Eight—
The Meaning of the Mechanistic Age

Roger Hahan

The late Eduard J. Dijksterhis of Utrecht coined the term "Mechanization of the World Picture" to characterize the nature of the intellectual revolution that emerged triumphant in the seventeenth century. In his pathbreaking work, written close to forty years ago, he repeatedly refuses to provide a static definition for his central conception, choosing instead to describe it by showing how it emerged from a rediscovery and recombination of certain key strands of Greek natural philosophy in the late Renaissance and how it was centrally shaped by the success of Galileo and Kepler's new astronomy, Descartes's and Huygens's new philosophy of physics, and newton's grand synthesis at the end of the century.

Conceptions of the world picture since the seventeeth century have admittedly never been the same. The Aristotelian universe of essential qualities and goal-directed forms apparently was displaced by the new mechanistic philosophy. For the last forty years, that transformation, known to historians by the shorthand label of the Scientific Revolution, has been chronicled, its origins hve been established, and its character has been the subject of dozens of major monographs. Curiously enough, the issues Dijksterhuis broached but refused to settle have never been fully analyzed from a modern perspective. My concern is to offer some suggestions for finding a meaning for this Mechanistic Age which rests on historically sound grounds. That meaning requires special attention because "mechanistic" is the common epithet hurled at "reductionists." They are often crudely charged with a desire to eliminate the study of living beings by grounding them exclusively on the physical sciences. If we proceed with a historical analysis, we will see that the label "mechanistic" carries with it other substantial implications.

Perhaps the biggest obstacle to arriving at a full appreciation of the

notion is in fact for us to remain captive of too strict a chronologicla view. Historians of science—and I must include myself among the guilty ones—have, through their decades of refining the meaning and arguing about the temporal limits of the Scientific Revolution, locked themselves into a much too narrow identification of the Mechanistic Age with this movement. It behooves us first to clear away these constricting and ultimately misleading views of the Sicnetific Revolution to permit reaching for a more encompassing meaning.

The current notion of the Scientific Revolution, though it has a history that would take us back to the eighteenth century, is in fact the by-product of a set of lectures given at Cambridge in 1948 by the late Sir Herbert Butterfield, eventually published under the title, The Origins of Modern Science . That notion was successfully elaborated by a group of major scholars that includes the aforementioned Dijksterhuis and my teachers and colleagues Alexandre Koyré, Marie Boas, her husband, A. Rupert Hall, Paolo Casini, I. Bernard Cohen, Thomas Kuhn, and most recently, Richard S. Westfall. They and their followers all suffer from a common historic myopia, namely, the unitary identification of the momentous Revolution with the "Mechanical Philosophy" and the conviction that its culmination came in the person of Sir Isaac Newton, whose Philosophiae Naturalis Principia Mathematica is justly hailed. As a consequence of this shortsighted view, historians have too rigidly equated the Scientific Revolution with the advent of a Mechanistic Age and struggled to confine its development to the seventeenth century, principally in an English context appropriate to Sir Isaac.

An oversimplified view of their argument runs somewhat as follows. Following on the almost simulatneous discovery in 1609 by Kepler of the ellipticity of planetary orbits and by Galileo of the physical imperfections of celestial bodies like the Moon and Jupiter seen in his telescope, progressive natural philosophers were forced one by one to abandon Aristotelian and Ptolemaic dicta concerning the cosmos. In the next decades, the old order was shattered beyond repair by a flood of opinions that included a devastating critique of Peripatetic concepts about the closed universe structured around a central point and its attendant terrestrial physics based on the idea that motion was determined by essential qualities residing in substance. The separation of the cosmos into a world of heavenly perfection and earthly imperfection which mirrored Christian beliefs, and of the correspondence between the microcosm of man and the macrocosm of the universe, was recognized as obsolete and jettisoned as misleading. Critical philosophers like Bacon and Descartes ridiculed assumptions abou tthe erroneous grounds on which the older epistemology was based and began to proclaim a new philosophic order.

