Dreams of Earth and Sky (22 page)

In addition to the two legacies of discoveries and aesthetic principles, Dirac also left a third legacy, which I consider precious but Farmelo does not. This legacy is Dirac’s refusal to engage in philosophical arguments about the interpretation of quantum mechanics. These philosophical debates raged during his lifetime and have raged even more fiercely after his death. Dirac took no part in these debates and considered them to be meaningless. He said, as Galileo said three hundred years earlier, that mathematics is the language that nature speaks. When expressed in mathematical equations, the laws of quantum mechanics are clear and unambiguous. Confusion arises from misguided attempts to translate the laws from mathematics to human language.

Human language describes the world of everyday life and lacks the concepts that could describe quantum processes accurately. Dirac said we should stop arguing about words, stay with mathematics, and allow the philosophical fog to blow away. I consider Dirac’s disengagement from verbal disputes about the meaning of quantum mechanics to be an essential part of his legacy. But I am, as usual, in the minority.

Note added in 2014: In response to this review, I received a number of illuminating letters from friends and relatives of the Dirac family. I encouraged the authors to send copies of their letters to the Dirac archive, which is maintained at Florida State University at Tallahassee.

SINCE PEOPLE BEGAN
to wonder about human destiny, there have always been prophets of hope and prophets of doom. Long ago in Mesopotamia, as recorded in the book of Genesis, Abraham fell on his face and God talked with him, saying:

Abraham was the first prophet of hope in the Western tradition. He set the pattern of our culture. He was a traveler, moving into a new country to take possession of it for his descendants. A little later, other prophets of hope, Gautama Buddha and Lao Tse, started other traditions in other places. Meanwhile, in the West, Jeremiah the prophet of doom raised his voice in Jerusalem against Abraham:

Other prophets of doom proclaimed in other traditions the anger of gods and the helplessness of humans. The dialogue between Abraham and Jeremiah continues today. It is still one of the main themes of our history. So what is new?

One thing that is new is modern science. Science has not displaced religion as the way most people approach the problems of our destiny, but science allows us all to look at these problems in a new way. Francis Bacon, the major prophet of modern science in the British tradition, did not proclaim the word of the Lord but spoke with his own more modest voice: “If we begin with certainties, we will end in doubt, but if we begin with doubts and bear them patiently, we may end in certainty.”

Bacon was writing at the beginning of the seventeenth century, when religious wars were raging in Europe, when Pilgrim fathers filled with Abrahamic hopes were building a new world in America, when Puritan divines filled with visions of jeremiad doom were preaching hellfire and damnation. He offered a third alternative to the certainties of heaven and hell: the alternative of patient inquiry. He told us to ask questions instead of proclaiming answers, to collect evidence instead of rushing to judgment, to listen to the voice of nature rather than to the voice of ancient wisdom. Bacon predicted accurately the growth of modern science. In the centuries since he
wrote, modern science has transformed the problem of human destiny. Destiny is now no longer an unalterable fate, irreversibly good or evil. Destiny has become a continuing experiment in which we are free to learn from our mistakes.

In the modern world of life and death to which we all belong, a crucial problem of our destiny is the size of human populations. It seems to be a simple problem. How many people should there be? How many babies should we raise? But modern science has twice transformed the nature of the problem. In the eighteenth century, science started industrial and medical revolutions that caused a rapid growth of populations. In the twentieth century, science started social revolutions that caused an equally rapid decline of birth rates.

It was easy to understand, as Robert Malthus pointed out in his famous
Essay on the Principle of Population
in 1798, how new technology had caused population growth that might in turn cause a disproportionate growth of human misery. It is more difficult to understand, in the world of today, how birth rates fell rapidly in large parts of the world while remaining high in others. It appears that birth rates fell sharply for different reasons in different places, in China because of draconian rules imposed by the government, in Europe and America because a large fraction of women became educated and economically independent. Meanwhile, birth rates remain high in Africa and in parts of Asia where societies are maledominated and women are mostly illiterate.

Three facts emerge clearly from the history of the last three centuries. First, a huge experiment is in progress, exploring various ways of dealing with the problem of population. Second, no central authority is in charge. Third, the result of the experiment is still in doubt. Many kinds of disaster resulting from population explosion or population collapse are still possible. Nevertheless, the results of the experiment up to the present time are encouraging. The disasters
predicted by Malthus did not occur. Populations in several parts of the world with different political and ethical traditions were successfully controlled by different methods. It appears to be generally true that rising wealth and communication and education in any society produce a rapid fall in birth rates. This is an experimental conclusion, subject to criticism and correction. It does not tell us that the problem of population is finally solved. It tells us that the solution of the problem is still in our hands, to be explored by continued experiment and by correction of errors.

When we look to the remote future, the main problem of our destiny will not be the size of populations but their quality. Shall we remain a single species bound together by bonds of family and kinship, or shall we evolve into many diverse species as our vertebrate ancestors did in the past? Either alternative brings losses as well as gains. If we remain single, we lose vast opportunities to explore new ways of living and thinking. We lose the historic power of biological evolution to try out new experiments and to create new designs of body and mind. If we diversify, we lose the brotherhood of man. We lose the shared loyalties and traditions that made us what we are. By separating into alien species, we open endless possibilities of future strife and irreconcilable quarrels.

