But for many questions in science, you can rerun the event as many times as you like, examine it in new ways, test a wide range of alternative hypotheses. When new tools are devised, you can perform the experiment again and see what emerges from your improved sensitivity. In those historical sciences where you cannot arrange a rerun, you can examine related cases and begin to recognize their common components. We can’t make stars explode at our convenience, nor can we repeatedly evolve through many trials a mammal from its ancestors. But we can simulate some of the physics of supernova explosions in the laboratory, and we can compare in staggering detail the genetic instructions of mammals and reptiles.
The claim is also sometimes made that science is as arbitrary or irrational as all other claims to knowledge, or that reason itself is an illusion. The American revolutionary, Ethan Alien – leader of the Green Mountain Boys in their capture of Fort Ticonderoga -had some words on this subject:
Those who invalidate reason ought seriously to consider whether they argue against reason with or without reason; if with reason, then they establish the principle that they are laboring to dethrone: but if they argue without reason (which, in order to be consistent with themselves they must do), they are out of reach of rational conviction, nor do they deserve a rational argument.
The reader can judge the depth of this argument.
Anyone who witnesses the advance of science first-hand sees an intensely personal undertaking. There are always a few – driven by simple wonder and great integrity, or by frustration with the inadequacies of existing knowledge, or simply upset with themselves for their imagined inability to understand what everyone else can – who proceed to ask the devastating key questions. A few saintly personalities stand out amidst a roiling sea of jealousies, ambition, backbiting, suppression of dissent, and absurd conceits. In some fields, highly productive fields, such behaviour is almost the norm.
I think all that social turmoil and human weakness aids the enterprise of science. There is an established framework in which any scientist can prove another wrong and make sure everyone else knows about it. Even when our motives are base, we keep stumbling on something new.
The American chemistry Nobel laureate Harold C. Urey once confided to me that as he got older (he was then in his seventies), he experienced increasingly concerted efforts to prove him wrong. He described it as ‘the fastest gun in the West’ syndrome: the young man who could outdraw the celebrated old gunslinger would inherit his reputation and the respect paid to him. It was annoying, he grumbled, but it did help direct the young whipper-snappers into important areas of research that they would never have entered on their own.
Being human, scientists also sometimes engage in observational selection: they like to remember those cases when they’ve been right and forget when they’ve been wrong. But in many instances, what is ‘wrong’ is partly right, or stimulates others to find out what’s right. One of the most productive astrophysicists of our time has been Fred Hoyle, responsible for monumental contributions to our understanding of the evolution of stars, the synthesis of the chemical elements, cosmology and much else. Sometimes he’s succeeded by being right before anyone else even understood that there was something that needed explaining. Sometimes he’s succeeded by being wrong – by being so provocative, by suggesting such outrageous alternatives that the observers and experimentalists feel obliged to check it out. The impassioned and concerted effort to ‘prove Fred wrong’ has sometimes failed and sometimes succeeded. In almost every case, it has pushed forward the frontiers of knowledge. Even Hoyle at his most outrageous -for example, proposing that the influenza and HIV viruses are dropped down on Earth from comets, and that interstellar dust grains are bacteria – has led to significant advances in knowledge (although turning up nothing to support those particular notions.)
It might be useful for scientists now and again to list some of their mistakes. It might play an instructive role in illuminating and
demythologizing the process of science and in enlightening younger scientists. Even Johannes Kepler, Isaac Newton, Charles Darwin, Gregor Mendel and Albert Einstein made serious mistakes. But the scientific enterprise arranges things so that teamwork prevails: what one of us, even the most brilliant among us, misses, another of us, even someone much less celebrated and capable, may detect and rectify.
