Monday, May 11, 2009

How Juries Decide

There's a great article in the May 9th issue of Science News concerning how, in the absence of gigantic brains, swarming honeybees decide where to establish a new colony. No brains might seem like a handicap, but bees, with just enough brainpower per individual to light up their own billionth of an amp of awareness, manage to make some remarkably astute decisions when acting in concert.

The rules seem to be:
  1. A few hundred experienced bees leave their naked and unprotected swarm and scout the countryside for likely real estate to colonize.

  2. Maybe only 20 or so scouts find suitable candidate sites.

  3. These scouts return to their swarm, recruit supporters for the new location and direct them to the new site by waggle-dancing.

  4. The new supporters check out the site and become converts (or not), waggle-dancing in competition with all the other scouts and their converts. Satisfied, the original scouts stop dancing.

  5. The candidate colony site which is still buzzing when all the lesser colonies have lost their advocates by natural attrition is the winner; the winning consensus is reached, and the colony moves to its chosen location.
The curious thing is, the site chosen is nearly always optimum — well-suited for a real world where evolution and natural selection take a mordant bite out of bad decisions.

This astonishment naturally begs for comparison with the English common law jury system, which has no evident author either, but which seems to function well in most cases. "Twelve good men, tried and true, is a good system," one of Agatha Christie's protagonists remarks (Colonel Arbuthnot with the Truism in Murder on the Orient Express) Is it an accident that juries have twelve members? Who decided that? The number twelve has a remarkable property; it can be divided by 6, 4, 3, 2 or 1, rather like the number of groups that gradually coalesce into unanimity. Other numbers may contain both odd and even groups, like either three groups of 4 or four groups of 3, but twelve seems neatly packaged.

Does the judge issue instructions to the jury to teach them the law? Or to ensure that the jury sees every possible outcome? If jurors restrict their options prematurely to "obvious" choices, thumbs up or thumbs down, hands down it is not just the outcome but the justice of the decision that is in doubt. If you have four or five opinions distributed usually (but not invariably) according to severity of the offense then more positions find advocates, more discussion occurs, more time elapses and more hotheads quench themselves in the cool deliberations of the main jury pool.

The one jury I was ever on proceded exactly along this course. My opinion at the beginning was exactly the same as the decision that was reached, but I wore myself out arguing against the not inconsiderable number who favored immediate acquital. Everyone got tired of arguing, and in the end, as if by magic, in the heat of the afternoon, through the blinding migraines, an "obvious" consensus was reached (guilty of a lesser charge). That happened to be my opinion, but I hardly owned that moment. The entire jury wrote that verdict, memorable only for its utter triviality (as I recall, a bouncer may have used too much force ejecting an unruly patron from a bar). It seemed important at the time.

A system so mindless, so chaotic, so correct can only have evolved. No one could imagine it.

One wonders if rules similar to those used by swarming honeybees governed the Pilgrims' journey to Plymouth Rock, or the Amish to Kalona, the Mennonites to northwest Missouri, or Christian Metz's 19th century German Inspirationists to the seven villages of Amana near Iowa City?

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