By the 1630s, its building blocks had been individually assembled: a

new philosophy o mathematical cogency, often coupled with experimental confirmation; the postulation of a corpuscular ontology that focused on quantifiable elements and mechanisms immediately apprehended by the eye and the mind; infinite, isotropic space that was indifferent to the nature of the objects placed in it and hence stripped of hierarchical values taken for granted by traditional religious authorities. By the end of the seventeenth century, so the official line runs, all these pieces were brilliantly assembled into the Newtonian system of the world with its universal laws of motion, its new metaphysic of inert matter, absolute space and time, and the proclamation of a new progressive epistemology of the mathematical and experimental natural philsophy. Moreover, it is pointed out, Newton found it possible to incorporate a modified set of Christian values about the Lord into his mechanical and corpuscular system so that it would continue to reflect the harmony and power of the deity in the cosmos. Sir Isaac returned the favor of his prophetic birth on Christmas Day, 1642, by lending his genius to the Almighty to "save" the cosmos for Christianity. You will surely recall Pope's famous couplet that expresses the blessings Western Civilization received when "Nature and nature's laws hid in night: / God said, let Newton be! and all was Light."

What is wrong with this interpretation from our perspective? It evades larger historic issues by giving a narrow, temporal, and geographic location to the Scientific Revolution, assuming it to coincide with the process of the mechanizationof the cosmos. Ideas as profound and important as mechanisms have both roots and consequences that cannot be confined to seventeenth-century England. In saying this, I do not advocate the fashioning of a counterthesis, merely the decoupling of the concepts. Today aswell as in the seventeenth century, in the world of Western civilization, whether it is found in Israel, Japan, or Merry Old England, we mainly operate with the assumptions of the Mechanistic Age. let me elaborate.

The notion of the mechanical involves quite a few dimensions that, for the sake of analysis, I would like to display singly, keeping in mind that they are hisotirclaly and conceptually interlinked.

First is the machine itself, with its internal workings displayed for all to apprehend. While it was principally articulated after the invention and with the help of printing, the machine was no newcomer to the Renaissance. Every civilization fashions more or less elaborate tools to cope with nature, but few had given them such a special place as did the Hellenistic Greeks and their Roman followers. Engines of war and construction were at first merely described with words and their principles laid down using terminology common to natural philosophers by major figures like Archimedes. Already in the third century B.C., it ws aximomatic that their functioning was based on a geometric undersanding of physical princi-

ples, in which number, proportion, size, and configuration were critical and for which the strength of materials and thermal forces responsible for expansion nd contraction provided an essential explanatory component. Simple laws of leverage and the schemes for multiplying mechanical advantages by the use of the wedge, pulleys, and gears were well understood by engineers like Philo of Byzantium and Hero of Alexandria who used them to make sense of the common machines of antiquity.

But the Greeks also developed mechanical principles to serve quite different ends. They fashioned automata, that is, self-moving objects dressed up to resemble and imiate the operations generally ascribed to willful agents. One finds described singing birds activated by water pressure, temple doors that open in response to the lighting of fires, puppet shows representating shipyard workers, and mixing vessels that seem to be filled mysteriously as they are visibly being emptied. Such elaborate toys, popular in the Byzantine world, built to astound the spectator rather than enlighten him, are a testimony of the genius of ancient crafsmen.^[1] But they also testify to the ancients' use of machines to glorify their own ability to penetrate nature's secrets and to mystify the gullible public by the fashioning of mirabilia . They are part of an ancient and tenacious thaumaturgic tradition. All themechanisms to produce these effects are carefully hidden from view so as to increase the sense of the marvelous.

In ancient times, such automata were not built as mechanical models to explain living beings; they existed merely to imitate nature they way that an ancient artist would strive to copy and reproduce natural occurrences. A measure of the prowess of the artisan was his ability to reproduce in the most faithful way possible the natural processes we experience. Prior to the advent of Christianity, nature was worshiped because it encompassed such wonders; man's accomplishments would be measured by his ability to mimic life, not to make it serve his secular purposes. In the rare instances we know about the Greek mechanist was proud to have outdone nature by feats of trickery, often executed by use of mirrors, by which the right and left might be transposed from their natural order or by which small objects might be magnified by placing them under a distorting glass object.

