Pierre Louis Moreau de Maupertuis

“ Let us leave such trifling arguments to those who haven't learned to laugh at them yet.
Another type of philosopher goes to the other extreme. Finding all too few traces of intelligent design in Nature, he disregards all final causes and believes that world formed itself as it is from pure matter and its motion. The first type sees an Intelligent Designer everywhere; the other sees Him nowhere, believing rather that a soulless mechanics was able to form bodies as sophisticated as animals and plants and to bring about all the wonders of the universe (Descartes, Princip. L'Homme de Descartes) . ”

“ Animals without mouths cannot live; those lacking organs of generation cannot reproduce themselves. The few animals that have survived are those with well-ordered parts suited to survival; thus, the animals that we see today are but the smallest part of those produced by a soulless universe.
Almost all of the modern authors that consider physics and natural history merely extend the old arguments of the organization of animals and plants, pushing them into ever finer details of Nature. ”

“ Whether a material body should travel from one point to another without encountering an obstacle, or encountering an impenetrable obstacle, Nature always leads it along the path of shortest distance and briefest time.
To apply this principle to refraction, let us consider two transparent media separated by the plane of their common surface. Suppose that the light's point of departure is within one medium, whereas its point of arrival is in the other medium, but that the line joing the two points is not perpendicular to the surface separating the media. ”

“ This is the principle of least action, a principle so wise and so worthy of the supreme Being, and intrinsic to all natural phenomena; one observes it at work not only in every change, but also in every constancy that Nature exhibits. In the collision of bodies, motion is distributed such that the quantity of action is as small as possible, given that the collision occurs. At equilibrium, the bodies are arranged such that, if they were to undergo a small movement, the quantity of action would be smallest. ”

“ These philosophers assign the cause of motion to God because they don't know where else to put it; they resort to an immaterial Being, since they can't imagine that matter should have the power to produce, distribute and destroy motion. But it's important to realize that all the laws of motion and equilibrium should be based on a suitable principle, if we are to use them to prove God's existence, regardless of whether bodies can act directly on each other, or whether they use some other interaction as yet poorly understood. ”

“ From the all too few ancient geometers who undertook such studies, we have little that is intelligible or well-founded. The perfection which geometry has acquired since their time puts us in a better position to succeed, and may more than compensate for the advantages that those great minds had over us. ”

“ Those who have reviewed such arguments have not examined their strength nor scope. Many things in the universe suggest that it is governed by a blind power. On all sides, we see consequences of effects leading to some destination; but this does not prove intelligent design. We must rather seek signs of God's wisdom in the goals of His designs; wonderful skill in execution cannot compensate for a senseless undertaking. Skill applied senselessly is not admirable; one would blame the builder all the more if he used skill to construct a machine that was useless or even dangerous. ”

“ To unify the certainty of our research with its breadth, it is necessary to use both types of study. Let us calculate the motion of bodies, but also consult the plans of the Intelligence that makes them move. ”

“ Certain philosophers of antiquity held that movement does not exist. An overly subtle use of their minds denied the evidence of their own senses. The difficulties they had in conceiving how a body could move, made them deny that bodies moved or even could move. Without delving into the arguments upon which they tried to base their opinion, we note that one cannot deny motion except by arguments that deny the reality of objects outside ourselves, arguments that reduce the universe to us, and all phenomena to our perceptions.
It is true that we know motion only through our senses ”

“ After so many great men have worked on this subject, I almost do not dare to say that I have discovered the universal principle upon which all these laws are based, a principle that covers both elastic and inelastic collisions and describes the motion and equilibrium of all material bodies. ”

“ It seems that the ancient philosophers made the first attempts at this sort of science, in looking for metaphysical relationships between numbers and material bodies. When they said that God occupies himself with geometry, they surely meant that He unites in that science the works of His power with the perspectives of His wisdom. ”

“ Of those who have applied themselves to studying the Universe, several have found traces of the wisdom and power of Him who governs it. The more the field of physics has progressed, the more arguments we find for His existence. However, some have been confused by the character of the Divinity revealed in Nature, while others, almost religiously zealous, have given too much weight to some arguments, considering them proofs when they were not. ”

“ The first type of studies is more within our power, but does not take us far. The second type may lead us stray, since we do not know enough of the goals of Nature and we can be mistaken about the quantity that is truly the expense of Nature in producing its effects. ”

“ The laws of motion and equilibrium derived from this principle are exactly those observed in Nature. We may admire the applications of this principle in all phenomena: the movement of animals, the growth of plants, the revolutions of the planets, all are consequences of this principle. The spectacle of the universe seems all the more grand and beautiful and worthy of its Author, when one considers that it is all derived from a small number of laws laid down most wisely. ”

“ A blind and deterministic mechanics follows the plans of a perfectly clear and free Intellect. If our spirits were sufficiently vast, we would also see the causes of all physical effects, either by studying the properties of material bodies or by studying what would most suitable for them to do. ”

