Gottfried Wilhelm Leibniz Writes Against Barbaric Physics and Gravitational Attraction

One of the very first posts that I published on this blog was entitled The Best of All Possible Worlds. Therein, I presented the following paragraph from the correspondence between Gottfried Wilhelm Leibniz (1646-1716) and Samuel Clarke (1627-1729)¹:

Sir Isaac Newton and his followers also have a very odd opinion concerning the work of God. According to them, God Almighty needs to wind up his watch from time to time, otherwise it would cease to move. He had not, it seems, sufficient foresight to make it a perpetual motion. No, the machine of God’s making is so imperfect, according to these gentlemen, that he is obliged to clean it now and then by an extraordinary concourse, and even to mend it, as a clockmaker mends his work, who must consequently be so much the more unskillful a workman as he is more often obliged to mend his work and to set it right. [pp.320-321]

So I knew that Leibniz had correctly criticized the theory of gravitation as defined by Isaac Newton (1643-1727) for being unstable. However, I had not fully understood that Leibniz completely rejected any form of attraction or repulsion, or action-at-a-distance. This opposition he made completely clear in a pamphlet entitled “Against Barbaric Physics”². In this post, I will present some excerpts from that text.

Leibniz begins as follows:

It is, unfortunately, our destiny that, because of a certain aversion toward light, people love to return to darkness. We see this today, where the great ease for acquiring learning has brought forth contempt for the doctrines taught, and an abundance of truths of the highest clarity has led to a love for difficult nonsense. Clever people have such a lust for variety that, in the midst of an abundance of fruits, it seems they want to revert to acorns. [In the medieval period, when crops failed, poor peasants scavenged for any possible food source, including acorns in the woods.] That physics which explains everything in the nature of body through number, measure, weight, or size, shape and motion, which teaches that nothing is moved naturally except through contact and motion, and so teaches that, in physics, everything happens mechanically, that is, intelligibly, this physics seems excessively clear and easy. [p.312, my emphasis]

So Leibniz claims that nothing moves “except through contact and motion”, and that “everything happens mechanically”. Furthermore, all those who have different ideas “love to return to darkness”.

He first takes to task those who call for various deities or spirits to intervene for the running of the cosmos:

These barely skilled judges think that divine works are necessary, and so think that God everywhere uses little vice-deities (lest God himself has to act miraculously), just like those who once attributed the motions of the stars to their own intelligences. [p.313]

He then moves on to criticize those, such as Newton, who talk of forces in physics, saying that these forces are reminiscent of the occult [hidden] qualities used in the physics of the medieval period.

It pleases others to return to occult qualities or to Scholastic faculties, but since those crude philosophers and physicians [see that] those [terms are] in bad repute, changing the name, they call them forces. But true corporeal forces are only of one kind, namely, those arising through the impression of impetus (as for example, when a body is flung forward), which even have a role to play in insensible motions. But these persons imagine specific forces, and vary them as the need arises. They bring forth attractive, retentive, repulsive, directive, expansive, and contractive faculties. This can be forgiven in Gilbert and Cabaeus, and even quite recently in Honoratus Fabri, since the clear foundation [ratio] for philosophizing either had not yet become known, or had not yet been sufficiently appreciated. But what person of understanding would now bring forward these chimerical qualities, which have been repeatedly offered up as the ultimate principles of things? It is permissible to recognize magnetic, elastic, and other sorts of forces, but only insofar as we understand that they are not primitive or incapable of being explained, but arise from motions and shapes. However, the new patrons of such things don’t want this. It has been observed in our own times that there is a truth in the suggestion of earlier thinkers who maintained that the planets gravitate and tend toward one another. It pleased them to make the immediate inference that all matter essentially has a God-given and inherent attractive power and, as it were, mutual love, as if matter had senses, or as if a certain intelligence were given to each part of matter by whose means each part could perceive and desire even the most remote thing. [They argue] as if there were no room for mechanical explanations by which the effort [conatus] gross [crassus] bodies make in striving toward the great bodies of the cosmos could be accounted for through the motion of smaller pervading bodies. These same people threaten to give us other occult qualities of this sort, and thus, in the end, they may lead us back to the kingdom of darkness. [pp.313-314, my emphasis]

Leibniz is opposing those who might think that there are attractive or repulsive forces between different bodies. For him, all phenomena must be explainable by mechanical means, by bodies pushing each other around, possibly through the motion of smaller bodies within the aforementioned bodies.