What differentiates this use of the mechanical artifact from the post-Ranaissance version is the emphasis on secret processes, the reveling in the mysterious ways of nature. Mysterious at least to the public! The treatises from which we garner this picture of the Greek notion of machine were meant for the engineers, the few in society adept at understanding and imitating the cosmos. The mechanicians of ancient times were in this sense askin to the alchemists: by the use of secret means, the alchemist had meant to reproduce in the laboratory the complex procedures found in nature to grow metals in the telluric womb. The alchemi-

cal mahatma was the one who could imitate nature and perhaps speed up its natural processes. Man might coax nature along, but he never meant to dominate it.

The picture changes markedly as these ancient treatises are rediscovered and edited in the renaissance, Hero, for example, in 1575. The spellbinding character of the mechanical contrivances is embraced by enthusiastis like Della Porta as part of the magical tradition, known to contemporaries as the secrets of nature. Knowledge about them was shared among the adept as an initiation rite for entrance into his Neapolitan Accademia Secretorum Naturae . But alongside the older approach to machines, a new tradition had already found favor with the other, more practically minded aritsans. Agricola, for example, despite his humanistic training, focused on the actual descriptin of machines employed by miners in his De Re Metallica (1556). Like his contemporaries, Biringuccio and Ercker, he took his mission to be to assemble a handbook of mining based directly on practices he observed in Saxon mines, and he strove to make them immediately accessible, though in the language of Columella and in the accompanying illustrations. He was not alone in this genre. Indeed, so many texts describing the arts of sailing, cartography, architecture, fortifications, gunnery, hydraulics, bridge building, and so on, often presented in the vernacular and accompanied by numerous diagrams, were published in the late sixteenth century that they provoked the compilation of encyclopedic treatises that became an immediate printing success. Jacques Besson's Theatre des instrumens mathematiques et mechaniques (1578), Agostino Ramelli's Le Diverse e artificiose machine (1588), and Vittorio Zonca's Novo teatro di machine et edificii (1607) all have in common the exaltation of machines as human inventions, downplaying the notion of artisans as mere imitators of nature. These compilers share the goal of spreading new knowledge to the multitudes. Evne the illiterate artisans were permitted to profit from them, merely by studying the sumptuous illustrations.

Machines were now directly linked to the expectation of progress through mechanical improvement, a phenomenon that was widespread in the increasingly commercial and urbanized society of early modern Europe.^[2] The same mood has continued unabated to our present day and is the most important root of the Mechanistic Age in which we operate.

What was gained through this dimension for the making of the Mechanistic Age is not just publicity and progress and its concomitants, democratization and the material improvement of society. The visual representation of machines forever stripped them of secret recesses and hidden forces.^[3] The learned reader now expected to see for himself how things worked, no longer depending solely on classicla authorities for confirma-

tion. In his preface to De Re Metallica , Agricola assures us he personally went into the mine itself. In 1600, William Gilbert similarly dedicated his De Magnete: "to you alone, true philosophizers, honest men, who seek knowledge not from books only but from things themselves."^[4]

The new style of philosophizing, preferring things to books and concrete, visually reliable instances to rhetorical systems of thought, was of course at one with the new experimental philosophy embraced by Galileo, Bacon, and even, to some extent, Descartes. Galileo sets the debates between his interlocutors in his Discorsi in the Venetian Arsenal where deeds speak louder than words. In a clear sense, the theoreticians of the Scientific Revolution borrowed a frame of mind from the artisan traditions displayed in the "theatre of machines" literature. Scientists' new preference for the palpable is evident not only in their prefaces but in their defense of demonstrations and experiments as the new arbiter among competing theories. It is no accident that all of the important discussion groups of the seventeenth century, from Gresham College to the Berlin Academy, owned scientific equipment and hired demonstrators. The tone of the new sciences was to displace the occult by the visible, the mysterious by the palpable.

