The case for evidence-based medicine

Few people would openly admit that they prefer irrational treatments and doctors. But most people do in fact advocate irrational health practices – using pseudonyms for “irrational” as “holistic,” “alternative,” “homeopathic” and the deadly “natural.”

Medicine requires reason

The human body operates according to certain causal principles. If we wish to make a change in our health, we must understand some of those causal principles and act according to our understanding. To act without a rational basis is to disconnect our goals from their achievement. Irrationality does not guarantee failure — it just means that success, to the extent that it happens, will be due to other factors that our goals.

The study of human health is especially difficult

In the field of health, especially rigorous rationality is necessary for at least five reasons:

  1. The human body will solve, or at least try to solve most problems on its own. This makes establishing causality due external factors quite difficult and introduces biases such as the placebo effect and the regression fallacy.
  2. The body is very complex! Because it evolved over billions of years, the causal relationships in the body are extremely complex and interdependent.
  3. For example, even if we know that the body has too little of a certain substance, taking that substance may: a: not do anything b: cause the body to produce even less of the substance or c: cause an unpredictable side effect. On the other hand, if the body has too much of something, then the solution may be to a: consume less of that substance b: consume more of that substance or c: the consumption has no relationship at all to the level of that substance.
  4. It can be difficult to measure the extent to which medical problems are solved. While some things can be measured, many things, such as pain levels are very difficult to quantify.
  5. It is difficult to isolate causal factors in human beings since changes in health take time to develop and we can’t control every factor during an experiment or dissect human subjects when it is over.
  6. Humans tend to be irrational when it comes to their own mortality! We fear death, leading us to irrational over or under spending on health as well as being especially vulnerable to all the logical fallacies.

In medicine, rationality requires quality science research

There is a name for the field that applies rigor to the discovery of facts about nature: science. Science has been so successful in improving the state of human knowledge that many irrational, anti-scientific quacks have begun to use the term “scientific” to describe anti-scientific practices and ideas. In response to this, the medical community has come up with a term which identifiers the distinguishing aspect of rationality: “evidence based medicine.” This phrase is a necessary redundancy that identifies the essential characteristic of science: that it is based on sensory evidence. The alternative to non-evidence based science is not science at all, but emotionalism – “I feel it is true, so it must be.”

In the last hundred years, we have discovered certain practices for ensuring the conclusions of our medical experiments are valid. We know experimentally that observing these practices leads to more accurate conclusions. Let me emphasize that: the truth of medical claims is strongly correlated with the degree to which experiments follow accepted scientific standards. There are a number of objective scales for measuring the quality of an experiment.

Five characteristics of quality medical studies

Here is the essence of quality medical studies:

  1. The experiment and its results are fully described in enough detail to reproduce and compare the results
  2. There is a randomized control group
  3. The selection of control subjects is double blind
  4. The methods of randomization and blinding are accurately described and appropriate
  5. There is a description of withdrawals and dropouts.

How to judge health claims

Unfortunately, it is difficult to design good experiments and more difficult still to reach firm conclusions from most experiments. In the legitimate (“evidence-based”) medical community, the degree to which practitioners adhere to the principles varies greatly – but they at least try. Fortunately, in the “quack community,” while there is sometimes the pretense of evidence, basic scientific principles are so grossly violated and ignored that is becomes easy to distinguish fraud from legitimate science.

Here is an important point: it is difficult to make firm conclusions in medicine. But when valid scientific principles are not followed, it is easy to conclude that no valid conclusion can be reached. In other words, you can’t always be sure what’s good for you, but you can be sure when someone is talking nonsense.

Another important point: When someone makes irrational health claims, it does not mean that those claims are false. It just means those claims were not derived by rational (scientific) principles, and so we cannot say anything about their truth – we can only ignore them as arbitrary. It is as if someone claimed an invisible, undetectable pink unicorn in the sky – that which cannot be proven or disproved can only be dismissed.

How can we apply these ideas? It so happens that most health claims in the non-scientific media and many health “practitioners” are unscientific. This does not mean that they are wrong, or that people don’t feel helped by them. It means that their claims have no connection to reality.


In some cases, the practices that quacks suggest are helpful — but not for the reasons they identify. More importantly, in all cases following rational, scientific principles leads increases the likely hood of successful outcomes over quackery (aka emotionalism).

To conclude, to judge whether a medical claim is legitimate or arbitrary nonsense, check whether:

  1. It is based on quality experiments
  2. It is consistent with medical consensus (of evidence-based medicine)
  3. The certainty of the claim is well-established (by numerous studies, systematic reviews, etc




Filed under Essays

3 Responses to The case for evidence-based medicine

  1. Generally, I agree with this article’s basic premise, however, I find the increasing cronyism between big pharma and government to be disturbing. The increasing use of often-dangerous chemical use and surgical procedures in an almost knee-jerk reaction (example, patient is diagnosed with thyroid cancer–doctor, without much additional testing, orders a total thyroidectomy), when it may be quite possible that the cancer was caused by environmental and dietary means which, when corrected, may allow the body to repair itself.
    There is a large amount of money in the pharmaceutical industry and thus a strong incentive to use expensive drugs, even if low cost lifestyle changes may provide the better result. Sadly, there is no money in that for the industry, thus it is logical that, faced with a growing number of people who distrust the conventional medical industry because of it’s poor track record of healing diseases, feel that their profit potential is threatened. Hence, using the strong arm of government beaurocracy, (witness the recent paramilitary-style raids on health food coops and raw milk producers, as well as the recent anti-vitamin supplement hoax in the media) the entrenched medical establishment tries to maintain its hedgemoney. It doesn’t care about the patients’ well-being–it’s only concern is maximizing the stock holder’s share. That, to me, is immoral.

  2. David,

    You make some good points about rationality versus irrationality, but the evidence-based medicine (EBM) movement is unfortunately a mixture of good and bad. In many circles it has come to mean the practice of medicine by statistics. To the extent that statistics are used as a wholesale substitute for observing and determining what is best for a particular patient, EBM is, of course, wrong.

    Whether the growing over-reliance on statistics is a corruption of evidence-based medicine, or what the advocates of evidence-based medicine had in mind all along–to treat the collective rather than the individual–is another topic.

  3. Pingback: The Rational Mind » Warning: relying on magic and anecdotes is bad for your health

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