What is striking for me is the way in which Leibniz assumes matter to be lifeless, inert, with no properties or qualities of its own. This assumption is still very much alive today, and leads to all sorts of philosophical problems, such as the inability of modern science to make any kinds of inroads in explaining the phenomena of life and consciousness.

Leibniz does not have problems with stating that there appears to be mutual gravitation between planets. What bothers him is that anyone propose that this cannot be explained through some kind of local action. People making such propositions are literally “slipping back into barbarism in physics”!

First the ancients, and on their example, many more recent people have rightly used intermediate principles for explaining the nature of things, principles that are, indeed, insufficiently explained, but principles which could be explained and which we could hope to reduce to prior and simpler principles, and, in the end, to first principles. I think that this is praiseworthy as long as composite things are reduced to simpler things. For in nature, things must proceed by steps, and one cannot go immediately to the first causes. Therefore, those who have shown that the astronomical laws can be explained by assuming the mutual gravitation of the planets have done something very worthwhile, even if they may not have given the reason for this gravitation. But if certain people, abusing this beautiful discovery, think that the explanation [ratio] given is so satisfactory that there is nothing left to explain, and if they think that gravity is a thing essential to matter, then they slip back into barbarism in physics and into the occult qualities of the Scholastics. They even fabricate what they cannot prove through the phenomena, for so far, except for the force by which sensible bodies move toward the center of the earth, they have not been able to bring forward any trace of the general attraction of matter in our region. [p.314, my emphasis]

For Leibniz, the attractive and repulsive forces being used in England are reminiscent of previous occult concepts, such as sympathy or antipathy, or heat, old, moistness and dryness.

But some people have added qualities which they have also called faculties, virtues, and most recently, forces. Such were the sympathy or antipathy, or strife and friendship of Empedocles; such were heat, cold, moistness, and dryness, the four primary qualities of the Peripatetics and followers of Galen; such were the sensible and intentional species of the Scholastics, and also the expulsive, retentive, and change-causing faculties of the physicians who taught in barbaric times. More recently, Telesio has tried to set many things straight with operant heat, and some chemists, especially the followers of [J.B.] van Helmont and Marcus Marci, have introduced certain effective ideas [ideas operatrices]. Most recently in England, some have tried to bring back attractive and repulsive forces, about which we shall soon have more to say. [p.315, my emphasis]

Leibniz does not just take Newton to task, but also William Gilbert (1544-1603) and Johannes Kepler (1571-1630).

But many sensible effects remain which we have not been able to reduce to sensible causes, like the workings of the magnet, or like the particular powers [vires] that belong to simple things, no trаce of which is found in the parts derived from them through chemical analysis, as, for example, to be the case with poisonous or medicinal plants. Here we sometimes turn to analogy, and we are not doing badly if we can explain many things on the example and likeness of few. Thus having observed the attraction and repulsion of certain things, such as magnets and things made of amber, it seemed that one could establish the forces that are at work there and also found in other things. And so Gilbert, who was the first to write about the magnet with care, and not without good results, conjectured that magnetism also lay hidden in many other things. In this, however, he was repeatedly mistaken, as was Kepler—in other respects a most excellent man—who devised certain attracting or repelling magnetic fibres among the planets. [p.316, my emphasis]

Leibniz truly does not mince his words, stating that his opponents have “invented qualities of eternal obscurity, mysterious, inexplicable”.

But we should criticize those who hold these subordinate principles as primitive and inexplicable, as, for example, those who fabricated miracles, or those who fabricated incorporeal ideas [sententia] that produce, regulate, and govern bodies, those who put forward the four elements or the four primary qualities as if they contain the ultimate explanation of things, or those who, uninterested in understanding the particular force by which we evacuate with pumps, the force which we find to resist our opening a bellows lacking an aperture, set up in nature which abhors, as it were, the vacuum a primitive, essential, and insuperable quality. And whoever isn’t, with us, eager to know qualities hitherto hidden, that is, unknown, has invented qualities of eternal obscurity, mysterious, inexplicable, which not even the greatest genius can know or render intelligible.