Here once comes to the second important way by which we may analyze the meanings of the Mechanistic Age. It is characteristics of philosophical discussions of the era to reject occult forces whenever possible and to substitute for them self-evident principles much like one sees when watching a simple machine in operation.

According to the new mechanical philosophers, Aristotelian reliance on essential qualities as the central explanatory device in physics was the major weakness blocking the growth of understanding. To explain change by referring to an immaterial form that "informs" matter was quite unproductive. The charge was advanced, for example, that asserting an object falls to the center of the universe because its essence is heaviness is as illuminating as Molière's medical student who explains the powr of opium to put patients to sleep as the result o a virtus dormitiva (opium is a soporific because it contains a dormitive power).^[5] Peripatetic strategy seemed to obfuscate by substituting words for real causes. When asked further why earthy matter was heavy or opium soporific, the answer invariably was circular: because it was "in the nature" of the object to act in this fashion. How could progress ensue when playing such a dead-end rhetorical game?

Historians of the Scientific Revolution customarily claim that the introduction of the mechanical philosophy broke this impasse by providing a solution to this philosophic dilemma. If visible, palpable mechanisms of change were substituted for the hidden, occult forms, the future of natural philsophy might be ensured. And none seemed more intelligi-

ble than ction through direct contact. The immediacy of understanding that comes from watching a stationary billiard ball move when struck by another, or how power is transmitted from one gear to another, or even how blood gushes from an opened artery when the heart contracts had a dramatic impact on the mind confused by Peripatetic verbosity. Even the seemingly complicated functions of animate beings were rendered more understandable by assumptions that their members—the hand or arm, for instance—operated as did machines, with levers, gears, pulleys, and gates, following the commands of the mind.^[6] In the late seventeenth and early eighteenth centuries, bodily parts were pictured as individual mechanisms. The structural correspondence between man-made manchines and living entities was adopted because it promised a new degree of intelligibility. The new scientists of the seventeenth century could readily give up on the old metaphysics when they juxtaposed the mechanical world of their era with the scholastic auditorium in universities, one vital, illuminating, and progressive, the other stultifying, fruitless, and tautological.

What principles did they propose instead? The new rule adopted was to ground all explanations on the idea of matter in motion. The corpuscular philosopher, who unashamedly borrowed from ancient atomists, found new psychological satisfaction in reducing the complexity of nature to the simplicity of corpuscles capable of motion and causing change by impact only. To the mind troubled by the old verbiage, they were surely preferable to Peripatetic forms and qualities. For Descartes, the principal systematic proponent of this view, matter was the analogue of extension, in the same way space was defined by the objects that occupied it. Common sense as well as logic showed us with undeniable reality that things are composed of matter and that next to impenetrability, matter was principally characterized by its location. Motion, too, was grounded on irrefutable visible existence. Neither was hidden or occult. Both were, as Descartes enjoyed repeating, clear and distinct and, to his mind, ultimately real. The mechanical philosopher reveled in having found an ontologiclaly satisfying basis for apprehending nature, one that was not merely true by virtue of what the senses and the mind perceived but that could also be manipulated by mathematical symbols rather than scholastic terminology. Adopting the mechanical philosophy brought in its wake the ascendancy of mathematical language that purportedly guaranteed that proper logic would be observed and clarity maintained. It seemed to answer all the criticism laid at the door of the ancients and to offer a hope for depening our understanding.

To a considerable extent, the mechanical philosophy provided a much-desired new ideology that brought success to many seventeenth-century natural philosophers. It had all kinds of advantages. For Des-

cartes, as it had for Galileo earlier and was to have later for Locke, it permitted the separation of primary from secondary causes into the fundamental quantitative and the derivative qualitative realm. As a well-taught paradigm, it served to focus generations of scientists on specific riddles of nature—for example, the nature of the vacuum, the production of colors—that required experimental elucidation. But it would be a gross historical simplification to suppose that this new philosophy solved all the old problems and earned Descartes universal accolaim.

