Bully for Brontosaurus (48 page)

The following homily may seem paradoxical, but it embodies Hutton’s wisdom: The best science often proceeds by putting aside the overarching generality and focusing instead on a smaller question that can be reliably answered. In so doing, scientists show their intuitive feel for the fruitful, not their narrowness or paltriness of spirit. In this way we sneak up on big questions that only repel us if we try to engulf them in one fell speculation. Newton could not discover the nature of gravity, but he could devise a mathematics that unified the motion of a carriage with the revolution of the moon (and the drop of an apple). Darwin never tried to grasp the meaning of life (or even the manner of its origin on our planet), but he did develop a powerful theory to explain its manner of change through time. Hutton did not discover how our earth originated, but he developed some powerful and testable ideas about how it ticked. You might almost define a good scientist as a person with the horse sense to discern the largest answerable question—and to shun useless issues that sound grander.

Hutton’s positive principle of restriction to the doable also defines the domain and procedures of evolutionary biology, my own discipline. Evolution is not the study of life’s ultimate origin as a path toward discerning its deepest meaning. Evolution, in fact, is not the study of origins at all. Even the more restricted (and scientifically permissible) question of life’s origin on our earth lies outside its domain. (This interesting problem, I suspect, falls primarily within the purview of chemistry and the physics of self-organizing systems.) Evolution studies the pathways and mechanisms of organic change following the origin of life. Not exactly a shabby subject either—what with such resolvable questions as “How, when, and where did humans evolve?” “How do mass extinction, continental drift, competition among species, climatic change, and inherited constraints of form and development interact to influence the manner and rate of evolutionary change?” and “How do the branches of life’s tree fit together?” to mention just a few among thousands equally exciting.

In their recently aborted struggle to inject Genesis literalism into science classrooms, fundamentalist groups followed their usual opportunistic strategy of arguing two contradictory sides of a question when a supposed rhetorical advantage could be extracted from each. Their main pseudoargument held that Genesis literalism is not religion at all, but really an alternative form of science not acknowledged by professional biologists too hidebound and dogmatic to appreciate the cutting edge of their own discipline. When we successfully pointed out that “creation science”—as an untestable set of dogmatic proposals—could not qualify as science by any standard definition, they turned around and shamelessly argued the other side. (They actually pulled off the neater trick of holding both positions simultaneously.) Now they argued that, yes indeed, creation science is religion, but evolution is equally religious.

To support this dubious claim, they tumbled (as a conscious trick of rhetoric, I suspect) right into Kirwan’s error. They ignored what evolutionists actually do and misrepresented our science as the study of life’s ultimate origin. They then pointed out, as Hutton had, that questions of ultimate origins are not resolvable by science. Thus, they claimed, creation science and evolution science are symmetrical—that is, equally religious. Creation science isn’t science because it rests upon the untestable fashioning of life
ex nihilo
by God. Evolution science isn’t science because it tries, as its major aim, to resolve the unresolvable and ultimate origin of life. But we do no such thing. We understand Hutton’s wisdom—“he has nowhere treated of the first origin…of any substance…but only of the transformations which bodies have undergone…”

Our legal battle with creationists started in the 1920s and reached an early climax with the conviction of John Scopes in 1925. After some quiescence, the conflict began in earnest again during the 1970s and has haunted us ever since. Finally, in June 1987, the Supreme Court ended this major chapter in American history with a decisive 7–2 vote, striking down the last creationist statute, the Louisiana equal time act, as a ruse to inject religion into science classrooms in violation of First Amendment guarantees for separation of church and state.

I don’t mean to appear ungrateful, but we fallible humans are always seeking perfection in others. I couldn’t help wondering how two justices could have ruled the other way. I may not be politically astute, but I am not totally naive either. I have read Justice Scalia’s long dissent carefully, and I recognize that its main thrust lies in legal issues supporting the extreme judicial conservatism espoused by Scalia and the other dissenter, Chief Justice Rehnquist. Nonetheless, though forming only part of his rationale, Scalia’s argument relies crucially upon a false concept of science—Kirwan’s error again. I regret to say that Justice Scalia does not understand the subject matter of evolutionary biology. He has simply adopted the creationists’ definition and thereby repeated their willful mistake.

