Tuesday, January 11, 2011

Chance and inevitability

In an op-ed in today's issue of the Los Angeles Times, Michael Shermer wrote about the rush "to find the deep underlying causes of shocking events", with reference to the shooting in Tucson, Arizona and the recent mass bird deaths.

Shermer made some good points, but parts of his argument were flawed. For example, he cited statistics from the National Institute of Mental Health to argue that unbalanced people are not uncommon, and
Given these statistics, events such as the shooting in Tucson are bound to happen, no matter how nicely politicians talk to one another on the campaign trail or in Congress, no matter how extreme tea party slogans are about killing government programs, and no matter how stiff or loose gun control laws are in this or that state. By chance — and nothing more — there will always be people who do the unthinkable.
In other words, he is pointing out what he sees as an inevitability, and then attributing it to chance. But an inevitability is the opposite of chance: it is a systematic pattern. And a systematic pattern is precisely what we can hope to change. I tend to agree with Shermer that "there will always be people who do the unthinkable." But surely we ought to do what we can to make such occurrences as rare as possible, and to reduce the harms as much as we can.

Shermer finishes his piece as follows:
... as often as not, events in life turn on chance, randomness and statistical probabilities that are largely beyond our control. So calls for "an end to all overt and implied appeals to violence in American politics" — such as that just issued by MoveOn.org — may make us feel better, but they will do nothing to alter the inevitability of such one-off events in the future.
By definition "one-off events" are unpredictable and idiosyncratic. And yet Shermer says they are inevitable. The apparent confusion here is between statistical probabilities that can be used to make fairly certain predictions, and the virtual impossibility of prediction at the micro level. For example, age- and sex-specific incidence rates of different types of cancer are carefully tabulated by the CDC, and we can use these rates to predict the number of people who will be diagnosed with cancer this year. But we can't predict well who those people will be. There are, however, patterns. We learned that smoking causes lung cancer (and heart disease, and emphysema, ....) and through reduced smoking rates we have seen reductions in mortality [pdf]. Perhaps we do have some control after all.

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2 Comments:

Blogger Ellie K said...

Please write more posts! I found my way here via the Pyjamas in Bananas blog. Your articles are very good. Yet you have been silent since January! Such a congenial blog name as well.

I will keep my fingers crossed, that more pithy, math-y, yet accessible articles will be forthcoming in the near future.

P.S. I like the lizardy creature on the lower right. He is like a lagniappe. Very engaging!

8:13 AM, May 28, 2011  
Blogger Nick Barrowman said...

Thanks, Ellie. That's just the encouragement I need!

(Glad you like the lizardy creature. I'm a big fan of lizards, and the way they randomly pop up!)

10:34 AM, May 28, 2011  

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