Perhaps these dangers can be mitigated if the diversification of human nature is combined with an expansion of our habitat from one planet to a multitude of communities spread out over the universe. Those of us who choose to stay on this planet should remain brothers, while those who choose to experiment with new creative possibilities should move far enough away that the failure of their experiments will not endanger those who stayed at home. The vastness of the universe allows us to dream of an infinite future for humanity, with bodies and minds spreading in space and expanding in quality far beyond anything that we can imagine. That is why David
Deutsch gave his book the title
The Beginning of Infinity.
*
The subtitle, “Explanations That Transform the World,” carries the central message of the book. It says that our destiny is to be explainers of the world around us, and explaining is the key to mastery.

Deutsch has an important message. He writes clearly and thinks wisely. His book could help to push the world toward better ways of dealing with its problems. It is written for concerned citizens and not only for philosophers. I hope many concerned citizens will read it and take its message to heart. Unfortunately, Deutsch is himself a philosopher, with a fondness for abstruse philosophical arguments. Fortunately, he puts his plain language and his abstruse philosophizing into separate chapters. The common reader should skip the technical chapters and pay attention to the others. The difficult chapters 11 and 12, “The Multiverse” and “A Physicist’s History of Bad Philosophy,” ought to have been published as a separate book, addressed to a different audience. They have little connection with the outstandingly lucid chapters 10 and 13, “A Dream of Socrates” and “Choices,” which stand immediately before and after them. The difficult chapters are for readers who share Deutsch’s view of the nature and purpose of philosophy.

Philosophy can be regarded as a branch of science or as a branch of literature. For Deutsch, philosophy is a collection of explanations and arguments that are either right or wrong. For me, philosophy is a collection of stories. For Deutsch, the only philosopher who deserves unconditional respect is Karl Popper, because he alone asked the right questions and gave them the right answers. For me, the great philosophers are those like Plato and Bertrand Russell who happen to be good writers. In one of his lighter moments Russell expressed a view of philosophy similar to mine: “Science is organized common
sense; philosophy is organized piffle.” In my view, Deutsch becomes a true philosopher when he forgets his technical arguments and tells evocative stories.

Deutsch sums up human destiny in two statements that he displays as inscriptions carved in stone: “problems are inevitable” and “problems are soluble.” His chapter “The Spark” introduces these statements and explains their meaning. They apply to all aspects of human activity, to ethics and law and religion as well as to art and science. In every area, from pure mathematics and logic to war and peace, there are no final solutions and no final impossibilities. He identifies the spark of insight, which gave us a clear view of our infinite future, with the beginning of the British Enlightenment in the seventeenth century. He makes a sharp distinction between the British Enlightenment and the Continental Enlightenment, which arose at the same time in France.

Both enlightenments began with the insight that problems are soluble. Both of them engaged the most brilliant minds of that age in the solution of practical problems. They diverged because many thinkers of the Continental Enlightenment believed that problems could be finally solved by utopian revolutions, while the British believed that problems were inevitable. According to Deutsch, Bacon transformed the world when he took the long view, foreseeing an infinite process of problem-solving guided by unpredictable successes and failures. Deutsch’s version of history is narrow. It is Whig history, portraying human destiny as a triumph of parochial British ideas and institutions.

Long before Bacon, thinkers in China were taking a long view of history and pushing it along a different path, and Socrates in Greece was teaching us to search for wisdom by asking questions rather than by knowing the answers. Many diverse cultures were converging to the conclusion that humans have a choice. If we want to, we can be
the spark, transforming the universe from a purposeless machine into a creative community of living creatures always asking new questions and struggling to find new answers.

Returning to present-day problems in his chapter “Choices,” Deutsch discusses politics and economics. Two questions have dominated the study of political economy in the past. How should we choose our rulers? And how unequally should we distribute wealth between rich and poor? In recent debates over the choice of rulers, people have usually asked the wrong question. They asked, who are the best rulers? They assumed that if this question were answered, then we should allow the best rulers to rule and the problem of good government would be solved.

But history taught us long ago that this is the wrong question. There are no best rulers, because power corrupts and circumstances change. Rulers often begin well and then make stupid mistakes. The English civil war between King Charles I and his Parliament demonstrated clearly that the concept of a best ruler was an illusion. The king, claiming to rule by divine right, abused his power flagrantly, and the parliamentary leaders rose in rebellion against him. The Parliament won the war, beheaded the king, and appointed Oliver Cromwell to rule in his place. When Cromwell died, the Parliament decided after all to invite the son of the murdered king back.

Chastened by defeat and exile, the new king ruled more gently and more wisely than either his father or Cromwell. During that century, the great debate between monarchy and republic was conducted on an extraordinarily high intellectual level. The two greatest poets of the English language were deeply engaged: William Shakespeare standing close to the monarchs Elizabeth and James, John Milton standing close to Cromwell. Shakespeare’s histories and tragedies held up the mirror to kings and queens. Milton’s
Areopagitica
held up the mirror to officeholders who try to rule our minds.

The right question to ask was not “Who are the best rulers?” but “How do we make sure that rulers can be peacefully replaced when they rule badly?” Democratic systems of government are designed to answer the latter question. Elections are held not to choose the best rulers but to give us a chance to get rid of the worst without bloodshed. Constitutional monarchy is another solution to the same problem. The present queen of England has no power to rule her country, but she has the power to dissolve Parliament and stop any politician from taking actions that are flagrantly unconstitutional. The perennial problem of government is not to choose the best rulers but to hold bad rulers responsible for their failures.