From: JASA 19 (September 1967): 115-119.
Did mechanistic philosophers in the seventeenth century actually believe that the world was mechanistic throughout, or did they merely deem it methodologically wise to proceed as if such were the case? At many points they explicitly avowed the methodological position; they did so as part of their reaction against scholasticism, according to which absolute certainty was possible. Seventeenth century savants felt that man could not know the inner nature of the world with certainty. They placed a more modest limit on human abilities, claiming that at best we could merely describe the appearances, we could not penetrate with certainty to the heart of things. But at many junctures they did not heed their own caveat. Their mechanism, which is announced as methodology, actually is more than that, and constitutes a metaphysical contention.
contention of the book was that light, of all things, was nothing other than
an effect of matter in motion. Huygens wrote at the end of the seventeenth
century, when mechanics was busy assimilating almost the whole of science.
Before mechanical philosophers were done, they spoke of the universe as one
great piece of clockwork, and of God as an artificer. Did the mechanical
philosophers really believe the world was mechanical, or did they instead find
it scientifically useful simply to proceed as if that were the case?
*Peter A. Pav is in the Division of Humanities of Florida Presbyterian College, St. Petersburg, Florida.
was their mechanism a methodological position or a metaphysical one? Did
mechanists actually believe the world was mechanical, or did they merely proceed
as if such were the case? That is the question. Its answer is best
prefaced by a consideration of the birth, growth, and nature of the mechanical
Such intellectual movements as the scientific revolution usually take their greatest stimulus from a reaction to preceding views. In the present instance, the idol to be tumbled was scholastic Aristotelianism. In the eyes of the founding fathers of modern science, Aristotelian explanations were not just false. They were wrong-headed, because they were occult, outmoded, and mystic, little more than mere verbiage. Moli6re, in an oft-quoted passage from Le malade imaginaire, uses the medical qualifying examination of Bachlierus to mimic scholastic science. Bachlierus is asked for the scientific explanation of why opium induces sleep.
I am asked by the learned doctors to give the cause and reason why opium produces sleep: To which I respond, because there is a dormitive virtue in it, of which it is the nature to still the senses.The doctors reply in chorus.
Well said, well said, well said, well said. Worthy, wortby to enter into our learned body.2Moliere's overstatement of the case is not entirely hyperbolic. His attitude was shared extensively; his account is a stereotype of others to be found extensively throughout the literature.
Did the scholastics say that gold is as it is because it has the forms of yellowness, density, malleability, and ponderability? Ridiculous. Here is how Robert Boyle put it:
If you ask a vulgar philosopher the cause of the fire burning, he will presently answer you, that the fire burns by the quality of heat that is most eminent in it: but if you further ask him what that heat is, and how it enables the fire to perform the various effects we daily see produced by fire; he will if he be ingenuous, confess to you in plain terms that he cannot tell, and though he be not, he will but in a confused and unintelligible discourse give you cause to conclude as much.3
Such a view of their predecessors was quite typical of seventeenth and eighteenth century natural philosophers. William Molyneux's dedication to the Royal Society of his Dioptrica Nova, in 1690, provides one more of many possible examples.
'Tis wonderful to consider, how the Schools were formerly overrun with a senseless kind of jargon, which they call'd Philosophy; and which men studied with the greatest Labour and Assiduity, that they might attain the name of Wise and Learned . . . and when they had intangled themselves in a thousand ridiculous Disputes about empty Questions, they vainly thought they had attained the Perfection of Philosophers; whilst they had no Ideas in their Minds answerable to those Noises they made with their Tongues; ... in this last Age the . . . Philosophick Societies of Europe . . . have dissipated these dark Mists, and have abdicated this kind of empty Stuff; which had crept into even Natural Disquisitions; and like a Leprosie had quite overrun the whole Body of Philosophy, deforming its Beauty, and ruining its Strength. Men are not satisfied now with noisy Words, and nothing else; but require more solid Foundations of Knowledge, and believe no farther than they can find good proofs . . . The Commentators on Aristotle . . . have rendered Physicks an heap of froathy Disputes, managing the whole Knowledge . . . by Hypothetical Conjectures, confirm'd by plausible Arguments of Wit and Rhetorick, ordered in a Syllogistical. form; and answering Objections in like manner: But never studied to prove their Opinions by Experiments. By which Method they were as ignorant of the Properties and Affections of Natural Bodies, as if they were not at all the Subject of their Disquisitions. . . . They'd tell you the Tides depend on the Influence of the Moon; and when you proceed farther, and ask, what is this Influence? They'll yet give you a Word for it, and say, 'tis an occult Quality: If you inquire, what an occult Quality is? They'r at a Stand, and having no farther hard Word here to fly to, are forced to confess 'tis a Quality they know nothing of. Had they not better at first have plainly confest, they know not the Cause of the Tides? no surely; For tho this had been more becoming modest Philosophers, it would not so well captivate the Vulgar, and gain to themselves the Repute of deep Knowledge.4