For myself, I’ve tended in past books to recount some of the occasions when I’ve been right. Let me here mention a few of the cases where I’ve been wrong: at a time when no spacecraft had been to Venus, I thought at first that the atmospheric pressure was several times that on Earth, rather than many tens of times. I thought the clouds of Venus were made mainly of water, when they turn out to be only 25 per cent water. I thought there might be plate tectonics on Mars, when close-up spacecraft observations now show hardly a hint of plate tectonics. I thought the highish infrared temperatures of Titan might be due to a sizeable greenhouse effect there; instead, it turns out, it is caused by a stratospheric temperature inversion. Just before Iraq torched the Kuwaiti oil wells in January 1991, I warned that so much smoke might get so high as to disrupt agriculture in much of South Asia; as events transpired, it was pitch black at noon and the temperatures dropped 4-6°C over the Persian Gulf, but not much smoke reached stratospheric altitudes and Asia was spared. I did not sufficiently stress the uncertainty of the calculations.
Different scientists have different speculative styles, some being much more cautious than others. As long as new ideas are testable and scientists are not overly dogmatic, no harm is done; indeed, considerable progress can be made. In the first four instances I’ve just mentioned where I was wrong, I was trying to understand a distant world from a few clues in the absence of thorough spacecraft investigations. In the natural course of planetary exploration more data come in, and we find an army of old ideas ploughed down by an armamentarium of new facts.
Postmodernists have criticized Kepler’s astronomy because it emerged out of his medieval, monotheistic religious views; Darwin’s evolutionary biology for being motivated by a wish to perpetuate the privileged social class from which he came, or to justify his supposed prior atheism; and so on. Some of these claims are just. Some are not. But why does it matter what biases and emotional predispositions scientists bring to their studies, so long as they are scrupulously honest and other people with different proclivities check their results? Presumably no one would argue that the conservative view on the sum of fourteen and twenty-seven differs from the liberal view, or that the mathematical function that is its own derivative is the exponential in the northern hemisphere but some other function in the southern. Any regular periodic function can be represented to arbitrary accuracy by a Fourier series in Muslim as well as in Hindu mathematics. Non-commutative algebras (where A times B does not equal B times A) are as self-consistent and meaningful for speakers of Indo-European languages as for speakers of Finno-Ugric. Mathematics might be prized or ignored, but it is equally true everywhere – independent of ethnicity, culture, language, religion, ideology.
Towards the opposite extreme, there are questions such as whether abstract expressionism can be ‘great’ art, or rap ‘great’ music; whether it’s more important to curb inflation or unemployment; whether French culture is superior to German culture; or whether prohibitions against murder should apply to the nation state. Here the questions are oversimple, or the dichotomies false, or the answers dependent on unspoken assumptions. Here local biases might very well determine the answers.
Where in this subjective continuum, from almost fully independent of cultural norms to almost wholly dependent on them, does science lie? Although issues of bias and cultural chauvinism certainly arise, and although its content is continually being refined, science is clearly much closer to mathematics than it is to fashion. The claim that its findings are in general arbitrary and biased is not merely tendentious, but specious.
The historians Joyce Appleby, Lynn Hunt and Margaret Jacob (in Telling the Truth About History, 1994) criticize Isaac Newton: he is said to have rejected the philosophical position of Descartes because it might challenge conventional religion and lead to social chaos and atheism. Such criticisms amount only to the charge that scientists are human. How Newton was buffeted by the intellectual currents of his time is of course of interest to the historian of ideas; but it has little bearing on the truth of his propositions. For them to be generally accepted, they must convince atheists and theists alike. This is just what happened.
Appleby and her colleagues claim that ‘When Darwin formulated his theory of evolution, he was an atheist and a materialist,’ and suggest that evolution was a product of a purported atheist agenda. They have hopelessly confused cause and effect. Darwin was about to become a minister of the Church of England when the opportunity to sail on HMS Beagle presented itself. His religious ideas, as he himself described them, were at the time highly conventional. He found every one of the Anglican Articles of Faith entirely believable. Through his interrogation of Nature, through science, it slowly dawned on him that at least some of his religion was false. That’s why he changed his religious views.