ELECTION outcomes are chaotic, say mathematicians who study group
decision-making.
Computer modellers have already predicted that electronic stock trading could
cause chaotic market swings if large numbers of computer programs are allowed to
鈥渧ote鈥� for which stocks to buy
(This Week, 4 July, p 7).
Now David Meyer, a physicist at the University of California at San Diego,
and Thad Brown, a political scientist at the University of Missouri, say the
same thing happens in all group decisions. 鈥淎lmost any voting rule gives you
chaotic outcomes,鈥� he says.
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Their mathematical proof, which will appear in a future issue of Physical
Review Letters, shows that even if the preferences of a group of voters
change only very slightly, the results will be completely unpredictable a few
elections down the line. Such sensitivity to initial conditions is a defining
feature of chaos.
鈥淟ook at Italy, with some fifty governments in the past few decades,鈥� says
Meyer. 鈥淚t鈥檚 a serious phenomenon.鈥�
