Chances Are (35 page)

 

Of all the deified virtues of the ancient world—Wisdom, Domesticity, Revenge—we set up statues only to Justice. She alone remains a goddess, perhaps because justice is so hard to define as a human quality. It should be eternal yet contemporary; absolute in law, yet relative to the case. We understand that legal proof—whether by the preponderance of evidence or beyond a reasonable doubt—is a matter of probability; but that the choice, once made, goes by forever 'twixt the darkness and the light.

Trial by jury represents our attempt to wring error out of judgment. We hope that, as with scientific observation, averaging the views of twelve citizens will produce a more accurate result than asking just one. This assumes, though, a normal distibution of juror prejudice around some ideal, shared opinion—but prosecutors and defenders alike try to skew that distribution through juror selection.

Different lawyers swear by different systems: one considers the Irish likely to feel sorry for the accused, another thinks they have too many relatives in law enforcement. The great defender Clarence Darrow sought out Congregationalists and Jews, but strove to purge his juries of Presbyterians. Everyone agrees that suburban homeowners convict: they fear crime, worship property, and haven't suffered enough. It is an axiom that if your client is likely to be found guilty, you must try to get a cantankerous old woman on the jury, who will enjoy resisting the eleven others.

Modern methods of jury packing began, surprisingly, with the trials of antiwar activists in the 1970s, when volunteers from social sciences departments profiled the various shades of opinion in the towns where cases were coming to trial, giving their advocates the ability to shape the jury through summary objection. Their success inspired a whole industry: one of the professors, Donald Vinson, opened a $25 million firm to offer the benefits of social profiling to the wider world. He claimed that if you ordered his full range of services you could be 96 percent sure of the verdict—which is the kind of justice worth buying.

 

Law is what lies beneath, but it also means
fairness
—“giving someone his law” used to be the term for a head start or a favorable handicap. The biggest legal fiction of all is the pretense that the process itself assures fairness, when it is we who should do so. It is we who take the continuum of experience and assign it to one of two doors (except in Scotland, where the third door is “not proven”—colloquially, “not guilty, but don't do it again”).

What, therefore, do we need to assure that justice is “what usually happens”? British law has long relied on the idea of the “reasonable person,” defined, at the turn of the twentieth century, as “the man on the Clapham omnibus.” The image was carefully chosen: Clapham, south of the Thames, was a bulwark of lower-middle-class respectability. The man on the omnibus would be jolting home from a clerical job in the City. His opinions would be moderate, his expectations mildly optimistic, and his indulgences quiet and frugal. He would read newspapers but not appear in them.

On the bus to Clapham today you will sit between an investment banker, who is going to triple-lock herself into her bleak apartment before microwaving some Lean Cuisine; and an unemployed Muslim youth who is going to hang out on the streets with his friends before being stopped and searched by the police for the ninth time in the past six months. Either of them (for Britain does not have summary objection) could end up on the jury that tries your case. Which of them is the “reasonable person”?

Most studies of jury deliberation suggest that jurors make decisions intuitively, swiftly, and in relation to themselves. They create a
story
that revolves around personalities rather than evidence. The author of “He's a cold-hearted killer who planned this all ahead of time” has heard the same facts as the man who sees “Basically a nice guy who got into a situation that was too much for him.” Once a story has taken shape, a juror assesses evidence in terms of it. The twelve jurors will each fill in gaps with causes and motivations supplied from their own experience: in effect, they create their own probability. This is where Aristotle's model breaks down and rhetoric earns its bad reputation, as the smart lawyer plays to the assumptions of each type, not to a shared sense of law or likelihood.

As jurors, though, our job is to decide on the facts; so why aren't we allowed the tools to do so? Why are there laws of evidence restricting what can come to court? Why are we not given a briefing on legal issues by the judge in plain language before the trial begins? Why, instead of being a randomly chosen jury of peers, are we selected from a sociological shopping list? And why—since many true conclusions are counterintuitive—are we denied instruction in the forms of probability that let us refine our intuition? How else, in this complex and unpredictable world, will we know what usually happens?

Certainty is the song the sirens sang; but probability is a tune we all could learn without danger—not as a substitute for common sense, but as a check on it. Law is a succession of likelihood problems, no two the same, with every possible flaw of evidence and presentation. Yet we need not depend solely on raw instinct, rhetoric, or prejudice to solve them: we have methods to refine our opinions and bring the likely out of the mass of possibility. As the great lawyer Robert Ingersoll warned a jury in 1891: “Naturalness, and above all, probability, is the test of truth. Probability is the torch that every juryman should hold, and by the light of that torch he should march to his verdict. Probability!”

9

Predicting

 

 

 

 

 

T
oday the rain falls in a series of receding planes; yesterday the sun saw everything, blazing from a porcelain-blue sky touched up with stratocirrus by the best Italian ceiling painters. This window has framed afternoons when the blind fog wiped its dripping nose against the glass; roaring nights when a runaway westerly bucketed by; and stunned, reverent mornings of first snow with crows speckled calligraphically across the silent fields.

When the English begin all conversations with a discussion of the weather, it is a way of gossiping, without vulgarity, about the most dynamic personality they know. The weather is an ever-present but capricious lover, alternating moments of heart-lifting generosity with flashes of devastating temper. Earth is potential, weather is action; we propitiate the goddess—we watch out for the god.

