23 August 2008

The Monty Hall puzzle

Suppose you're on the old quiz show, "Let's Make a Deal." For those of you who are too young to remember it -- don't worry, you'll catch on as we go along. Quiz shows are quiz shows through every generation.

The host, Monty Hall, shows you three curtains: A, B, and C. Behind one of these curtains is a fabulous prize. Behind each of the other two is some absurd gag gift.

At random you say, "I'll take what's behind curtain A, Monty."

Monty replies, "Before we pull back A, let's pull back C, just for fun."

His beautiful assistant gracefully pulls back curtain C revealing ... a mound of shaving cream.

Then Monty turns back to you and asks: "Do you want to stay with A, or change your guess?"

Well ... do you? Does it matter one way or the other for your chances whether you do?

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Knowledge is warranted belief -- it is the body of belief that we build up because, while living in this world, we've developed good reasons for believing it. What we know, then, is what works -- and it is, necessarily, what has worked for us, each of us individually, as a first approximation. For my other blog, on the struggles for control in the corporate suites, see www.proxypartisans.blogspot.com.