Nov 03 2015

David Katz Tilts at Straw Men

How one responds to legitimate criticism is a very good indication of their intellectual fortitude and integrity. I pay specific attention to whether or not they address the actual criticism, rather than attack a convenient straw man, and whether or not they acknowledge fair points on the other side. Intellectual discourse, which often contains pointed criticism, is critically important. It is how we work out big ideas and move forward.

In a recent blog post on the HuffPo, David Katz launches into a fallacy-ridden attack on Science-Based Medicine, managing to entirely mischaracterize our position, despite the fact that our position has been exhaustively discussed on our blog and elsewhere. His post,¬†Science and Medicine, Fools and Fanatics: The ‘Fluidity’ of Woo, contains the usual alternative medicine tropes draped in protests of his academic credentials. David Gorski has already responded over at SBM, and I would like to add to his analysis here.

David Katz first defends his infamous statement advocating that medicine should use a “more fluid concept of evidence.” He writes:

Colleagues and I proposed, based on years of wrestling with complex patients, many of whom, urgent medical needs still insufficiently addressed, had tried and exhausted all of the well-supported, conventional treatments, that evidence traversed 5 key considerations. Those include: what is known about a treatment’s safety; what is known about a treatment’s efficacy; how well those first two are known (i.e., the clarity of evidence); the patient’s preferences; and, importantly, the availability of other, untried treatments for the condition in question.

He argues that when science-based alternatives are exhausted, a caring clinician should consider treatments with a more “fluid” standard of evidence. Since he apparently did not understand our original criticism, I will spell it out carefully here.

First, the suggestion that we “abandon” patients when rock-solid treatments are not available is a straw man (not to mention insulting). He is desperately trying to equate adhering to high standards of science with not caring about patients. The opposite, of course, is true. We advocate for high standards precisely because we want what is best for all patients.

In fact, the 5 considerations he outlines above are all reasonable, as far as they go. I agree and have agreed in the past with taking a tiered approach to treatment – start with the best, most evidence-based treatment and then work your way down. Where David and I disagree (and we have had this discussion face-to-face) is on two critical points: plausibility, and evidence for lack of efficacy.

The hallmark of science-based medicine is that we think evidence needs to be looked at in the context of overall scientific plausibility, otherwise you are ignoring an important chunk of the scientific evidence. David explicitly rejects plausibility as a consideration. He does so again in this article, writing:

The guardians will be there all along, telling us what is possible, and what isn’t — until it turns out it is. At which point, they will revise their fluid definition of woo, and pretend it never happened.

He uses the tired, “Science doesn’t know everything,” argument (complete with the Galileo gambit), and equates anyone who makes a plausibility argument with a fool or fanatic. In practice, his position is equivalent to, “We don’t know everything, so let’s behave as if we know nothing.” This position, however, is absurd,

While decrying proponents of SBM for committing a false dichotomy, as if evidence either exists or does not exist (which is a straw man, since we don’t do that), he himself commits a false dichotomy logical fallacy here. He is essentially arguing that unless we can be 100% certain of a scientific claim, we can safely ignore it.

However, SBM does not hold that we currently know anything scientific with 100% certainty. Scientific knowledge is all about probability. When we give a treatment to a patient we want to have the best assessment possible of the probability of risk vs the probability of benefit. Our point is that in order to know the probability of both you need to properly consider direct evidence in the context of scientific plausibility.

Plausibility is similar to prior probability. If a treatment, like homeopathy, which David Katz advocates, violates multiple fairly solid scientific principles, then the probability of the treatment working is low. It seems like a trivially true statement that scientifically plausible claims are more likely to be true than scientifically implausible claims, almost by definition (unless you think that our current scientific knowledge is literally worthless).

The second point on which we disagree regarding the tiered approach to medicine is how far down the list of possible treatments a practitioner is willing to go. I think there is a line below which you are no longer practicing medicine but something closer to witchcraft. Yes it’s a fuzzy line, but it’s there. I would put below the line treatments with extreme implausibility and treatments for which there is evidence of lack of efficacy.

When I suggested this to David on one occasion he literally responded, “how can you have evidence that something doesn’t work?”

This is generally how proponents of alternative medicine behave – claims for any treatment are ratcheted up with any positive evidence, and negative evidence is ignored (as is plausibility).