Practitioners of the new philosophy realized all too quickly that Descartes had substituted a new ontology for the old one—the quantifiable for the qualitative—but it was itself metaphysical. Instead of relying directly on tangible experience, it proposed principles, different from those of Aristotle but principles nonetheless. Scholastic debate was by no means absent from discussion centers where Descartes's philosophy was taught and applied. Was extension coterminous with matter? How divisible were corpuscles, and how many kinds of matter were there? How was movement transmitted and its total quantity in the universe to be measured? How could one verify by palpable, visual experiments the submicroscopic explanations for the action of the lodestone, or the production of colors? Leaving aside for a moment the immense problems posed by living matter for Descartes, how could one fully understand the motion of the heavenly bodies in elliptical paths? The new mechanical philosophy seemed to have created as many new problems as it resolved. Some of the solutions offered clearly reintroduced into our language the very occult terms that Descartes and his followers had thought to have repudiated. A major group of thinkers, particularly in England and including Sir Isaac, sought the answer to the mechanical philosopher's weak points in the nature of the deity, or by postulating universal gravitation and short-range affinities of an electric, magnetic, or even alchemical sort. It is particularly because of this historic turn of events that I urge a decoupling of that which has led us too casually to equate the Mechanistic Age with the Scientific Revolution. By following the intellectual path chosen by Newton too exclusively, as most of my colleagues have done, they have made us lose sight of the continuing agenda of those who instituted the Mechanistic Age.

A third and very subtle aspect of the Mechanistic Age was the change in emphasis traditionally give to the notion of causality from what Aristotle called formal and final causes to efficient and material ones. Indeed, many who embarked on this path found themselves holding a nominalist position that went so far as to deny causality altogether—witness David Hume's mid-eighteenth-century critique. The detailed history of this change has yet to be written, but its main stages within the history of science are clearly evident and provide a major ground for later criticism

of the mechanistic philosophy.^[7] By diminishing the importance of first causes, or even denying the possibility of reaching them, the mechanistic scientist has abandoned a task natural philosophers originally assumed for themselves: to make complete sense out of the world and to provide an explanation for it by attributing a goal for nature and its creator. The Mechanistic Age completed the process of displacing teleology in favor of a search for laws that link phenomena in regular, repeatable patterns of behavior. Note that the historical trajectory that takes us from Plato to the positivists of the nineteenth century passes through the Scientific Revolution but is not restricted by it. Conversely, all the actors of the Scientific Revolution were not equally committed to the abandonment of final causes. Moreover, leaving out Hume, the main proponents of this constituent lived on the Continent and operated next to the mainstream of the traditional Scientific Revolution: Pascal, Malebranche, d'Alembert, Buffon, Laplace, Bernard, and Du Bois-Reymond. There is insufficient space to carefully map this path, so I will confine myself to illustrating it mainly with Laplace, for it was in his hands that this aspect of the Mechanistic Age found its most assertive and pregnant outcome, the principle of strict mechanical determinism.

As is well known, both Plato and Aristotle drew on telos as the central concept for explaining the world. Not only were structures of living beings best understood through their function but all physical change was expressed in terms of a process analogous to substances fulfilling their natural destiny. Aristotle had specifically singled out the atomists for criticisms because their system left events to chance. For him, all satisfactory explanations required an overdetermined set of causes that left no room for fortune. When atomist notions were refurbished in the seventeenth century and were adopted for the establishment of a cogent mechanical philosophy, the charge of impiety was added to the discomfort evidenced over the belief that all could ultimately be made intelligible by the fortuitous interplay of invisible material elements. But there were devout Christians like Pascal and Malebranche who took refuge in the idea that even though the natural philosopher could never divine the real intentions of God, he could at least note nature's regularities and establish the phenomenal laws under which they operated. Like other nominalists, they radically separated God's omniscience from man's limited abilities to reach essences and to fathom purposes.

