The theory that repeating a myth again and again until it becomes “truth” has been formulated and systematized to a “science” by none other than Hitler’s propaganda minister Joseph Goebbels (see Goebbels’ Principles of Propaganda by Leonard W. Doob, published in Public Opinion and Propaganda; A Book of Readings edited for The Society for the Psychological Study of Social Issues). As he explained “If you tell a lie big enough and keep repeating it, people will eventually come to believe it. The lie can be maintained only for such time as the State can shield the people from the political, economic and/or military consequences of the lie. It thus becomes vitally important for the State to use all of its powers to repress dissent, for the truth is the mortal enemy of the lie, and thus by extension, the truth is the greatest enemy of the State.” This principle has been adopted wholeheartedly by certain political half-truths and outright lies – coined by one of our most astute political observers, Stephen Colbert, as “truthy”.

Actually, I am not on a political tirade here. I just want to illustrate how untruths repeated often enough can acquire a life of their own. If you think you are immune from this plague, think again. Who hasn’t heard about Darwin’s “survival of the fittest” theory? This is a shorthand used widely to describe Darwin’s principle of natural selection. The concept gained such currency that 19th and 20th-century social theorists conceived of “Social Darwinism” as a scientific basis for their theories of eugenics -the idea that the genetic stock of the human race can be improved by removing the undesirable, genetically inferior, races. The consequences of this theory reached their logical conclusion in Nazi Germany.

YET, Darwin never used “survival of the fittest” to describe natural selection. Here is what he actually said” “It is not the strongest of the species that survives, nor the most intelligent that survives. It is the one that is the most adaptable to change.” So, adaptation is the key to survival. And how did the (in)famous “survival of the fittest” come into being, inhabiting our language, consciousness, beliefs? It was a philosopher from Darwin’s time, Herbert Spencer, attempting to interpret Darwin’s theory, who coined it. But the harm was done; the catchy phrase has been repeated millions of times and became ‘”truth”.  Philosophers should be banned from teaching biology.

(In fact, Darwin viewed cooperation as a powerful adaptive strategy: “In the long history of humankind (and animal kind, too) those who learned to collaborate and improvise most effectively have prevailed.”).

Darwin was well aware of the danger of the propagation of untruths. He once said that “false facts are highly injurious to the progress of science, for they often endure long; but false views, if supported by some evidence, do little harm, for every one takes a salutary pleasure in proving their falseness.” So let me take the “salutary pleasure” in proving the falseness of one such view that has nothing to do with biology, but has everything to do with critical thinking.

Slaying the untruth

Chances are that you own some shares of Apple, either directly or through your mutual fund, index fund, 401K, or pension plan. If you do, and you don’t live under a rock, you must have noticed that the value of your Apple shares has plummeted in the last couple of weeks. In fact, the company lost $70 billion of its value, yes that’s with a “b”, in one week. Why?

A parade of gurus pontificated on TV, knowledgeable analysts wrote “research notes”, journalists published articles, all quoting the “law of large numbers”. The implication being that if something gets too big, it will eventually shrink to its “normal” size. To tell the truth, not being an economist, I accepted this “law” as gospel truth. I couldn’t see the logic, but tried to overcome this deficiency of mine by attempting to rationalize it. Never mind that every single example cited by the mavens was not applicable to the case at hand, nonetheless I didn’t hear any brave soul stand up and challenge this received wisdom. The proverbial last straw for me was an article in the New York Times by James Stewart, a Pulitzer Prize-winning financial journalist, titled “Confronting the law of Limits”. Here is a quote:

“Here is the rub: Apple is so big, it’s running up against the law of large numbers.

Also known as the golden theorem, with a proof attributed to the 17th-century Swiss mathematician Jacob Bernoulli, the law states that a variable will revert to a mean over a large sample of results. In the case of the largest companies, it suggests that high earnings growth and a rapid rise in share price will slow as those companies grow ever larger.”

Really? Companies, large or small, were the farthest thing from this 17th-century mathematician. But never mind, if he didn’t mean it, he must have. And if the statement of what the law says is not quite true, it is “truthy”.

Here is what the law of large number really means. If you flip a coin a small number of times, you may get heads say 70% of the times and tails 30%. But the more you repeat the coin flipping, the closer will the results revert to the mean, namely to 50% in the case of coin flipping. Mind you, Bernoulli is not talking about the size of the coin’s head or tail, he is talking about the sample size.

I found one brave soul, Dr. Drang (as in sturm und drang), who posted on his blog his one-word verdict: Bullshit!

“Let’s start with what the Law of Large Numbers really states. Put simply, it says that the sample mean of a random variable will tend toward the underlying population mean as the number of samples grows larger”.

Amen, brother. It is the sample mean that will tend toward the underlying population, not the variable itself. The number of heads and tails will revert to 50%, given a large enough sample size. The variable, the head or the tail, will not change in size unless you shrink the coin.

How could that happen?

Simple; the emperors have no clothes. They are intellectually lazy, parroting each other without bothering to check the facts.

Circling back to where we started, Charles Darwin. He said: “To kill an error is as good a service as, and sometimes even better than, the establishing of a new truth or fact”.

Happy to oblige, uncle Charles.

Dov Michaeli, MD, PhD
Dov Michaeli, MD, PhD loves to write about the brain and human behavior as well as translate complicated basic science concepts into entertainment for the rest of us. He was a professor at the University of California San Francisco before leaving to enter the world of biotech. He served as the Chief Medical Officer of biotech companies, including Aphton Corporation. He also founded and served as the CEO of Madah Medica, an early stage biotech company developing products to improve post-surgical pain control. He is now retired and enjoys working out, following the stock market, travelling the world, and, of course, writing for TDWI.

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