Recent scholarship has dealt more kindly with the scholastics than did Moliere, Boyle, or Molyneux. Nonetheless, such medieval concepts as essence, form, quality, and sympathy were indeed being displaced in the seventeenth century by space, time, and mass. Why did the seventeenth century refuse to discuss acids, for example, in terms of the substantial form of acidity, and refuse to regard chemical reactions as the process of actualization of a dormant potentiality? Would that have been any worse than talking in terms of unobserved, perhaps unobservable, atoms? What of the seventeenth-century explanation of acidic properties *in terms of sharp, pointy molecules, or tiny ones which moved with penetrating swiftness? Wedge-shaped atoms would give rise to a strong taste, for example, by sticking in one's tongue like so many little barbs. Yet such an explanation still begged the question, though perhaps not as obviously as the dormitive virtue did. After all, could not the explanation have proceeded as well in terms of massive, blunt particles which assaulted the tongue by brute force? And furthermore, what necessary relation is there between a sensation of taste, and the manner in which the tongue is accosted by atoms? It would seem just as reasonable to say that the actual acid imparted its form or quality of acidity to the tongue, giving a sharp sensation insofar as the tongue went from potentiality to actuality in respect of the quality of acidity.
Many of the 'new' scientific explanations look as if they were made from the old ones by the scissor-and-paste method of simply switching new terms for old, without further change. Surely, seventeenth-century scientists were not proud of something as trivial as merely exchanging one set of terms for another, mechanical for scholastic. They were happy because they had done a good deal more than just that. They had identified the logic of unobservables with that of observables; it was precisely at this point that their predecessors failed.
Once the medieval explanation had been given in terms of natures, forms, or qualities, further requests for secondary explanations of the concepts occurring in primary ones were not merely beside the point, but ludicrous. The heaviness of gold came from its inherent substantial form of ponderability. The explanans was more simple than the explanandum in being more irreducible; that is, at the end of the conceptual line. But it was not more simple in the sense of being more verifiable or easily known. It explained only the data by which it was generated, and that is barely explanation at all. The explanation of acidic hehavior pointed merely at the quality of acidity, which obeyed the logic of forms. That logic had precisely the characteristics needed to explain what had to be explained, and for an obvious reason-they were built in, ad hoe. This was what the seventeenth century meant when they hurled the accusation of word-juggling at their predecessors. But were the accusers themselves immune, since they had recourse to unobserved atoms? To some extent they were; for in replacing the forms and qualities by atoms in motion, they brought a powerful set of explanatory principles to bear on the matter at hand, one which had its logic already developed and tested; for a primary tenet of seventeenth-century atomism was that the atoms obeyed exactly the same laws as did macroscopic objects, the laws of mechanics which were proving their worth in explaining and relating all sorts of phenomena, from motion in the heavens down to the functions of the human body itself.
For the medieval scientist, the forms in iron of malleability, fusibility, and magnetism were completely independent; but in the seventeenth century they all were inter-related by their common cause, atoms in motion, in motion governed by known laws which reached through the whole of nature. The particulate structure of iron explained all of its observed properties, related them, and brought them all under the aegis of the science of mechanics. For example, the atoms composing iron were large, packed closely together, and sluggish, thus explaining its weight and solidity. Heat was merely atomic commotion, and if the atoms in a chunk of iron were sufficiently agitated by heat to break apart, the sample would melt, losing its shape, and also its magnetism, which depends on atomic alignment. It was in such a manner that color, taste, opacity, and all the other properties of iron would be explained in terms of atoms and their mechanical attributes. In actual fact, such a reduction was not effected until some two centuries later, in the nineteenth century. But even if the goal was not reached in the seventeenth century, it was clearly defined then. That was a remarkable accomplishment in itself.