Justice Scalia writes, in his key statement on scientific evidence:

I simply don’t see the point of this statement. Of course they are so entitled, and absolutely nothing prevents such a presentation, if evidence there be. The equal time law forces teaching of creation science, but nothing prevented it before, and nothing prevents it now. Teachers were, and still are, free to teach creation science. They don’t because they recognize it as a ruse and a sham.

Scalia does acknowledge that the law would be unconstitutional if creation science is free of evidence—as it is—and if it merely restates the Book of Genesis—as it does:

Scalia therefore admits that the issue is not merely legal and does hinge on a question of scientific fact. He then buys the creationist argument and denies that we have sufficient evidence to render this judgment of unconstitutionality. Continuing directly from the last statement, he writes:

But this is exactly what I, and all scientists, do say. We are not blessed with absolute certainty about any fact of nature, but evolution is as well confirmed as anything we know—surely as well as the earth’s shape and position (and we don’t require equal time for flat-earthers and those who believe that our planet resides at the center of the universe). We have oodles to learn about how evolution happened, but we have adequate proof that living forms are connected by bonds of genealogical descent.

So I asked myself, how could Justice Scalia be so uninformed about the state of our basic knowledge? And then I remembered something peculiar that bothered me, but did not quite register, when I first read his dissent. I went back to his characterization of evolution and what did I find (repeated, by the way, more than a dozen times, so we know that the argument represents no onetime slip of his pen, but a consistent definition)?

Justice Scalia has defined evolution as the search for life’s origin—and nothing more. He keeps speaking about “the current state of scientific evidence about the origin of life” when he means to designate evolution. He writes that “the legislature wanted to ensure that students would be free to decide for themselves how life began based upon a fair and balanced presentation of the scientific evidence.” Never does he even hint that evolution might be the study of how life changes after it originates—the entire panoply of transformation from simple molecules to all modern, multicellular complexity.

Moreover, to make matters worse, Scalia doesn’t even acknowledge the scientific side of the origin of life on earth. He argues that a creationist law might have a secular purpose so long as we can envisage a concept of creation not involving a personal God “who is the object of religious veneration.” He then points out that many such concepts exist, stretching back to Aristotle’s notion of an unmoved mover. In the oral argument before the Court, which I attended on December 10, 1986, Scalia pressed this point even more forcefully with counsel for our side. He sparred:

Following this theme, Scalia presents his most confused statement in the written dissent:

True indeed; one might be a creationist in some vernacular sense by maintaining a highly abstract and impersonal view of a creator. But Aristotle’s unmoved mover is no more part of science than the Lord of Genesis. Science does not deal with questions of ultimate origins. We would object just as strongly if the Aristotelophiles of Delaware forced a law through the state legislature requiring that creation of each species
ex nihilo
by an unmoved mover be presented every time evolution is discussed in class. The difference lies only in historical circumstance, not the logic of argument. The unmoved mover doesn’t pack much political punch; fundamentalism ranks among our most potent irrationalisms.

Consider also, indeed especially, Scalia’s false concept of science. He equates creation and evolution because creationists can’t explain life’s beginning, while evolutionists can’t resolve the ultimate origin of the inorganic components that later aggregated to life. But this inability is the very heart of creationist logic and the central reason why their doctrine is not science, while science’s inability to specify the ultimate origin of matter is irrelevant because we are not trying to do any such thing. We know that we can’t, and we don’t even consider such a question as part of science.

We understand Hutton’s wisdom. We do not search for unattainable ultimates. We define evolution, using Darwin’s phrase, as “descent with modification” from prior living things. Our documentation of life’s evolutionary tree records one of science’s greatest triumphs, a profoundly liberating discovery on the oldest maxim that truth can make us free. We have made this discovery by recognizing what can be answered and what must be left alone. If Justice Scalia heeded our definitions and our practices, he would understand why creationism cannot qualify as science. He would also, by the way, sense the excitement of evolution and its evidence; no person of substance could be unmoved by something so interesting. Only Aristotle’s creator may be so impassive.