It is no accident that such developments took root precisely at the time when the scientific community began to organize and define itself against the older natural philosophic tradition. Not only did scientists of the second half of the seventeenth century develop communication networks and produce works collectively sanctioned but they also sought out a rationale for a separate existence which offered them a differential role in

the world of intellectuals. In effect, scientists like pascal and Malebranche acknowledged the existence of a sphere of activity in which scientists had little to contribute, namely, theology, but proclaimed the special ability of colleagues to study nature directly and extract from it ever more precise regularities.

Those familiar with the English tradition in natural religion, in which Sir Isaac Newton participated, will notice what a radical turn this Continental path represents, a point that once more underscores my admonition to stray from the straight and narrow path mapped out by traditional historians of the Scientific Revolution.

Yet in another important sense, the followers of this Continental path shared with their colleagues across the Channel a distruct of essential qualities. At about the same time, but on different occasions, d'Alembert and Buffon, who were each accused of anti-Christian leanings, were annoyed by the continued fascination their contemporaries displayed for claiming to apprehend nature's true being. Buffon argued for an empirical system of natural classification to describe the realm of natural history; d'Alembert argued for a redefinition of the elusive concept of what we now call energy conservation, to avoid having to ground his physics on an essentialist understanding of gravitational forces. Both of them justified their stand by narrowing the territory in which scientists with their current methods could reasonably expect to make headway. Although religious authorities failed to interpret it this way, nominalist scientists retreated from the impenetrable domain of final causes, cheerfully turning it over to the ecclesiastic community, while asserting their authority to speak about the empirically based laws of nature with self-assurance. That position is still fashionable today and continues to constitute a major argument in defense of science's autonomous right to know regardless of its consequences in other domains of culture.

Laplace's major contribution to this component of the Mechanistic Age was to demonstrate with heavy scientific artillery in probability theory, celestial mechanics, and physics that such a specialized, professional approach, far from diminishing the extent and richness of the scientist's domain, helped him focus on what it was reasonable for man to understand and to dream constructively about what might be possible. He did this on several occasions.

In a classic paper on heat written with Lavoisier in 1783, he argued that the ultimate truth of competing theories about its nature (kinetic vs. materialist) was best set aside in favor of the establishment, with careful experiments, of the behavior of thermal phenomena.^[8] To that end, Laplace invented the ice calorimeter to measure heat exchanges in combustion and respiration and derived tables pointing to laws for the expansion of metals on heating. For us, it matters little that his efforts were

easily bested by the next generation of physicists. What is noteworthy, considering his great authority in the scientific community, was his explicit disregard for quiddity as long as some progress could be achieved by empirical means. Laplace laid great store in what we call an operational or instrumentalist view of science, one that favors the knowlable mechanisms of nature, studied mathematically, over its deeper and less evident aspects. He preferred the palpable to the speculative. In discussing respiration, for example, Laplace and Lavoisier confined themselves to statements about the oxygen consumed and the heat produced, leaving aside all reflections on the relationship between the nature of life and vital heat, a commonplace subject in their epoch.^[9]

We legitimately ask if this conscious choice was merely a stratagem to disarm nettlesome religious or philosophic critics or a conviction about the speical nature of the scientists' occupation.^[10] Undoubtedly both. Beyond this, and for personal reasons, Laplace also preferred epistemological certainty to ontological profundity. In one of those paradoxical events that befalls so many in their lieftime, his conventional career choice of the priesthood had been shattered by a conversion experience brought about by the discovery of the beauty and power of the analytic versions of Newtonian astronomy practiced in France. Laplace, moreover, fashioned a new mathematical tool, the a posteriori calculus of probabilities (statistical inference) that he assumed would lead with ineluctable power from observed phenomena to laws of nature and from laws to causes. The most remarkable by-product of his efforts was his massive fivevolume Traité de Mécanique Céleste , which offered a thorough analysis of the Newtonian astronomical world, using the new language of calculus but entirely stripped bare of the theological and metaphysical concerns Newton prized so dearly.