The approach was, however, not without its excesses. An example is Descartes' explanation of magnetism in terms of spiral effluvia. Little corkscrews were emitted from ferro-magnetic substances upon magnetization. Should they meet any iron as they coursed through the air, they would burrow into it like a driven screw, pulling it forward and also magnetizing it. A freely suspended magnet would be aligned in space by their passage, since their right-hand threads could fit only one way, much like a bolt in a nut. Now, all this is indeed strained, but in an elliptic sort of way it is not quite as ridiculous as might seem. We today talk in terms of little domains of atoms lining up under the influence of a directional magnetic field. In fact, our explanation is all the more tenuous because of its dependence on diaphanous fields, and our atoms, in distinction to those of the seventeenth century, are quite different from anything we can see or feel. The saving point is that our explanation subsumes the behavior of magnets under a well-developed electromagnetic theory. What that theory is for us today, mechanics was for the seventeenth century, especially against the background of what had gone before. Mechanical philosophers were not engaging in fantasy, nor were they revolting for the sake of revolt. They were eagerly using what looked for good reasons like the best tool, mechanics. Science benefitted greatly. A mechanistic approach is perhaps not the only one which could have done the trick so nicely, but it is indeed one which did.
Besides effecting a unification, the mechanical philosophy had another important characteristic. The final explanatory terms-atomic size, shape, position, and motion-were all mathematically tractable; not only did all sorts of previously disparate properties become inter-related, but they were all related to the triumphal victor, mathematical science. No wonder men were so happy, for they had in their grasp the means of explaining an infinity of observable phenomena in the simple terms of a few properties of atoms, properties which were quite like those already known at the macroscopic level, and which were subject to a rigorous and fruitful calculus. What did it matter, then, if hardly any of the details were ever worked out? The general notion in itself was enough to carry the day.
It is appropriate now to come full circle back to the question posed at the outset, "Did mechanists actually believe the world was mechanical, or was it merely wise to proceed as if such were the case?" Was their mechanism methodology or metaphysics?
There can be little doubt that mechanical philosophers did treat nature as if it were mechanistic. Robert Boyle was but one of many who went so far as to liken the universe to the great and intricate cathedral clock at Strasbourg. However complex the world machine might be, the mechanists felt it could be understood by those who took the trouble to study. The world was not basically mysterious and unknowable.
Something could be learned in taking it apart and putting it back together; that is, in experimenting. The acceleration of scientific progress in the seventeenth century was directly related to the increased emphasis placed on experimentation. All this does not say that mechanism was merely a pragmatic approach and nothing more. But there are some explicit indications that the approach was only an approach. They can be found in Descartes, and are typical of mechanical philosophers in general; Descartes was speaking for his age.
When Descartes proffered his humorous explanation of magnetism, surely he did not mean that the world was really that way at all. He hardly could have expected readers to take him literally, but merely felt that he could aid the understanding of magnetism by proceeding in metapboric manner. His model encompassed the directionality of magnetic phenomena, their diminution with increasing distance, and several other aspects of magnetism. just because the model worked well, there was no need to claim that little screws actually were flying around. It might be useful so to proceed in investigating and explaining magnetic phenomena, but prudence would preclude mistaking the model for nature; that is, the portrait for the sitter.
In reading Descartes, another topic fosters the suspicion that mechanism was being used only as a tool. It concerns his efforts to give a purely mechanical explanation of the phenomena of light. He wrote that
light is . . . nothing else, in the bodies termed luminous, than a certain movement or a very prompt and intense action which passes to our eyes through the air and other transparent bodies in the same manner that the movement or the resistance of the bodies encountered by the blind man passes to his hand by means of his stick.5
Various colors and intensities of light correspond to different kinds of pushes on the stick. The model clearly supports the rectilinearity of light. But what could the model do toward explaining refraction? That question had occurred to Descartes.
But, because there is a great difference between the stick of this blind man and the air or other transparent bodies through which we see, it is necessary that I use here still another comparison.6
The second analogy served to show bow light could permeate transparent media. In it, the material particles of these bodies were portrayed by a vat's motionless grapes past which wine, representing streams of light, tended to flow. This model served to explain how light could traverse a transparent medium. But neither it nor the first analogy explained the most important phenomena of all: reflection and refraction. For that purpose, Descartes used a third analogy in which light was regarding as a stream of moving balls.
It would seem obvious that Descartes was merely using models, rather than telling us what light really was; for three things at once, light could not be, especially since flying balls, rigid sticks, and the wine in a vat of grapes all behave quite differently. Descartes said as much at the end of his Principles of philosophy. Principle 204 in part IV asserts that concerning things not directly accessible to sense-perception, it suffices to describe their nature, to say what they would be like-even if by chance they should not be S0.7 William Molyneux said the same sort of things. in 1690.
