The Knowledge Machine: How Irrationality Created Modern Science

by Michael Strevens

The long absence of science is therefore not to be explained by some particular train of events or some specific mix of custom and circumstance. It spans democracies and theocracies, east and west, pantheists and People of the Book. It seems, to all the world, that there is something about the nature of science itself that the human race finds hard to take on board. That, I believe, is the answer: science is an alien thought form. To understand its late arrival on the human scene, we need to appreciate the inherent strangeness of the scientific method.

Science, by contrast, requires of its practitioners the strategic suppression of human nature, indeed, the suppression of the highest element of human nature, the rational mind.

That is the Kuhnian answer to the motivation problem: mold scientists’ minds so that they fail to see that their research might be based on an error, on a false presupposition. If the validity of the paradigm is accepted without question, then the value of long and arduous empirical toil is also beyond question. The purpose of narrowing scientists’ horizons is to encourage them to work harder, to dig deeper, to go further than they would go if they could see their destination in perspective, if they had an accurate sense of their project’s proportion. Ultimately, it is only because scientists’ faith in the paradigm guarantees the importance of their research that they feel secure enough to work the paradigm to death—to experiment in such detail, with such precision, as to expose the paradigm’s shortcomings, to drive science to a crisis, and so to establish the preconditions for revolution. This is Kuhn’s marvelous paradox: A paradigm can change only because the scientists working within it cannot imagine it changing. It is their certainty of its success that secures its destruction.

Science, in the radical subjectivist view, is just another venue for the Machiavellian masterpiece theater that is the human condition.

Science is driven onward by arguments between people who have made up their minds and want to convert or at least to confute their rivals. Opinion that runs hot-blooded ahead of established fact is the life force of scientific inquiry. For these reasons, Popper is now thought by most philosophers of science to fall short of providing a rule for bringing evidence to bear on theories that is both fully objective and adequate to science’s needs. What kind of rule might do better? There is philosophical consensus on this matter, too—and the answer is none. An objective rule for weighing scientific evidence is logically impossible. The impossibility arises from the same fact that makes Popperian falsification often such a contentious matter: a scientific theory issues predictions only when it is combined with various assumptions to compose a theoretical cohort. The members of the cohort—what philosophers call “auxiliary assumptions”—are a diverse range of suppositions.

The auxiliary assumptions are like links in a chain leading from the theory to the evidence. The chain is only as strong as its weakest link; thus, to assess the strength of the chain—to assess the strength of a piece of evidence for or against a hypothesis—you must have an opinion about the strength of each of the links.

A rule that strives to lay down the law about the significance of scientific evidence, then, must also lay down the law about the likelihood of all relevant auxiliary assumptions, in the same way that a procedure for determining chain strength must estimate the strength of every link. The rule’s judgments can be objectively valid only if its estimates of the auxiliary’s likelihoods are objectively valid. An objective rule for weighing any and every piece of evidence is therefore possible only if there is an objective fact of the matter about the likelihood of each relevant auxiliary assumption, given the available evidence.

So it goes with all scientific reasoning: the interpretation of evidence demands likelihoods, and scientists are not only permitted but encouraged to use their subjective plausibility rankings in that role.

Here, then, in short, is the iron rule: 1. Strive to settle all arguments by empirical testing. 2. To conduct an empirical test to decide between a pair of hypotheses, perform an experiment or measurement, one of whose possible outcomes can be explained by one hypothesis (and accompanying cohort) but not the other. There lies the nub of the scientific method and so, once its subtleties have been spelled out in the chapters to come, the denouement of the Great Method Debate.

Physics after Aristotle bifurcated into two schools, the Epicureans and the Stoics, the one affirming an atomistic view in which the universe is composed of nothing more than particles careening blindly through the emptiness of space, the other a view in which matter fills the universe according to the dictates of rationality. An individual seeking enlightenment while Stoicism and Epicureanism held sway, from about 300 BCE to 300 CE, could choose one school or the other or attempt to learn from both, but the schools themselves remained detached intellectual traditions, separated by both their physics and their philosophy of life, until economic decline, barbarian invasions, and Christianity finished them off.

As evidence accumulates, plausibility rankings begin to converge. Differences in opinion become less extreme. Consensus emerges as to which are the leading theoretical contenders and which are the also-rans, then eventually on which is the best of them all. There is not complete agreement, but there is ever less disagreement. This is Baconian convergence.

What happened in the case of general relativity, and what tends to happen in science more generally, is that opinions converge not because bad data is corrected but because it is swamped.

So we see that over the decades and centuries, agreement emerges again and again from the tissue of uncertainty and dissent that is the characteristic stuff of science—provided that everyone keeps arguing and the stock of observations continues to grow.

The historian David Lindberg provides a partial list of experimenters at work before the Scientific Revolution that stretches from the ancient Roman Empire to Islamic Persia through the European Middle Ages, including, among many others, Ptolemy, Ibn al-Haytham (Alhazen), Kamāl al-Dīn, Theodoric of Freiberg, Rabbi Levi ben Gershon, Johannes de Muris, and Paul of Taranto.