Don Quixote recognized “no limits but the sky,” but became thereby the literary embodiment of unattainable reverie. G. K. Chesterton understood that any discipline must define its borders of fruitfulness. He spoke for painting, but you may substitute any creative enterprise: “Art is limitation: the essence of every picture is the frame.”

MY FATHER
was a court stenographer. At his less than princely salary, we watched Yankee games from the bleachers or high in the third deck. But one of the judges had season tickets, so we occasionally sat in the lower boxes when hizzoner couldn’t attend. One afternoon, while DiMaggio was going 0 for 4 against, of all people, the lowly St. Louis Browns, the great man fouled one in our direction. “Catch it, Dad,” I screamed. “You never get them,” he replied, but stuck up his hand like the Statue of Liberty—and the ball fell right in. I mailed it to DiMaggio, and, bless him, he actually sent the ball back, signed and in a box marked “insured.” Insured, that is, to make me the envy of the neighborhood, and DiMaggio the model and hero of my life.

I met DiMaggio a few years ago on a small playing field at the Presidio of San Francisco. My son, wearing DiMaggio’s old number 5 on his Little League jersey, accompanied me, exactly one generation after my father caught that ball. DiMaggio gave him a pointer or two on batting and then signed a baseball for him. One generation passeth away, and another generation cometh: But the earth abideth forever.

My son, uncoached by Dad, and given the chance that comes but once in a lifetime, asked DiMaggio as his only query about life and career: “Suppose you had walked every time up during one game of your 56-game hitting streak? Would the streak have been over?” DiMaggio replied that, under 1941 rules, the streak would have ended, but that this unfair statute has since been revised, and such a game would not count today.

My son’s choice for a single question tells us something vital about the nature of legend. A man may labor for a professional lifetime, especially in sport or in battle, but posterity needs a single transcendant event to fix him in permanent memory. Every hero must be a Wellington on the right side of his personal Waterloo; generality of excellence is too diffuse. The unambiguous factuality of a single achievement is adamantine. Detractors can argue forever about the general tenor of your life and works, but they can never erase a great event.

In 1941, as I gestated in my mother’s womb, Joe DiMaggio got at least one hit in each of 56 successive games. Most records are only incrementally superior to runners-up; Roger Maris hit 61 homers in 1961, but Babe Ruth hit 60 in 1927 and 59 in 1921, while Hank Greenberg (1938) and Jimmy Foxx (1932) both hit 58. But DiMaggio’s 56-game hitting streak is ridiculously, almost unreachably far from all challengers (Wee Willie Keeler and Pete Rose, both with 44, come second). Among sabermetricians (a happy neologism based on an acronym for members of the Society for American Baseball Research, and referring to the statistical mavens of the sport)—a contentious lot not known for agreement about anything—we find virtual consensus that DiMaggio’s 56-game hitting streak is the greatest accomplishment in the history of baseball, if not all modern sport.

The reasons for this respect are not far to seek. Single moments of unexpected supremacy—Johnny Vander Meer’s back-to-back no-hitters in 1938, Don Larsen’s perfect game in the 1956 World Series—can occur at any time to almost anybody, and have an irreducibly capricious character. Achievements of a full season—such as Maris’s 61 homers in 1961 and Ted Williams’s batting average of .406, also posted in 1941 and not equaled since—have a certain overall majesty, but they don’t demand unfailing consistency every single day; you can slump for a while, so long as your average holds. But a streak must be absolutely exceptionless; you are not allowed a single day of subpar play, or even bad luck. You bat only four or five times in an average game. Sometimes two or three of these efforts yield walks, and you get only one or two shots at a hit. Moreover, as tension mounts and notice increases, your life becomes unbearable. Reporters dog your every step; fans are even more intrusive than usual (one stole DiMaggio’s favorite bat right in the middle of his streak). You cannot make a single mistake.

