by Carl Sagan
Here are the possible outcomes:
If you deny committing the crime and (unknown to you) your friend also denies it, the case might be hard to prove. In the plea bargain, both your sentences will be very light.
If you confess and your friend does likewise, then the effort the State had to expend to solve the crime was small. In exchange you both may be given a fairly light sentence, although not as light as if you both had asserted your innocence.
But if you plead innocent and your friend confesses, the state will ask for the maximum sentence for you and minimal punishment (maybe none) for your friend. Uh-oh. You’re very vulnerable to a kind of double cross, what game theorists call “defection.” So’s he.
So if you and your friend “cooperate” with one another—both pleading innocent (or both pleading guilty)—you both escape the worst. Should you play it safe and guarantee a middle range of punishment by confessing? Then, if your friend pleads innocent while you plead guilty, well, too bad for him, and you might get off scot-free.
When you think it through, you realize that whatever your friend does you’re better off defecting than cooperating. Maddeningly, the same holds true for your friend. But if you both defect, you’re both worse off than if you had both cooperated. This is the Prisoner’s Dilemma.
Now consider a repeated Prisoner’s Dilemma, in which the two players go through a sequence of such games. At the end of each they figure out from their punishment how the other must have pled. They gain experience about each other’s strategy (and character). Will they learn to cooperate game after game, both always denying that they committed any crime? Even if the reward for finking on the other is large?
You might try cooperating or defecting, depending on how the previous game or games have gone. If you cooperate overmuch, the other player may exploit your good nature. If you defect overmuch, your friend is likely to defect often, and this is bad for both of you. You know your defection pattern is data being fed to the other player. What is the right mix of cooperation and defection? How to behave then becomes, like any other question in Nature, a subject to be investigated experimentally.
This matter has been explored in a continuing round-robin computer tournament by the University of Michigan sociologist Robert Axelrod in his remarkable book The Evolution of Cooperation. Various codes of behavior confront one another and at the end we see who wins (who gets the lightest cumulative prison term). The simplest strategy might be to cooperate all the time, no matter how much advantage is taken of you, or never to cooperate, no matter what benefits might accrue from cooperation. These are the Golden Rule and the Iron Rule. They always lose, the one from a superfluity of kindness, the other from an overabundance of ruthlessness. Strategies slow to punish defection lose—in part because they send a signal that noncooperation can win. The Golden Rule is not only an unsuccessful strategy; it is also dangerous for other players, who may succeed in the short term only to be mowed down by exploiters in the long term.
Should you defect at first, but if your opponent cooperates even once, cooperate in all future games? Should you cooperate at first, but if your opponent defects even once, defect in all future games? These strategies also lose. Unlike sports, you cannot rely on your opponent to be always out to get you.
The most effective strategy in many such tournaments is called “Tit-for-Tat.” It’s very simple: You start out cooperating, and in each subsequent round simply do what your opponent did last time. You punish defections, but once your partner cooperates, you’re willing to let bygones be bygones. At first, it seems to garner only mediocre success. But as time goes on the other strategies defeat themselves, from too much kindness or cruelty, and this middle way pulls ahead. Except for always being nice on the first move, Tit-for-Tat is identical to the Brazen Rule. It promptly (in the very next game) rewards cooperation and punishes defection, and has the great virtue that it makes your strategy absolutely clear to your opponent. (Strategic ambiguity can be lethal.)
Once there get to be several players employing Tit-for-Tat, they rise in the standings together. To succeed, Tit-for-Tat strategists must find others who are willing to reciprocate, with whom they can cooperate. After the first tournament in which the Brazen Rule unexpectedly won, some experts thought the strategy too forgiving. Next tournament, they tried to exploit it by defecting more often. They always lost. Even experienced strategists tended to underestimate the power of forgiveness and reconciliation. Tit-for-Tat involves an interesting mix of proclivities: initial friendliness, willingness to forgive, and fearless retaliation. The superiority of the Tit-for-Tat Rule in such tournaments has been recounted by Axelrod.