The Four Innovations That Made Modern Science 1. A notion of explanatory power on which all scientists agree 2. A distinction between public scientific argument and private scientific reasoning 3. A requirement of objectivity in scientific argument (as opposed to reasoning) 4. A requirement that scientific argument appeal only to the outcomes of empirical tests (and not to philosophical coherence, theoretical beauty, and so on)

Late in the seventeenth century, the philosophically unified machinery of inquiry in which the wheels and cogs rotate as one was spiked. Newton was the saboteur, and thus he was the chief architect of modern science’s first great innovation. Rather than deep philosophical understanding, Newton pursued shallow explanatory power, that is, the ability to derive correct descriptions of phenomena from a theory’s causal principles, regardless of their ultimate nature and indeed regardless of their very intelligibility.

Every reader, then, pours their own plausibility rankings onto the desiccated framework of a scientific article, bringing it to life and drawing conclusions accordingly—conclusions that are saturated with subjectivity and that consequently differ from scientist to scientist.

EUROPE, once Luther’s “Ninety-Five Theses” went out, was forever to be spiritually divided—the new Protestant versus the old Catholic faith; citizens, rulers, and territories of opposing religions living uneasily side by side. Violence followed soon enough: popular revolt in Germany in the 1520s; English dissidents burned at the stake in the 1550s; the desecration of churches in the Low Countries in the 1560s; full-scale war in France from then through the end of the century. It was to get worse. In 1618, the Protestant nobles of Bohemia, rightly fearing for their religious freedom, spurned their Catholic king Ferdinand—famously by ejecting his representatives from an upper-floor window of Hradčany Castle in Prague—and appointed a Calvinist prince in his place. The deposed Ferdinand soon after assumed the station of Holy Roman Emperor, thereby becoming the ruler of a motley but powerful confederacy of Central European states, some Catholic and some Protestant. He marched on Bohemia to take his revenge. These were the opening moves of the Thirty Years’ War, the conflict that launched Descartes’s short, uneventful military career and devastated Europe. Although the war began over a matter of religious toleration, it soon grew into far more than that: a war between the Bourbon dynasty that ruled France and the Habsburg dynasty that ruled Spain and the Holy Roman Empire; a war by which the German princes asserted their rights against the Holy Roman Emperor; a war of territoria...

The knowledge machine, in its contemporary realization, is highly effective at advancing human goods, but it is not a high expression of what is humanly good.

The bitter fate of humanist thought has been to see its glorification of the full, unifying intellectual potential of the human mind eclipsed by the immensely greater contribution to our knowledge of the natural world made by the lean scientific spirit—to comprehend the meagerness of what is found beyond the golden gate of the imagination when measured against the riches brought back through the low and shameful gate of experience.

When I suggest that science will better flourish if allowed to go its own way, then, Collins and Pinch might think that I have given a bad answer to the wrong question. What we should ask is: how can science be reined in? The archetypical golem was brought into being in the late 1500s by the leading rabbi of Prague, Judah Loew ben Bezalel, to protect the city’s Jewish population. According to one account, when it began to run amok, the rabbi had to take back the animating incantation—emet, the Hebrew word for truth—from the golem’s mouth. His creation turned to dust. In the legend, you might discern the radical subjectivist agenda: take away science’s claim to absolute truth and it will be tamed. A more careful reading of Collins and Pinch’s metaphor shows, however, that neutralization of the knowledge machine is very far from their aspirations. They take the golem to be a “bumbling giant,” a “creature of our art and our craft,” whom for all its faults “we should learn to love for what it is.” The aim of their book is not to bring science to heel, but to understand how it works, to see how its knowledge is made.

That is my project, too. I do not, as you know, endorse the understanding of science proposed by subjectivists such as Collins and Pinch. They have overlooked the iron rule; consequently, they have missed the scientific method. Restore the method to its proper place at the heart of the machine, however, and the image of the golem retains its force. The golem of legend was made of clay and brought to life by a magic word. The science golem’s raw material is people, organized and empowered by the iron rule. (It is bronze, not iron, but otherwise the sculptor Eduardo Paolozzi’s transmogrification of Blake’s Newton, shown in the frontispiece to this book, is an apt portrayal of a man made knowledge machine.) The golem of legend had a mind of its own. Science is made up of many minds—those of a multitude of scientists, each interpreting the evidence in the light of their own culture and education, their own taste and inclination, and acting accordingly. Yet at the center of this multiplicity sits something further, the public arena in which scientific debates unfold. That we can understand as a theater of consciousness belonging to the golem itself. The golem’s memory is the archive of observation and experiment; its trains of thought are the arguments published by disputing scientists. Such reasoning as goes on in the golem’s head is therefore incomplete and conflicted. But at the same time, it operates at a remove from the human concerns of the people of which it is made. Hav...