Thus Joe DiMaggio’s 56-game hitting streak is both the greatest factual achievement in the history of baseball and a principal icon of American mythology. What shall we do with such a central item of our cultural history?

Statistics and mythology may strike us as the most unlikely of bedfellows. How can we quantify Caruso or measure
Middlemarch
? But if God could mete out heaven with the span (Isaiah 40:12), perhaps we can say something useful about hitting streaks. The statistics of “runs,” defined as continuous series of good or bad results (including baseball’s streaks and slumps), is a well-developed branch of the profession, and can yield clear—but wildly counterintuitive—results. (The fact that we find these conclusions so surprising is the key to appreciating DiMaggio’s achievement, the point of this article, and the gateway to an important insight about the human mind.)

Start with a phenomenon that nearly everyone both accepts and considers well understood—“hot hands” in basketball. Now and then, someone just gets hot, and can’t be stopped. Basket after basket falls in—or out as with “cold hands,” when a man can’t buy a bucket for love or money (choose your cliché). The reason for this phenomenon is clear enough: It lies embodied in the maxim, “When you’re hot, you’re hot; and when you’re not, you’re not.” You get that touch, build confidence; all nervousness fades, you find your rhythm;
swish, swish, swish
. Or you miss a few, get rattled, endure the booing, experience despair; hands start shaking and you realize that you shoulda stood in bed.

Everybody knows about hot hands. The only problem is that no such phenomenon exists. Stanford psychologist Amos Tversky studied every basket made by the Philadelphia 76ers for more than a season. He found, first of all, that the probability of making a second basket did not rise following a successful shot. Moreover, the number of “runs,” or baskets in succession, was no greater than what a standard random, or coin-tossing, model would predict. (If the chance of making each basket is 0.5, for example, a reasonable value for good shooters, five hits in a row will occur, on average, once in 32 sequences—just as you can expect to toss five successive heads about once in 32 times, or 0.5
⁵
.)

Of course Larry Bird, the great forward of the Boston Celtics, will have more sequences of five than Joe Airball—but not because he has greater will or gets in that magic rhythm more often. Larry has longer runs because his average success rate is so much higher, and random models predict more frequent and longer sequences. If Larry shoots field goals at 0.6 probability of success, he will get five in a row about once every 13 sequences (0.6
⁵
). If Joe, by contrast, shoots only 0.3, he will get his five straight only about once in 412 times. In other words, we need no special explanation for the apparent pattern of long runs. There is no ineffable “causality of circumstance” (to coin a phrase), no definite reason born of the particulars that make for heroic myths—courage in the clinch, strength in adversity, etc. You only have to know a person’s ordinary play in order to predict his sequences. (I rather suspect that we are convinced of the contrary not only because we need myths so badly, but also because we remember the successes and simply allow the failures to fade from memory. More on this later.) But how does this revisionist pessimism work for baseball?

My colleague Ed Purcell, Nobel laureate in physics but, for purposes of this subject, just another baseball fan, has done a comprehensive study of all baseball streak and slump records. His firm conclusion is easily and swiftly summarized. Nothing ever happened in baseball above and beyond the frequency predicted by coin-tossing models. The longest runs of wins or losses are as long as they should be, and occur about as often as they ought to. Even the hapless Orioles, at 0 and 21 to start the 1988 season, only fell victim to the laws of probability (and not to the vengeful God of racism, out to punish major league baseball’s only black manager).
^*

But “treasure your exceptions,” as the old motto goes. Purcell’s rule has but one major exception, one sequence so many standard deviations above the expected distribution that it should never have occurred at all: Joe DiMaggio’s 56-game hitting streak in 1941. The intuition of baseball aficionados has been vindicated. Purcell calculated that to make it likely (probability greater than 50 percent) that a run of even 50 games will occur once in the history of baseball up to now (and 56 is a lot more than 50 in this kind of league), baseball’s rosters would have to include either four lifetime .400 batters or 52 lifetime .350 batters over careers of 1,000 games. In actuality, only three men have lifetime batting averages in excess of .350, and no one is anywhere near .400 (Ty Cobb at .367, Rogers Hornsby at .358, and Shoeless Joe Jackson at .356). DiMaggio’s streak is the most extraordinary thing that ever happened in American sports. He sits on the shoulders of two bearers—mythology and science. For Joe DiMaggio accomplished what no other ballplayer has done. He beat the hardest taskmaster of all, a woman who makes Nolan Ryan’s fastball look like a cantaloupe in slow motion—Lady Luck.

