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Precautionary Principle

In response to my linking to David Friedman’s post on crying wolf, Cafe patron Michael writes:

I was not alive when CFC’s and acid rain were an issue. I’ve always wondered what the debate was and where scientists drew the line. Aren’t these are two examples of man made environmental impact on a grand scale? Is cutting back on potential environmental pollutants really that bad of an idea? I realize there is an economic impact, but what happens is everything is true? Isn’t investing billions now worth preventing trillions of dollars down the road? I realize this is a big “IF” , but is converting to green energy really going to hurt us in the long run? I’d rather be more self sufficient.

If I understand Michael’s sensible concern, he’s here expressing what is known in the literature as the “precautionary principle” – something like, better safe than sorry.  Stated as such, who can object?

But in fact the complexities loom large.  I haven’t time today to go further into this matter, but I recommend to Michael – and to others who are interested – Cass Sunstein’s superb 2005 book Laws of Fear.  This book explains thoroughly and with clarity that the precautionary principle in fact turns in upon itself, rendering itself self-contradictory.  Here is just one sample of Sunstein’s argument; it’s found on pages 57-58:

The Precautionary Principle cannot plausibly be defended as a form of balancing alongside risk aversion, simply because it is possible to be averse only to some risks, not to the full universe of risks.

Had I more time, I’d quote from elsewhere in his book.  (You can find my review of Laws of Fear here.)

It’s worth pointing out that Sunstein is not in the least a free-marketeer or libertarian.  He’s quite a man of the left.  Indeed, he’s currently director of OIRA for the Obama administration.  I disagree with him deeply on many issues.  But on this issue Sunstein gets matters not only right, but eloquently so.


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