Like Newton, Laplace shunned unfounded hypotheses. A particularly clear instance of his reluctance to accept speculative theory when no direct evidence was available was his reaction to a clever but bizarre hypothesis proposed by the Genevan Le Sage to explain universal gravitation.^[11] This completely mechanistic theory involved numerous tiny ultramundance particles traveling at great speed through space in a random fashion. In this model, attraction was the result of the mutual shielding efect solid bodies would have when in proximity to each other, an effect that would increase greatly as the distance between them decreased. Laplace demanded to know what speeds and masses the hypothesis entialed. When they turned out to be larger than the speed of light, he lost interest. Le Sage's particles were a clever but vacuous jypothesis that could not be tested directly with apparatus at hand and hence were not worthy of the concern of a practicing mechanistic scientist. The Mechanistic Age demanded tanglible evidence rather than un-

supported models, even when these truned out to be based on the principles of matter in motion.

It must not be assumed from this that such a positivist stance, which favored fact over fancy, ruled out hypotheses, or altogether blocked their use. It merely distinguished between pure conjecture and imaginative solutions that were testable. Laplace's postulation of the nebular hypothesis to account for the origins of the solar system is an apt illustration of this. Using probability theory, he argued that there must be a physical cause responsible for the planet's orbiting around the sun in a place close to the ecliptic, all in the same direction and with nearly circular paths. His hypothesis, though thoroughly speculative, was nonetheless testable and fruitful, hence acceptable until it was refuted. Clearly, the philosophy of what we might call phenomenological positivism did not constitute an obstacle to the scientist's imagination. On the contrary, none is more visionary than Laplace's mechanistic assertion of determinism:

The present state of the system of nature is evidently a result of what it was in the preceding instant, and if we conceive of an Intelligence who, for a given moment, embraces all the relations of being in this Universe, It will able be able to determine for any instant of the past and future their respective positions, motions, and generally their affections.

Physical astronomy, that subject of all our understanding most worthy of the human mind, offers us an idea, albeit imperfect, of what such an Intelligence would be. The simplicity of the laws by which celestial bodies move, the relationship of their masses and their distances allow us to follow their motions through analysis, up to a certain point: and in order to determine the state of the system of these large bodies in past or future centuries, it is enough for the mathematician that observation provide him with their position and speeds at any given instant.

Man owes this advantage to the power of the instrument he uses and to the small number of relations he employs in his calculations; but ignorance of the diverse causes that produce the events and their complexity, taken together with the imperfection of analysis, prevent him from making assertions with the same certitude on most phenomena.^[12]

It is clear from this remarkable credo that Laplace expected future progress in science to depend on a patient but correct adaptation of the methods of astronomy to the unsolved problems of nature in other realms. On different occasions, he expressed this vision specificially for crystallography, chemistry, and psychology. In an unpublished manuscript, he repeated this conviction for biology. But we would be mistaken if we assumed his philosophy of astronomy depended on the adoption of specific axioms about matter—for example, that it be inert rather than self-activating—any more than if we assumed he refused to consider alternate theories of heat and light to the corpuscular ones favored in his day.

For him, as for many of the biological reductionists of the nineteenth century, it was the proper scientific approach to problem solving that counted more than the specific character of the theory employed. The epistemological virtue of the "mechanistic" approach mattered more than its materialistic ontology.

The physiologist Magendie, who was Laplace's desciple, and his famous student Claude Bernard accepted the notion that living beings could not transgress the laws of the inorganic world but maintained they were additionally held to laws of the organic realm.^[13] Du Bois-Reymond, who belonged to the group that signed a reductionist manifesto in 1846, also adhered to this notion and recommended that only physical and chemical tools be employed to analyze physiological phenomena. He did so principally because their operations were intelligible, not because physics and chemistry were ontologically more reliable or prior.