The lines are from Hesiod's
Works and Days,
a poetic compendium of useful rural knowledge. A
very
old farmer's almanac, it tells the days to begin planting, pruning, and threshing, and explains how evil came into the world. Hesiod, himself a Boeotian shepherd, believed entirely in the interrelatedness of these things—yet any farmer can tell you that one year is very different from another. Less piously accepting minds began to wonder: was Zeus responsible for the consistency or the inconsistency? Theophrastus, Aristotle's student and successor, wrote extensively about the wind, thunder, and lightning, but denied their divine origin: capriciousness could not be the work of God, the fountain of order.

 

The classical world's ambivalence about the weather reflected a familiar division between the comforts of universal divine causality and the uneasiness of scientific doubt. Opting for comfort was the poet Aratus, whose
Phenomena
—a cobbling together of borrowed astronomy, conventional piety, and folk weather-lore—was the most copied work after the
Iliad
and the
Odyssey
. In the
Phenomena,
God is everywhere: “red sky at night, shepherd's delight,” for instance, is one of His assurances—not, perhaps, as strong a covenant as the rainbow, but still useful.

On the other side, we have the early scientific meteorologists, the heirs of Theophrastus. They were bothered not just by Zeus' thunderbolts hitting his own temples, but by the too easy linking of remote phenomena. Seneca applauded the people of Cleonae for appointing “hail officers”; but what happened when the officers reported an approaching storm? Everyone sacrificed an animal—and, in Seneca's deadpan report, “Once these clouds had tasted some blood, they moved off.” Correlation is not causation: the Dog Star's rising need not be the reason for August's heat. Vast and distant doings are made ridiculous by our attempts to assign cause.

These skeptics also felt that, if these things were purely material, they should fit with current ideas about the nature of matter: snow, for instance, could be understood as water combined with air. Aristotle's
Meteorology
proposed that the best analogy might be the body, with its fevers and chills; earthquakes might be a kind of terrestrial flatulence. But still nothing helped predict the weather. The philosophers could predict eclipses years in advance, but could not tell you if it would rain tomorrow.

 

All traditional weather signs bind together qualities: the iodine smell that presages an onshore blow, unbrushable static-electric hair before a deep chill. These qualities may each be significant, explicable and true, but you cannot make a science out of them because you cannot link one phenomenon to another. Their currencies are not mutually convertible. But by isolating the qualities that can be expressed as number, you gain a way to transfer and repeat at least
some
elements of experience.

It was Galileo who began the process of catching hold of weather by determining what to measure and devising tools to do so. He gave us the thermometer and our first idea of the atmosphere as a liquid, with its own weight and inertia. In 1642, Torricelli, trying to improve the vacuum pump, discovered that an evacuated glass tube placed mouth down in a dish of mercury drew the metal up its length to a point of stasis, where the weight of mercury raised must equal the pressure of air over the same area. Seven years later, the young Pascal persuaded his brother-in-law to take one of Torricelli's tubes up a mountain, demonstrating by repeated measurements during the ascent that atmospheric pressure was a function of the weight of air above us. Sir Christopher Wren had meanwhile invented a wind-speed measuring device, in the form of (and no doubt inspired by) a swinging shop sign.

Time, temperature, pressure, speed—almost all the elements of the modern weather report were in place by the middle of the seventeenth century. And once there was something to measure, fascinating relations between these measurements appeared. Boyle showed how pressure, volume, and temperature could be converted into one another. Joseph Black isolated CO
₂
from air; Rutherford nitrogen; Priestley oxygen. Lavoisier defined the atmosphere as these gases plus water vapor—missing only the inert gases such as helium, argon, and neon. The turn of the nineteenth century saw cloud classification, methods of measuring humidity, and an understanding of the role of water vapor in the transfer of heat energy. At a local level—isolated in brass cylinders and glass tubes—the atmosphere was revealing its secret mechanism.

Did all this improve weather forecasting? Sadly, no. Any householder with a barometer would now have its evidence that storms were on their way—but he would already have known as much because his knee ached and the cat had gone down to the cellar. Understanding the global atmosphere would require global data.

The explorer-naturalist Alexander von Humboldt appears in a painting of 1799, sitting under a palm on the coast of Venezuela in a gorgeous peach silk waistcoat, contemplating the sunrise over the mirror-smooth Caribbean. Yet even in this moment of tropical leisure, his copper barometer—servant and master—stands rigidly at his side. Humboldt had begun his regular meteorological observations in 1797 in the Tyrol, fixing the mountaintops with his twelve-inch sextant and staying out all night to record, at regular intervals, the air's pressure, temperature, humidity, oxygen and carbon-dioxide content, and electrical charge.

Von Humboldt's mission was to “find out about the unity of nature.” He pursued this goal through a lifetime's passionate observation; and, thanks to his great personal charm and integrity, he was able to mobilize international power to gather global data. He persuaded the Tsar to set up across his whole empire a chain of meteorological stations that could take uniform measurements at the same moment. The President of Britain's Royal Society, the Duke of Sussex, had been a friend of Humboldt's student days: one letter to him assured the creation of observatories in Canada, Jamaica, Saint Helena, South Africa, Ceylon, New Zealand, and Australia, as well as the fitting out of the naval expedition that surveyed the Antarctic and gave its name to the Ross Ice Shelf. All these observers contributed wonderfully complete and consistent data (except for the Royal Artillery detachment in Tasmania, which refused to make observations on the Sabbath).