“ To identify the original cause of motion, the greatest philosopher of antiquity resorted to a Prime Mover, itself unmovable and indivisible. A modern philosopher has not only recognized God as the author of all motion of material particles, but also argued that God's direct intervention is continually necessary for every change and redistribution of motion. Not being able to understand how bodies can move other bodies, he denied that they did and concluded that when bodies hit or press on other bodies, it is God who makes them move; their impact is nothing but a prompting for God to move them. ”

“ If we assume, as seems reasonable, that light moves more quickly in air than it does in water, then the bent path taken by the light causes it to move from its departure point to its arrival point in the briefest possible time. ”

“ If you assume that speed must change by degrees, doesn't it change discontinuously between degrees? Even imperceptible discontinuous changes would violate the law of continuity as much as the sudden destruction of the universe.
The experiments suggest that it is easy to confuse hardness with elasticity, but they do not show that all hard bodies are elastic. On the contrary, those who have considered the impenetrability of bodies suggest that perfect inelasticity is a necessary consequence of matter. ”

“ We should at least examine the strengths and weaknesses of each argument, to give each one its proper weight; for one can do no greater damage to Truth than to base it on false reasoning.
I will not consider here arguments based on an infinite Being, arguments that seem to prove that an infinitely perfect Being must exist; for that idea is so sublime that, from our finite vantage point, we cannot find a reliable foundation upon which to build reasoned arguments. ”

“ We see only that material bodies can extract motion from each other.
The material particles moving in Nature received their motion from an external cause that is unknown hitherto. The particles are themselves indifferent to motion or rest; if at rest, they stay so, whereas moving bodies continue to move until something changes their motion. When a moving particle of matter encounters another particle at rest, it passes on some or all of its motion. Every collision of two bodies (whether one is at rest and the other moves, or both are moving) is accompanied by a change in motion. ”

“ These arguments are not satisfying, but neither can they be soundly refuted. Still, a true philosopher should neither be dazzled by the order and suitability of the parts of the universe, nor seek to grasp things that lie beyond Nature. Despite the disorder observed in Nature, one finds enough traces of the wisdom and power of its Author that one cannot fail to recognize Him. ”

“ The quantity of action is the product of the mass of the bodies times their speed and the distance they travel. When a body is transported from one place to another, the action is proportional to the mass of the body, to its speed and to the distance over which it is transported. ”

“ Laws of Motion for Inelastic Bodies Let there be two inelastic bodies of masses and moving in the same direction with speeds and , respectively. Let the first mass move more quickly, so that it overtakes the second mass and collides with it. After the collision, let the common velocity of the two bodies be such that . The change in the universe is that, whereas the first mass was moving at a speed and was covering a distance per unit time, it now moves only at a speed and covers only a distance per unit time ”

“ Momentum is conserved only in special cases, and kinetic energy is conserved only for certain types of bodies. Neither one represents a universal principle, a general law of motion.
If one studies these principles and the reasoning their authors used, it is surprising that they ever were able to derive them; one suspects that they worked backwards from experience, rather than deducing them from basic principles. Those who argue most rigorously recognize that the principle used to derive the collision laws for elastic bodies would not be applicable to perfectly inelastic bodies. ”

“ More industrious and sensible philosophers judged only that it would be difficult to understand the principles of motion, and invented reasons to despair of ever knowing them, as an excuse to get out of doing experiments.
A true philosopher does not engage in vain disputes about the nature of motion ”

“ The two alternatives, Intelligent Design versus pure chance, are based on our inability to find a physical cause for the uniformity of planetary motion within Newton's system. However, other philosophers have hypothesized a fluid that transports the planets or at least regulates their motion; if true, that might explain the uniformity of planetary motion (rather than an Intelligent Designer or pure chance) and would be no more proof of God's existence than any other motion imposed on matter.
I don't know whether Newton's argument based on the construction of animals is much better. ”

“ Admittedly, such research is more difficult than studying an insect, a flower, or similar things that Nature offers to our eyes every moment. But we can be aided in our difficult march by a guide, one who is sure-footed although he has not yet gone where we would like to go.
Until now, the goals of mathematics have rarely gone beyond coarse needs of the body and useless speculations of the spirit. ”

“ The motive force (i.e., the ability of a moving body to move other bodies) is just terminology filling in for understanding and has no meaning beyond the results of phenomena. It is only mental habit that prevents us from realizing how miraculous it is that motion can be passed from one body to another. Once our eyes have opened, nothing is so striking. ”

“ We have experienced the impenetrability of a material body, we have proven to ourselves that a certain force is required to change its motion, we have seen that the collision of two bodies causes them to stop or be reflected or displace a resting body or, more generally, change their speed. ”

“ What is this power that bodies seem to have to act on one another?
We observe that some particles of matter are in motion, while others are at rest. Hence, motion is not an essential property of matter ”