The Improbability Principle

Book Review : The Improbability Principle

Author : David Hand

My Rating : 5 out of 5 stars

The complete title of the book is “The Improbability Principle: Why Coincidences, Miracles, and Rare Events Happen Every Day”.

Who hasn’t experienced minor coincidences? Of course, everyone has. Even when it comes to rare events, most of us would say that we have experienced at least one such event. Are these just purely random occurrences? Many believe that they are not, and in their view, some divine power is at work. Some believe in miracles. Perhaps many more believe in supernatural abilities of certain individuals - whether it’s telepathy or seeing future or something similar. Can there be a rational explanation for all this, without invoking any argument about some divinity?

In this book published by Scientific American, the renowned statistician David Hand has provided a lucid explanation based on probability theory. He has given the theme a very catchy name, “The Improbability Principle”. With it, he asserts the paradoxical statement, “Rare events happen every day”. Wait a minute. If it’s rare, then it cannot happen every day, right?

Well, what’s rare from one individual’s point of view, is not really all that rare in a very large sample size. That’s the crux of the matter. There are other interesting aspects, and the author introduces much more rigor in his argument. The improbability principle, as per his definition, has many strands. He names them, “the law of inevitability”, “the law of truly large numbers”, “the law of selection”, “the law of the probability lever” and “the law of near enough”. Many readers would be intuitively familiar with the first two strands. I was. The formalization of other three strands was very interesting to me. Especially, “the law of near enough” which says that events that are sufficiently similar may be regarded as identical, and that can give rise to many apparent coincidences. 

All these strands are neatly arranged into individual chapters and explained using real life situations. This makes the book an easy read. There is as little mathematics as possible, and the author tries hard to make sure even those who are not mathematically inclined understand the argument well. The downside of this is, some material feels repetitive. 

The examples range a wide spectrum of topics, from gambling, accidents, psychics, science,  evolution and religion. The last two topics were most interesting to me and I wish those chapters were more extensive. In his argument, which I completely agree with, human intuition evolved to help us survive, and for that very reason it understands certainty better than uncertainty. That makes us want to believe in religion, and divine intervention.

That also raises an interesting question in my mind. Will anyone ever change their opinion by reading such books? I guess not. I was already in agreement with most of what the author is arguing, so it’s very easy for me to appreciate the strength of his arguments. If someone is already convinced that miracles do happen, I doubt this book will reverse that opinion. Because the desire to believe is so strong, that no rational argument has any chance to work.

That aside, I highly recommend this fantastic book. It’s extremely easy to read and all readers will find it insightful, regardless of their inclinations.