Another aspect of SBM that David ignores are the many studies that show how challenging it is to do reliable clinical research. There is a massive false positive bias in the literature, for example. Most preliminary studies turn out to be wrong, in the positive direction.

It is unequivocally true that if you use David’s “more fluid concept of evidence” and ignore plausibility you will be giving patients many treatments that do not work, all the while defending it as compassionate. I don’t think giving a patient an ineffective treatment is compassionate. It is a waste of time and resources, is not without risk, gives false hope, violates patient autonomy, and instills counterproductive unscientific beliefs that may hamper proper medical treatment in the future.

It is difficult to appreciate the implications of our different approaches to evidence and science in medicine completely in the abstract. How our different approaches manifest puts them into better relief. David gives two examples in his article, his acceptance of homeopathy and energy medicine.

Homeopathy is not just implausible, it is the poster child for incredible implausibility. For homeopathy to work, water must retain the memory of complex molecules that had been diluted in it, and that memory must survive processing, storage, ingestion, digestion, absorption into the blood, and then somehow have a biological effect. Every step in this chain is massively implausible.

Further, there must be some mystical connection between the original substance and the process that is causing the symptoms the treatment aims to relieve. Homeopaths base their choice of original substance on fanciful notions that resemble witchcraft.

To see the truly bizarre depths that this logic leads, some homeopaths offer a homeopathic dilution of a small piece of the Berlin Wall in order to treat things like a feeling of isolation or oppression. This may seem transparently absurd, but it follows the same logic as all other homeopathic remedies.

You have to ask yourself, what is the probability that the universe actually works this way, and that one German physician figured this all out 200 years ago? Further, what is the chance that the universe works this way, but that 200 years of subsequent science has failed to find anything in the workings of nature that support these notions or could provide a plausible mechanism? Philosophically I have to acknowledge it’s not zero, but I think it is absurd to treat it as anything other than zero from a practical point of view. David Katz apparently thinks that position is fanatical and foolish.

David also makes an elaborate argument for the existence of an unseen bio-energy field, something which is used as a hand-waving explanation for many implausible treatments. He argues that because some animals can see frequencies of light we cannot see, or hear frequencies of sound we cannot hear, that perhaps there are energy fields that most people (except a special few) cannot detect.

Of course he is missing the big flaw in this analogy – we can use instruments to measure frequencies of light and sound humans cannot biologically detect. We have a coherent theory of how light and sound work that is supported by a mountain of evidence.

His bio-energy field is not detectable by any scientific instrument, is not part of any model of physics, and further is completely unnecessary to explain the biological functions of life. A life force was nothing but a placeholder before we figured out how biology works. Over time it faded into uselessness – there was nothing left for the life force to do.

Physicists would also have a hard time explaining the existence of another type of energy entirely, one that has not been observed at work in the universe. I can’t say it’s impossible, and it’s hard to prove a negative, but the arguments against the existence of a bio-energy field are massive and cannot be blithely ignored.

At the same time, proponents of energy medicine have no solid or even mildly compelling clinical evidence to suggest that such an energy field can be exploited for any clinical outcome.

There is a pattern here, one that I am very familiar with as a skeptic – highly implausible claims tend to be supported by incredibly weak evidence. I don’t think it’s a coincidence. Proponents then use special pleading to rescue their failing claims: science doesn’t know everything, I’m still right because Galileo, my critics are arrogant, there’s a conspiracy against my new and fabulous ideas, science cannot penetrate my subtle and profound energies, but ancient wisdom, etc.


David Katz does not make any new arguments in his screed, and manages to completely miss the point of our prior criticism. He ends in the same vein:

Bertrand Russell¬†famously said: “The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts.” How ironic that those ranks are now expanded by self-proclaimed sentinels of science, devoted instead to dogma, demagoguery, and the certainty that if it matters, they know it already.

It is amazing that he has this entirely backwards. It is the skeptics who are advocating for doubt. One major point of SBM is that we need more doubt. Our methods are still a bit crude, and we need to refine them, to question everything a bit more carefully, and to root out bias and error.

It is the gurus who defend magic as medicine who are so certain of themselves that they will stick to their claims despite an utter lack of plausibility and credible clinical evidence.

SBM is a philosophy of humility. Alternative medicine or whatever proponents want to call it is the ultimate hubris. It is the elevation of their personal wisdom above science, evidence, and even logic.

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