Science-Based Medicine 101: Plausibility

In part 2 of the Science-Based Medicine 101 series we take a look at the second pillar of good science: plausibility. This blog post was written for a lay audience so more advanced readers will need to indulge me here…


I really enjoy sci-fi action movies. I love the convincing special effects and the fact that heroes can accomplish the physically impossible without skipping a beat. Implausible events unfurl with convincing reality, and you never know what might happen with the plot.

I also enjoy the TV show, America’s Funniest Home Videos, for different reasons. The mundane nature of actual reality, and the often predictable, but hilarious mistakes made by those I relate to result in some pretty hearty laughs.

But there is a big difference between these two forms of entertainment: science-fiction requires the suspension of belief in plausibility, while home videos are based on plausible outcomes. When it comes to medical research, though, plausibility can mean the difference between science fiction and reality.

Over the centuries, scientists have eagerly concocted explanations for medical phenomena. However, it wasn’t until quite recently that our knowledge of science has expanded into an amazingly concrete and fairly deep factual account of how things work. I credit the scientific method for these astonishing advances that have vastly improved our quality of life. Without rigorous testing, repeating, and retesting in a controlled manner, we wouldn’t have many of the life-saving medicines, procedures, devices, and treatment options that we have today.

And yet, we really like science fiction. We like to believe in magical solutions and discoveries that break the mold – that there could be something out there that we find that no one else has thought of yet, or observed, or harnessed. This drive to discover is a wonderful force for investigation and scientific advancement, but it is a double edged sword. The other side can result in irrational beliefs, magical thinking, and snake oil science.

Take for example the field of homeopathy. Founded by German physician, Samuel Hahnemann in the 18th century, this system of medical treatment is founded upon the principle that like treats like, and that a medicine is at its strongest when it’s at its weakest possible concentration. So, for example, if you have cold symptoms (runny eyes and nose) the treatment would be to drink onion juice (because onion fumes produce runny eyes and a runny nose), but at a concentration so dilute that there is actually not even one molecule of onion extract left. Hahnemann believed that water has memory – and that the fact that water molecules had been recently in the presence of onion molecules gave the water healing powers. In fact, the act of shaking the water made it even more potent as a therapy.

Now, I have no doubt in the sincerity of Hahnemann’s beliefs. I also have no doubt that homeopathy (for those who believe in it) can have a strong placebo effect. But to believe that there is an actual physiological effect of shaken water for the treatment of all sorts of diseases, is to deny everything that is known about human physiology, immunology, genetics, and biochemistry. Should one man’s beliefs negate the results of millions of scientific studies? The proposed mechanism of action of homeopathy is implausible, and therefore may be confidently discarded as anything more than a placebo. (And if you don’t believe me, Dr. Barker Bausell has a wonderful review of the homeopathy literature that confirms this).

Well, some of you plausibility skeptics say, Galileo’s beliefs (that the earth is round, not flat) were not accepted by scientists in his day (and yet he was right and they were wrong), so how can we say with certainty that any proposed mechanism of treatment is truly implausible? Isn’t anything possible?

I suppose a tornado could tear through a junk yard, creating a Boeing 747 by accident, though I’m pretty sure we’ll never see that on America’s Funniest Home Videos – though we may see it in a sci-fi movie. But I’m glad you asked about anything being possible – because this brings us to our final pillar of good science: reproducibility. If something is true, it should be true again and again, right? Galileo was proven right because in test after test, ships did not fall off the end of the “flat” earth. Its in the repetition of tests that we can confirm the truth. Next week we’ll take a final look at evidence through the lens of reproducibility.

Posted in: Homeopathy

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