It seems to me a major historical misunderstanding to argue that the philosophy of biological reductionism turned on a temperamental philosophic preference for the physical over the life sciences. The record, as it is now being unfolded by historians of the nineteenth century, shows that it was the example provided by the physical sciences more than their principles that impressed researchers in biology.^[14] Most of the great figures received training and developed their ideal picture of what a solid science might be from experience with astronomy, physics, and chemistry. In one way or another, they all took to heart messages like the one offered by Laplace that, with sufficient persistence, the life sciences would soon arrive at a stage of maturity that gave them the kind of power of penetration reached by followers of Newtonian astronomy. We now know that their optimism was perhaps a bit premature. In their enthusiasm, they may have failed to count on the almost limitless variety that exists in the natural world and the complexity of living processes. Yet the faith in progress through the adoption of experimental science is still the driving force behind today's research programs. In that sense, the effects of the Mechanistic Age are still with us.

Ultimately, the critical by-product of the Mechanistic Age was to have provided examples of how nature could be apprehended by men of science. to be acceptable, as we have seen, any new science had to reveal the mechanism of its theories to the eye, to be grounded on verifiable evidence, to adopt an unambiguous vocabulary for the sake of clarity, to aruge cogently (preferably employing a logically reliable language), and to concern itself with immediate rather than distant causes, in any case, causes that could be tested. In short, the Mechanistic Age offered a philosophy for scientific understanding that had proven to be effective and remarkably productive.

There are other features that our rapid historic survey may have

enabled us to have glimpsed, though they are more implied than made manifest. It is perhaps most evident in the Laplacean credo. Whereas in ancient times, man and the universe were considered first as the byproducts of a creator to be contemplated and imitated, since at least the nineteenth century, the scientifically informed mind has been prepared to substitute his mental prowess for that of God. Laplace's Intelligence could just as easily be a perfected human calculator as the Supreme Being. Thus it is that the modern scientist is potentially in as good a position to construct the universe and manipulate it according to his cumulative insights as he is to analyze a universe created by a deity. In the modern era, understanding has become a means of control. Man is now the mechanic, the maker of the machine: What Vico implied by asserting the identity of verum and factum , what man makes, he is able to know.^[15]

The Laplacean credo of determinism not only offered the potential of prediction, and hence a measure of control, but it also promoted man to the rank of a lesser god. That message was well understood by many of the biological reductionists who were uneasy with its implications. Du Bois-Reymond was the most explicit spokesman who raised doubts about the ultimate power of the scientific mind. In a series of popular addresses on science over a century ago, he explicitly set limits to the power of science, maintaining that despite the likelihood further research would dissolve some of our ignorance, there were issued that would never be settled by science.^[16] He listed seven impenetrable riddles of nature that would forever remain byeond our ken. What is significant about them is that they included issues dear to physical scientists as well as his bilogical colleagues. They are not canonical enigmas, but his list nonetheless illustrates the kinds of metascientific issues he considered beyond the limits of the wisdom of scientists: the essence of force and matter; the origin of movement; the origin of life; the purposeful character of nature; the nature of simple sensations; the origins of intelligence and language; and the riddle of freedom of the will.

Despite the remarkable progress of science, the nineteenth century was also the period in which doubts about the implications of the Laplacean credo emerged. It is a measure of the ambiguity with which his message was greeted that Du Bois-Reymond reminded his listeners that man was not omniscient. Perhaps he should also have reminded us that he is not omnipotent either. I have always been impressed that Goethe's Faust and Shelley's Frankenstein appear on the historic scene just as the Mechanistic Age is in its full glory. Does this not suggest that issues of this magnitude are never settled?

As stated at the outset, the modern age was nonetheless irretrievably transformed by the establishment of a philosophy of mechanism that showed how much understanding could be enlarged by adopting its

tenets. True, modern man could not expect to equal the prowess of the deity simply by the use of his new secular instrument, but he could now hope to deepen his grasp on nature with considerably more confidence.