A larger issue lies behind basic documentation and simple appreciation. For we don’t understand the truly special character of DiMaggio’s record because we are so poorly equipped, whether by habits of culture or by our modes of cognition, to grasp the workings of random processes and patterning in nature.

Omar Khayyám, the old Persian tentmaker, understood the quandary of our lives (
Rubaiyat of Omar Khayyám
, Edward Fitzgerald, trans.):

But we cannot bear it. We must have comforting answers. We see pattern, for pattern surely exists, even in a purely random world. (Only a highly nonrandom universe could possibly cancel out the clumping that we perceive as pattern. We think we see constellations because stars are dispersed at random in the heavens, and therefore clump in our sight—see Essay 17.) Our error lies not in the perception of pattern but in automatically imbuing pattern with meaning, especially with meaning that can bring us comfort, or dispel confusion. Again, Omar took the more honest approach:

We, instead, have tried to impose that “heart’s desire” upon the actual earth and its largely random patterns (Alexander Pope,
Essay on Man
, end of Epistle 1):

Sorry to wax so poetic and tendentious about something that leads back to DiMaggio’s hitting streak, but this broader setting forms the source of our misinterpretation. We believe in “hot hands” because we must impart meaning to a pattern—and we like meanings that tell stories about heroism, valor, and excellence. We believe that long streaks and slumps must have direct causes internal to the sequence itself, and we have no feel for the frequency and length of sequences in random data. Thus, while we understand that DiMaggio’s hitting streak was the longest ever, we don’t appreciate its truly special character because we view all the others as equally patterned by cause, only a little shorter. We distinguish DiMaggio’s feat merely by quantity along a continuum of courage; we should, instead, view his 56-game hitting streak as a unique assault upon the otherwise unblemished record of Dame Probability.

Amos Tversky, who studied “hot hands,” has performed, with Daniel Kahneman, a series of elegant psychological experiments. These long-term studies have provided our finest insight into “natural reasoning” and its curious departure from logical truth. To cite an example, they construct a fictional description of a young woman: “Linda is 31 years old, single, outspoken, and very bright. She majored in philosophy. As a student, she was deeply concerned with issues of discrimination and social justice, and also participated in anti-nuclear demonstrations.” Subjects are then given a list of hypothetical statements about Linda: They must rank these in order of presumed likelihood, most to least probable. Tversky and Kahneman list eight statements, but five are a blind, and only three make up the true experiment:

Now it simply must be true that the third statement is least likely, since any conjunction has to be less probable than either of its parts considered separately. Everybody can understand this when the principle is explained explicitly and patiently. But all groups of subjects, sophisticated students who have pondered logic and probability as well as folks off the street corner, rank the last statement as more probable than the second. (I am particularly fond of this example because I know that the third statement is least probable, yet a little homunculus in my head continues to jump up and down, shouting at me—“but she can’t just be a bank teller; read the description.”)

Why do we so consistently make this simple logical error? Tversky and Kahneman argue, correctly I think, that our minds are not built (for whatever reason) to work by the rules of probability, though these rules clearly govern our universe. We do something else that usually serves us well, but fails in crucial instances: We “match to type.” We abstract what we consider the “essence” of an entity, and then arrange our judgments by their degree of similarity to this assumed type. Since we are given a “type” for Linda that implies feminism, but definitely not a bank job, we rank any statement matching the type as more probable than another that only contains material contrary to the type. This propensity may help us to understand an entire range of human preferences, from Plato’s theory of form to modern stereotyping of race or gender.