TABLE OF PROPOSED RULES TO LIVE BY
The Golden Rule Do unto others as you would have them do unto you.
The Silver Rule Do not do unto others what you would not have them do unto you.
The Brazen (Brass) Rule Do unto others as they do unto you.
The Iron Rule Do unto others as you like, before they do it unto you.
The Tit-for-Tat Rule Cooperate with others first, then do unto them as they do unto you.
Something like it can be found throughout the animal kingdom and has been well-studied in our closest relatives, the chimps. Described and named “reciprocal altruism” by the biologist Robert Trivers, animals may do favors for others in expectation of having the favors returned—not every time, but often enough to be useful. This is hardly an invariable moral strategy, but it is not uncommon either. So there is no need to debate the antiquity of the Golden, Silver, and Brazen Rules, or Tit-for-Tat, and the priority of the moral prescriptives in the Book of Leviticus. Ethical rules of this sort were not originally invented by some enlightened human lawgiver. They go deep into our evolutionary past. They were with our ancestral line from a time before we were human.
The Prisoner’s Dilemma is a very simple game. Real life is considerably more complex. If he gives our apple to the pencil man, is my father more likely to get an apple back? Not from the pencil man; we’ll never see him again. But might widespread acts of charity improve the economy and give my father a raise? Or do we give the apple for emotional, not economic rewards? Also, unlike the players in an ideal Prisoner’s Dilemma game, human beings and nations come to their interactions with predispositions, both hereditary and cultural.
But the central lessons in a not very prolonged round-robin of Prisoner’s Dilemma are about strategic clarity; about the self-defeating nature of envy; about the importance of long-term over short-term goals; about the dangers of both tyranny and patsydom; and especially about approaching the whole issue of rules to live by as an experimental question. Game theory also suggests that a broad knowledge of history is a key survival tool.
CHAPTER 17
GETTYSBURG
AND NOW*
This speech was delivered on July 3, 1988 to approximately 30,000 people at the 125th celebration of the Battle of Gettysburg and the rededication of the Eternal Light Peace Memorial, Gettysburg National Military Park, Gettysburg, Pennsylvania. Every quarter century, the peace memorial at Gettysburg is rededicated; Presidents Wilson, Franklin Roosevelt and Eisenhower have been the previous speakers.
From Lend Me Your Ears: Great Speeches in History,
selected and introduced by William Safire
(New York: W. W. Norton, 1992)
Fifty-one thousand human beings were killed or wounded here—ancestors of some of us, brothers of us all. This was the first full-fledged example of an industrialized war, with machine-tooled arms and railroad transport of men and matériel. It was the first hint of an age yet to come, our age; an intimation of what technology bent to the purposes of war might be capable. The new Spencer repeating rifle was used here. In May 1863, a reconnaissance balloon of the Army of the Potomac detected movement of Confederate troops across the Rappahannock River, the beginning of the campaign that led to the Battle of Gettysburg. That balloon was a precursor of air forces and strategic bombing and reconnaissance satell
ites.
A few hundred artillery pieces were deployed in the three-day battle of Gettysburg. What could they do? What was war like then? Here is an eyewitness account by Frank Haskel of Wisconsin, who fought on this battlefield for the Union Armies, of nightmarish, apparently hovering, cannon balls. It is from a letter to his brother:
We could not often see the shell before it burst, but sometimes, as we faced towards the enemy and looked above our heads, the approach would be heralded by a prolonged hiss, which always seemed to me to be a line of something tangible terminating in a black globe distinct to the eye as the sound had been to the ear. The shell would seem to stop and hang suspended in the air an instant and then vanish in fire and smoke and noise.… Not ten yards away from us a shell burst among some bushes where sat three or four orderlies holding horses. Two of the men and one horse were killed.