Such are those who, induced by the successful discovery that the great bodies of this planetary system have an attraction for one another and for their sensible parts, imagine that every body whatsoever is attracted by every other by virtue of a force in matter itself, whether it is as if a thing takes pleasure in another similar thing, and senses it even from a distance, or whether is is brought about by God, who takes care of this through perpetual miracle, so that bodies seek one another, as if they sensed each other. [p.317, my emphasis]

Below, Leibniz praises Galileo Galilei (1564-1642), Joachim Jungius (1587-1657), René Descartes (1596-1650) and Thomas Hobbes (1588-1679), along with Pierre Gassendi (1592-1655), apart from the latter’s ideas on atoms and the vacuum, for having “clearly purged inexplicable chimeras from physics”. I did not know who Jungius was; here is a quick summary from Leibniz himself³:

And while Joachim Jungius of Lübeck is a man little known even in Germany itself, he was clearly of such judiciousness and such capacity of mind that I know of no other mortal, including even Descartes himself, from whom we could better have expected a great restoration of the sciences, had Jungius been either known or assisted. [p.7]

According to the English-language Wikipedia entry for Jungius, he was an advocate of a “corpuscular chemistry” that assumed the conservation of mass. As for the Spanish-language Wikipedia entry, it states that Jungius was a precursor of John Ray (1627-1705), and subsequently Carl Linnaeus (1707-1778), with respect to botanical classification.

Leibniz praises Galileo, Jungius, Descartes and Hobbes for clearing away the cobwebs, and introducing a mechanical explanation for the phenomena of nature, but explains that their explanations are limited, since they did not recognize that “the laws of motion and nature have been established, not with absolute necessity, but from the will of a wise cause”.

Galileo Galilei, Joachim Jungius, René Descartes, and Thomas Hobbes, to whom one can add Gassendi and his followers, setting aside atoms and the vacuum, have quite clearly purged inexplicable chimeras from physics, and having revived Archimedes’s use of mathematics in physics, they have quite clearly purged inexplicable chimeras from philosophy and taught that everything in corporeal nature should be explained mechanically. But (not to mention, for the moment, the insufficiently trustworthy mechanical hypotheses, to which they were excessively addicted) they have not sufficiently recognized the true metaphysical principles or the explanations of motion and laws of nature that derive from them.

Therefore, I tried to fill this gap, and have at last shown that everything happens mechanically in nature, but that the principles of mechanism are metaphysical, and that the laws of motion and nature have been established, not with absolute necessity, but from the will of a wise cause, not from a pure exercise of will, but from the fitness [convenientia] of things. I have shown that force must be added to mass [massa], but that force is exercised only through an impressed impetus. [p.319, my emphasis]

For Leibniz, “force is exercised only through an impressed impetus”, i.e., force is only applied when something pushes something else. As for those like Newton, or, as we shall see in the next post, Christiaan Huygens (1629-1695) in his later years, who accepted the concepts of attractive and repulsive forces acting at a distance, they were bringing barbarism back into physics. The ideological split, the philosophical confrontation, between contact-action and far-action could not be starker.

Correction: What I wrote in the previous paragraph with respect to Huygens is incorrect. He did accept Newton’s inverse-square law for gravity, but like Leibniz, did not accept the idea of gravitational attraction. See my post Christiaan Huygens Accepts the Inverse-Square Law But Not Gravitational Attraction.

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1. G.W. Leibniz. “From the Letters to Clarke (1715-16)”. In G.W. Leibniz, Philosophical Essays. Edited and Translated by Roger Ariew and Daniel Garber. Indianapolis & Cambridge: Hackett Publishing Company, 1989. pp.320-346.

2. G.W. Leibniz. “Against Barbaric Physics: Toward a Philosophy of What There Actually Is and Against the Reversal of the Qualities of the Scholastics and Chimerical Intelligence (1710-16?)”. In G.W. Leibniz, Philosophical Essays. pp.312-320.

3. G.W. Leibniz. “Preface to a Universal Characteristic (1678-79)”. In G.W. Leibniz, Philosophical Essays. pp.5-10.