I know some will say, that by Natural Philosophy is meant not only the Knowledge of the Properties and Uses of Natural Bodies; but also the Assigning the true Reasons or Causes of these Properties. But in this Particular we are to proceed with great Caution. I know the Mind of man is of that inquisitive, prying Nature; that upon any Appearance offer'd to the Senses, it immediately falls to the search after the Cause producing this Effect. But indeed in Natural Disquisitions, 'tis generally (I may say almost alwayes) to no purpose. We may make plausible Conjectures, and some sort of feasible Guesses; but others perhaps may make others, and these also equally probable. But these deserve not the Name of Natural Philosophy; they serve only for Chat and Diversion. For the Omnipotent Contriver of the Universe has order'd Natures Operations to be performed by such fine Springs, Secret Motions, and inexplicable Ways; that Man in this Life may well despair of attaining the intimate Knowledge thereof; and must therefore content himself with the Contemplation of plain matter of Fact, in which he cannot be deceived.8Thus it seems plausible that mechanism might have been methodology rather than metaphysics. So much the worse, for if it be shown that what seems plausible is false, rather than true, there arises the further task of accounting for the plausibility. That is precisely our position, for mechanism was indeed full-blown metaphysics. Descartes' disclaimer was given simply because of a standard metaphysician's problem-he could not incontrovertibly prove his point. Barking at the heels of scholastics who thought they could, in all candor Descartes had to admit his limitation. How can one prove that the world is really Ideas at base, or processes, or matter in motion? Such contentions cannot be demonstrated as could the presence of a 30-foot green snake underneath my desk. Descartes was logician enough to realize what he could not do; he was human enough to do it anyway. His disclaimer was immediately followed by the statement that nevertheless there is a moral certainty that everything is such as has been shown it could be.9 Moral certainty was all that men, not being God, could attain. But immediately in the next breath, Descartes took the full step backwards, to claim that . . . in reality
We have full and absolute assurance that the world is as he said. In his words.. .
at least the more general things which I have written about the world and earth, can scarcely be made intelligible by any means other than as explained by me.11
So from methodology, through moral certainty, Descartes ascended to absolute certainty in metaphysics. Descartes could not make the move in one big step. He had to do it a little at a time.
Why, if Descartes was actually talking about the nature of the world rather than about a method, would he tender explanations as tenuous as that of magnetism, and as contradictory as that of light? Bear in mind, the problem does not concern merely Descartes himself, but involves him as a spokesman for his whole age, whose motivation consisted chiefly in a rejection of what had gone before. They believed that the world was mechanical and rationally understandable, and were extremely zealous to make their case. Were their explanations speculative? At least the explanations were mechanical. If Descartes proffered three clash ing mechanical explanations of light, at least he had given three mechanical explanations. In that respect, they were thrice as good as one. The important goal was to establish the mechanical philosophy; details be damned.
It was because of the success of mechanics in the hands of Galileo, its amenability to mathematics, and the promise it offered in associating the unobservable with the observable, that mechanics presented itself at all. But why did it become metaphysics rather than just a method? The explanation lies in the youth of the age. At its inception early in the seventeenth century, modem science criticized earlier efforts at final and complete explanation of the world. There is no doubt that from antiquity through the middle ages, science was hardly limited merely to measuring and describing the appearances. Rather, the intent was to tender final explanations in terms of necessary principles. Scepticism increased in the renaissance. By the early seventeenth century, depreciation of medieval science was nothing novel. But no viable alternative had arisen; mysticism died rather early in its infancy. To widespread applause Descartes doubted away the Aristotelian world, and the resultant vacuum was unbearable. He and his century proclaimed that they could not really press through to the heart of nature, men could not know what lay bidden from their senses. All that science could do was describe the apparent phenomena; the human mind could not penetrate behind them. But the pill was too bitter to swallow. The empty frame had to be refilled with a new picture. So having claimed that they could not explain, but merely describe, the age promptly began to explain, and to explain exactly the same phenomena as had the Aristotelians, often in the very same order. (Of course, the explanations were mechanistic.) Descartes' Meteores rigidly followed Aristotle's Meteorologica topic by topic, not merely because that was a logical way to arrange a rebuttal; but because the horror of an intellectual vacuum demanded that each old explanation be replaced by a new one. Mere observational descriptions alone would not suffice. Errors of detail could be forgiven, just so long as the holes were filed with mechanistic plugs.
It would be a matter of some time before modem science was mature and stable enough to forego trying to lay nature bare and trying to find one simple key to all her secrets, to desist from inferring that, since nature was not unknowable, it was thus known, and to stop confusing a hope with a fact. It comes hard to admit that there is no ready road to truth, and no final certainty in science. That is why mechanical philosophers could say no other than that something real and knowable lay behind observed phenomena. Their particular twist was to claim it was mechanical.
In laying the foundations for modem science what really mattered was not the collection of observably verifiable facts. It was the development of a view of the world and a corresponding method of investigation -neither of which can be shown incontrovertibly to be correct. Seventeenth-century mechanical philosophers were not afraid to take such a bold step.