It was a typical event from the Battle of Gettysburg. Something like this was repeated thousands of times. Those ballistic projectiles, launched from the cannons that you can see all over this Gettysburg Memorial, had a range, at best, of a few miles. The amount of explosive in the most formidable of them was some 20 pounds—roughly one-hundredth of a ton of TNT. It was enough to kill a few people.
But the most powerful chemical explosives used 80 years later, in World War II, were the blockbusters, so-called because they could destroy a city block. Dropped from aircraft, after a journey of hundreds of miles, each carried about 10 tons of TNT, a thousand times more than the most powerful weapon at the Battle of Gettysburg. A blockbuster could kill a few dozen people.
At the very end of World War II, the United States used the first atomic bombs to annihilate two Japanese cities. Each of those weapons, delivered after a voyage of sometimes a thousand miles, had the equivalent power of about 10,000 tons of TNT, enough to kill a few hundred thousand people. One bomb.
A few years later the United States and the Soviet Union developed the first thermonuclear weapons, the first hydrogen bombs. Some of them had an explosive yield equivalent to ten million tons of TNT; enough to kill a few million people. One bomb. Strategic nuclear weapons can now be launched to any place on the planet. Everywhere on Earth is a potential battlefield now.
Each of these technological triumphs advanced the art of mass murder by a factor of a thousand. From Gettysburg to the blockbuster, a thousand times more explosive energy; from the blockbuster to the atomic bomb, a thousand times more; and from the atomic bomb to the hydrogen bomb, a thousand times still more. A thousand times a thousand times a thousand is a billion; in less than one century, our most fearful weapon has become a billion times more deadly. But we have not become a billion times wiser in the generations that stretch from Gettysburg to us.
The souls that perished here would find the carnage of which we are now capable unspeakable. Today, the United States and the Soviet Union have booby-trapped our planet with almost 60,000 nuclear weapons. Sixty thousand nuclear weapons! Even a small fraction of the strategic arsenals could without question annihilate the two contending superpowers, probably destroy the global civilization, and possibly render the human species extinct. No nation, no man should have such power. We distribute these instruments of apocalypse all over our fragile world, and justify it on the grounds that it has made us safe. We have made a fool’s bargain.
The 51,000 casualties here at Gettysburg represented one-third of the Confederate Army, and one-quarter of the Union Army. All those who died, with one or two exceptions, were soldiers. The best-known exception was a civilian in her own house who thought to bake a loaf of bread and, through two closed doors, was shot to death; her name was Jennie Wade. But in a global thermonuclear war, almost all the casualties would be civilians—men, women, and children, including vast numbers of citizens of nations that had no part in the quarrel that led to the war, nations far removed from the northern midlatitude “target zone.” There would be billions of Jennie Wades. Everyone on Earth is now at risk.
In Washington there is a memorial to the Americans who died in the most recent major U.S. war, the one in Southeast Asia. Some 58,000 Americans perished, not a very different number from the casualties here at Gettysburg. (I ignore, as we too often do, the one or two million Vietnamese, Laotians, and Kampucheans who also died in that war.) Think of that dark, somber, beautiful, moving, touching memorial. Think of how long it is; actually, not much longer than a suburban street. 58,000 names. Imagine now that we are so foolish or inattentive as to permit a nuclear war to occur, and that, somehow, a similar memorial wall is built. How long would it have to be to contain the names of all those who will die in a major nuclear war? About a thousand miles long. It would stretch from here in Pennsylvania to Missouri. But, of course, there would be no one to build it, and few to read the roster of the fallen.
