poly: Buying groceries

From: Nick Bostrom <bostrom@ndirect.co.uk>
Date: Mon Nov 09 1998 - 15:40:32 PST

Buying my groceries today during rush hours, I had to wait some
five minutes in a queue in order to pay. During this time I
thought of the following simple way of cutting the queues: Instead
of having every customer pay for his groceries, let everybody
activate a randomizing machine when they are about to exit. With 50%
chance a green light flashes, and with 50% chance a red light
flashes. If green light, then you just pass without paying; if
red light then you pay twice the amount you'd normally do.

Isn't this simple enough that it might work, if only you could
get past people's inertia and their attitude problems against
gambling etc.?

I told the idea to my girlfriend, and she thought that it would be
"unfair", presumably referring to the risk aversion that customers
might have (which seems rather irrational on customers' behalf, given
the small sums involved).

It would be possible to remedy this but on pain of introducing
complications. You could have each customer choosing how much they
want to pay. Then they pass the random device and if green they just
pay what they agreed to; if red they pay (or get) twice the
difference between what they agreed to and the price of their
merchandise. By making a rough estimate of how much you are buying
for, you could thus reduce the risk.

I prefer the original version because if its simplicity.

Nick Bostrom
http://www.hedweb.com/nickb n.bostrom@lse.ac.uk
Department of Philosophy, Logic and Scientific Method
London School of Economics
Received on Mon Nov 9 23:44:31 1998

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