is not only allows me to explain a nice, simple principle that quacks frequently try to misrepresent for their benefit but actually foreshadows a post I was planning to do in the near future, I can’t resist. It’s therapeutic. Maybe I can even keep this post under 1,500 words (although I’m sure some smart-ass will note that I’ve already used up over 300.) That nonsense is, not surprisingly, a defense of homeopathy. It is, however, a defense based on a single statement and entitled If Homeopathy Can’t Work, Then Neither Can Anesthesia. Not surprisingly, it’s written by Heidi Stevenson, a homeopath whom we’ve met before pontificating about how anecdotal evidence is better than clinical trials and making nonsensical attacks on Stephen Barrett, but her screed is so brain dead that it could well have been written by Dana Ullman. Let’s take a look, shall we.

The first paragraph pretty much sums up the fallacy upon which Stevenson constructs her nonsensical argument. It’s basically the argument against prior plausibility. Regular readers migh twonder why I (and other skeptics) write about homeopathy so much given how utterly ridiculous and easily refuted it is from a scientific standpoint. The reason that homeopathy is so useful for discussing the science of clinical trials is that it is, basically, water. As has been explained so many times before, the original remedies are often diluted to the point where it is incredibly unlikely that even a single molecule remains. That makes it a perfect vehicle to discuss the issue of plausibility (because homeopathy has none) and prior probability that homeopathy will work in a clinical trial (which is about as close to zero as it is possible to get an not actually be zero).

I’ll talk a bit more about the prior probability issue in a future post. For purposes of this post, I’m more interested in plausibility. What really bothers homeopathy supporters is the argument that homeopathy is incredibly unlikely to be doing anything beyond placebo because it’s so incredibly implausible on basic science considerations alone given that its tenets…oh, you know…break multiple laws of physics and chemistry. Quacks, particularly homeopaths, like to turn this objection into a straw man, and Stevenson does just that:

One of the most common arguments against homeopathy says: It can’t work, therefore it doesn’t. Another throws out the challenge to explain how it works. Neither is a fair argument, since they do not care about evidence showing its efficacy, but only attempt to demean both homeopathy and the person who believes it works.

No, Heidi. The argument is not “It can’t work; therefore it doesn’t.” The argument is that it is so incredibly implausible on basic science considerations that homeopathy is in essence an extraordinary claim. To convince scientists and skeptics that an extraordinary claim is true (or at least plausible) requires extraordinary evidence. The way I like to put it is that the amount of evidence that it would take to make homeopathy scientifically plausible should at least be in the same order of magnitude as the quality and quantity of evidence amassed over centuries of physics, chemistry, and biology that currently leads to the conclusion that homeopathy is scientifically impossible. Equivocal clinical trials with barely statistically significant findings of low magnitude do not constitute evidence sufficient to conclude that physics, as we understand it now, is in doubt.

More amusing is Stevenson’s example:

These same people do not place the same burden on their own belief in allopathy. Let’s pose that question to an anesthesiologist, Michael Alkire of the University of California School of Medicine, who is recognized as an expert in his field. Surely he knows the answer. His response is in a quote from the Encyclopedia of Consciousness:

How anesthesia works has been a mystery since the discovery of anesthesia itself.

Do those who keep attacking homeopathy care that no one understands how anesthesia works, either? Oddly enough, that never seems to come up. Why do they hold homeopathy to a different standard? Not knowing the mechanism behind how something works is hardly a legitimate argument that it doesn’t.

No, no, no, no no, no, no!

Repeat after me: Implausibility (as applied to considering the claims of homeopathy) does not equal “not knowing the precise mechanism.” We base our conclusion of the extreme implausibility of homeopathy not on our lack of knowledge of its mechanism (although there’s no doubt that in general plausibility is bolstered by knowing the mechanism by which a treatment works). It is based on the reasonable scientific assessment that any mechanism that anyone can possibly think up by which homeopathy might possibly work violates very well established laws of physics and chemistry. In other words, as I’m so fond of saying, perhaps to the point of repeating it too often, for homeopathy to be true, huge swaths of physics and chemistry would have to be not just wrong, but spectacularly wrong.

It would take a hell of a lot of evidence to start to make me (or any other scientists) begin to think that.

I would also point out that, yes, there is a lot about anesthesia that we don’t understand. There is a lot about the brain that we don’t understand. We do, however, know beyond a shadow of a doubt that anesthesia does in fact, work. In fact, the very article Stevenson linked to is anecdotal evidence of that! Carl Zimmer, who wrote the article, describes his surgery for appendicitis and how it was odd how it seemed as though the couple of hours he was out was as though the anesthesiologists had “cut a few hours out of my life and joined together the loose ends.” We know that anesthesia works, under what conditions it works, how much and what kind of drugs it takes to achieve certain affects, and the dose-response curves and pharmacology of the agents used. Some agents have mechanisms of action that we understand quite well (opiods), some not so well (inhalational agents). But we know they work. We know that they must work through chemical interactions between the agent and cellular proteins that can be studied and characterized. We know that, unlike homeopathy, even though we don’t know all the mechanisms by which some anesthetics work, their working does not require the violation of even a single law of physics. The same cannot be said of homeopathy.

It’s also a bit of a bait-and-switch on Stevenson’s part. Zimmer’s article wasn’t so much about how we don’t know how anesthesia works, but rather musings on how little we know about consciousness, how unconsciousness is achieved through anesthesia, and how the brain maintains consciousness. We do, however, know that there are many changes in brain activity during anesthesia. These can be measured and characterized, allowing scientists to infer potential mechanisms and then test them. In other words, Stevenson zeroed in on the one sentence in Zimmer’s article and ignored the rest.

The next passage from Stevenson’s article couldn’t help but make me think of Insane Clown Posse:

Do we understand how electricity works? Outside of observations of its effects, we do not. It is a subatomic phenomenon, and that field is in extreme flux right. In a world in which things do not exist unless they are observed, as postulated by modern physics–and not having the slightest idea how this can possibly be–we cannot possibly claim to know how electricity works. So, is it legitimate to suggest that electricity cannot work because it consists of particles that, quite impossibly, exist only when they’re observed?

The real world is a very complex and mysterious place. Though we certainly must make determinations of what is and is not real, isn’t it best to do that based on experience and observation, rather than presumptions of what can and cannot be?

Did the sun suddenly come into being the day we humans were finally able to theorize a means by which it shines?

Must we give up anesthesia because we have no idea how it works?

How can rational people make the claim that homeopathy doesn’t work simply because we don’t know how?

F*ckin’ magnets, how do they work?” Really, how do they work? And this is how magnetism and electricity work, Heidi. You are clearly an ignoramus. Maybe you should talk to real scientists. I suppose if I told Heidi that electricity and magnetism are related it would crack her fragile eggshell mind. The hilarious thing is that several commenters (assuming they aren’t deleted by the time this post goes live) are taking Stevenson to task for her extreme ignorance, pointing out that we’ve understood pretty well how electricity works for a hundred years. My favorite is the one who pointed out that the result of our understanding how electricity works is the very computer upon which Stevenson wrote her article and the web servers that serve up her bloggy nonsense to the world, not to mention my computer upon which I unfortunately came across her bloggy nonsense. That doesn’t even count how the microprocessors in computers relies on an understanding of quantum physics to work.

Stevenson’s whole argument is basically one huge argument from ignorance. In essence, she is saying, “If we don’t completely understand how, for instance, anesthesia works, then that means total pseudoscientific quackery like homeopathy could work.” Yes, her argument is just that awful.

But, then, what do you expect from a homeopath?