In 1945, at the close of World War II, the United States and the Soviet Union were virtually invulnerable. The United States—bounded east and west by vast and impassable oceans, north and south by weak and friendly neighbors—had the most effective armed forces, and the most powerful economy on the planet. We had nothing to fear. So we built nuclear weapons and their delivery systems. We initiated and vigorously pumped up an arms race with the Soviet Union. When we were done, all the citizens of the United States had handed their lives over to the leaders of the Soviet Union. Even today, post-Cold War, post-Soviet Union, if Moscow decides we should die, twenty minutes later we’re dead. In nearly perfect symmetry, the Soviet Union had the largest standing army in the world in 1945, and no significant military threats to worry about. It joined the United States in the nuclear arms race so that today everyone in Russia has handed their lives over to the leaders of the United States. If Washington decides they should die, twenty minutes later they’re dead. The lives of every American and every Russian citizen are now in the hands of a foreign power. I say we have made a fool’s bargain. We—we Americans, we Russians—have spent 43 years and vast national treasure in making ourselves exquisitely vulnerable to instant annihilation. We have done it in the name of patriotism and “national security,” so no one is supposed to question it.
Two months before Gettysburg, on May 3, 1863, there was a Confederate triumph, the battle of Chancellorsville. On the moonlit evening following the victory, General Stonewall Jackson and his staff, returning to the Confederate lines, were mistaken for Union cavalry. Jackson was shot twice in error by his own men. He died of his wounds.
We make mistakes. We kill our own.
There are some who claim that since we have not yet had an accidental nuclear war, the precautions being taken to prevent one must be adequate. But not three years ago we witnessed the disasters of the Challenger space shuttle and the Chernobyl nuclear power plant—high technology systems, one American, one Soviet, into which enormous quantities of national prestige had been invested. There were compelling reasons to prevent these disasters. In the preceding year, confident assertions were made by officials of both nations that no accidents of that sort could happen. We were not to worry. The experts would not permit an accident to happen. We have since learned that such assurances do not amount to much.
We make mistakes. We kill our own.
This is the century of Hitler and Stalin, evidence—if any were needed—that madmen can seize the reins of power of modern industrial states. If we are content in a world with nearly 60,000 nuclear weapons, we are betting our lives on the proposition that no present or future leaders, military or civilian—of the United States, the Soviet Union, Britain, France, China, Israel, India, Pakistan, South Africa, and whatever other nuclear powers there will be—will ever stray from the strictest standards of prudence. We are gambling on their sanity and sobriety even in times of great personal and national crisis—all of them, for all times to come. I say this is asking too much of us. Because we make mistakes. We kill our own.
The nuclear arms race and the attendant Cold War cost something. They don’t come free. Apart from the immense diversion of fiscal and intellect
ual resources away from the civilian economy, apart from the psychic cost of living out our lives under the Damoclean sword, what has been the price of the Cold War?
Between the beginning of the Cold War in 1946, and its end in 1989, the United States spent (in equivalent 1989 dollars) well over $10 trillion in its global confrontation with the Soviet Union. Of this sum, more than a third was spent by the Reagan Administration, which added more to the national debt than all previous administrations, back to George Washington, combined. At the beginning of the Cold War, the nation was, in all significant respects, untouchable by any foreign military force. Today, after the expenditure of this immense national treasure (and despite the end of the Cold War), the United States is vulnerable to virtually instant annihilation.
A business that spent its capital so recklessly, and with so little effect, would have been bankrupt long ago. Executives who could not recognize so clear a failure of corporate policy would long before now have been dismissed by the stockholders.
What else could the United States have done with that money (not all of it, because prudent defense is, of course, necessary—but, say, half of it)? For a little over $5 trillion, skillfully applied, we could have made major progress toward eliminating hunger, homelessness, infectious disease, illiteracy, ignorance, poverty, and safeguarding the environment—not just in the United States but worldwide. We could have helped make the planet agriculturally self-sufficient and removed many of the causes of violence and war. And this could have been done with enormous benefit to the American economy. We could have made deep inroads into the national debt. For less than a percent of that money, we could have mustered a long-term international program of manned exploration of Mars. Prodigies of human inventiveness in art, architecture, medicine, and science could be supported for decades with a tiny fraction of that money. The technological and entrepreneurial opportunities would have been prodigious.