Friday, August 16, 2013

Coincidence? What are the odds!

I bet we all have plenty of stories to tell about lucky, and unlucky, coincidences.  This post on the fifteenth of August is one of those.  When such coincidences happen, we wonder what the odds are.

Life is all about probability, as an academic acquaintance back in my Bakersfield days always liked to point out.  The odds of winning the lottery, or the odds of a plane accident, or the odds of meeting a redhead who is drawn to me.  (Zero, in the last case, as any illiterate person would even guarantee!)

The fact that we are alive, and Earth has life as we know it, is itself one heck of a demonstration of a random occurrence; as Steven Pinker put it in a different context:
We know that we live on a planet that revolves around one of a hundred billion stars in our galaxy, which is one of a hundred billion galaxies in a 13.8-billion-year-old universe, possibly one of a vast number of universes. We know that our intuitions about space, time, matter, and causation are incommensurable with the nature of reality on scales that are very large and very small. We know that the laws governing the physical world (including accidents, disease, and other misfortunes) have no goals that pertain to human well-being. There is no such thing as fate, providence, karma, spells, curses, augury, divine retribution, or answered prayers—though the discrepancy between the laws of probability and the workings of cognition may explain why people believe there are. And we know that we did not always know these things, that the beloved convictions of every time and culture may be decisively falsified, doubtless including some we hold today.
It is all one freaky set of events.  Coincidences are no different that way.  The more we interact,. the more we can expect coincidences.  As our interactions have grown geographically, and over time thanks to the long lifespans, and with the cyberspace now, well, we could certainly expect a lot more coincidences.
We are exposed to possible events all the time: some of them probable, but many of them highly improbable. Each rare event—by itself—is unlikely. But by the mere act of living, we constantly draw cards out of decks. Because something must happen when a card is drawn, so to speak, the highly improbable does appear from time to time.
It is elementary, my dear Watson!
It is the repetitiveness of the experiment that makes the improbable take place. The catch is that you can’t tell beforehand which of a very large set of improbable events will transpire. The fact that one out of many possible rare outcomes does happen should not surprise us because of the number of possibilities for extraordinary events to occur. The probabilities of these singly unlikely happenings compound statistically, so that the chance of at least one of many highly improbable events occurring becomes quite high.
Makes sense, doesn't it.

But then, remember that wonderful quote about statistics?  There are lies, damn lies, and statistics?  In this case, it is not the numbers that lie, but our own minds.  Humans that we are, we prefer to build a narrative that makes order out of the chaos that the world is.  We like convincing stories, with a beginning, a middle, and a happily ever after.
The devil is in the details of how we interpret what we see in life. And here, psychology—more so than mathematics or logic—plays a key role. ... And we also seem to be hardwired to exaggerate the chance events in our lives—because they provide us with good cocktail party stories. Psychological factors can well mask the probabilistic reality. All these factors, mathematical, interpretational, and psychological, affect how we view and understand the rare events in our personal lives.
We engage in a sleight of hand. I don't think we mean to deceive anybody--instead, I think it is our way to deal with life.

Further, because a life is lived only once, we cannot engage in any controlled experiments anyway, in order to test out any hypothesis related to coincidences.  Instead, we merely listen to charming anecdotes, and marvel at the coincidence that you and I are both alive at the same time!


Ramesh said...

You get a F grade in statistics. You have a decent chance of snagging a redhead !!!!

Sriram Khé said...

if i stop blogging and you don't hear from me, it will be because of a redhead ;)

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