Patterns You Find In History, Social Science, and Nature


I was having an interesting online conversation with someone who was telling me about a number of historical coincidences that I might not be aware of.  I wanted to use an example from a noted physicist, but, in a senior moment, I could not remember his name.  I remembered enough of the story to convey the idea, though not as well as the original story did.

A little later the name popped into my mind, and I was able to find this reference online.  I want to record it here for my future reference.

There is a blog article Richard Feynman, Erik the Red, Earl Henry Sinclair, and Cristopher Columbus:

The mind sees what it wants to. It is an excellent detector for patterns in seemingly random data, but it also excels at making patterns where none exist. It’s built to do that. It’s how we learn. And that often gets us into trouble.

Dick Feynman had a very interesting teaching trick to illustrate this problem – he used it several times in different situations, ranging from his freshman physics lectures at Caltech to his lectures during trips after his Nobel Prize award. Feynman would suddenly interrupt himself in the middle of a statistics lecture, and excitedly say something like: “On my way to campus today, I saw a car with the licence plate XRT-375 in the parking lot – isn’t that amazing? What are the odds of seeing that exact licence?” After letting the class wrestle with exactly what he was asking, he would make the point that there is a HUGE difference between calculating odds before the fact and after the fact. The chance of seeing that particular plate is simple to calculate: 1/26*1/26*1/26*1/10*1/10*1/10, or about one in eighteen million. And it really would be amazing if you picked a number out of the air, and then found it in the lot. However, Feyman’s point was that having seen the plate first, it is unremarkable that you then ask the question about that particular number. The chance is unity. You can’t use a set of data to make a hypothesis, and then turn around and use that same data to test the hypothesis!

I hope the lesson learned is that you cannot poke through history, discover a number of items that are similar, and then say, “That’s an amazing coincidence.  What are the chances that all these things in this list would happen?”  If you search for random things and create a list of things that did happen, then the chances are 1 out of 1  that they did happen.

Here is a great example of the problem,  Lincoln–Kennedy coincidences urban legend.

The coincidences between Abraham Lincoln and John F. Kennedy are a piece of American folklore of unknown origin.

You see the same logical fallacy in stock market systems and roulette wheel systems.  You might also want to look at one of the most popular posts on this (my) blog,  Diversion–Highway Fatalities and Lemons, by RichardH.


Of course, if I cannot remember the name of the physicist, it won’t help me to record this story here. See Feynman in the blog post Bad Science: Quacks, Hacks, and Big Pharma Flacks. The funny thing is that I thought I did search for “quack”, but I did not find anything. (Accidentally had “match case” checked.)

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