An Introduction to the History of Science

by Walter Libby

For part of this theory Kant was indebted to Thomas Wright of Durham (1711-1786). Wright was the son of a carpenter, became apprenticed to a watchmaker, went to sea, later became an engraver, a maker of mathematical instruments, rose to affluence, wrote a book on navigation, and was offered a professorship of navigation in the Imperial Academy of St. Petersburg. It was in 1750 that he published, in the form of nine letters, the work that stimulated the mind of Kant, An Original Theory or New Hypothesis of the Universe. The author thought that the revelation of the structure of the heavens naturally tended to propagate the principles of virtue and vindicate the laws of Providence. He regarded the universe as an infinity of worlds acted upon by an eternal Agent, and full of beings, tending through their various states to a final perfection. Who, conscious of this system, can avoid being filled with a kind of enthusiastic ambition to contribute his atom toward the due admiration of its great and Divine Author?

Wright discussed the nature of mathematical certainty and the various degrees of moral probability proper for conjecture (thus pointing to a distinction that ultimately became basal in the philosophy of Kant). When he claimed that the sun is a vast body of blazing matter, and that the most distant star is also a sun surrounded by a system of planets, he knew that he was reasoning by analogy and not enunciating what is immediately demonstrable. Yet this multitude of worlds opens out to us an immense field of probation and an endless scene of hope to ground our expectation of an ever future happiness upon, suitable to the native dignity of the awful Mind which made and comprehended it.

The most striking part of Wright's Original Theory relates to the construction of the Milky Way, which he thought analogous in form to the rings of Saturn. From the center the arrangement of the systems and the harmony of the movements could be discerned, but our solar system occupies a section of the belt, and what we see of the creation gives but a confused picture, unless by an effort of imagination we attain the right point of view. The various cloudy stars or light appearances are nothing but a dense accumulation of stars. What less than infinity can circumscribe them, less than eternity comprehend them, or less than Omnipotence produce or support them? He passes on to a discussion of time and space with regard to the known objects of immensity and duration, and in the ninth letter says that, granting the creation to be circular or orbicular, we can suppose in the center of the whole an intelligent principle, the to-all-extending eye of Providence, or, if the creation is real, and not merely ideal, a sphere of some sort. Around this the suns keep their orbits harmoniously, all apparent irregularities arising from our eccentric view. Moreover, space is sufficient for many such systems.

Kant resembled his predecessor in his recognition of the bearing on moral and religious conceptions of the study of the heavens and also in his treatment of many astronomical details, sometimes merely adopting, more frequently developing or modifying, the teachings of Wright. He held that the stars constitute a system just as much as do the planets of our solar system, and that other solar systems and other Milky Ways may have been produced in the boundless fields of space. Indeed, he is inclined to identify with the latter systems the small luminous elliptical areas in the heavens reported by Maupertuis in 1742. Kant also accepted Wright's conjecture of a central sun or globe and even made selection of one of the stars to serve in that office, and taught that the stars consist like our sun of a fiery mass. One cannot contemplate the world-structure without recognizing the excellent orderliness of its arrangement, and perceiving the sure indications of the hand of God in the completeness of its relations. Reason, he says in the Allgemeine Naturgeschichte, refuses to believe it the work of chance. It must have been planned by supreme wisdom and carried into effect by Omnipotence.

Kant was especially stimulated by the analogy between the Milky Way and the rings of Saturn. He did not agree with Wright that they, or the cloudy areas, would prove to be stars or small satellites, but rather that both consisted of vapor particles. Giving full scope to his imagination, he asks if the earth as well as Saturn may not have been surrounded by a ring. Might not this ring explain the supercelestial waters that gave such cause for ingenuity to the medieval writers? Not only so, but, had such a vaporous ring broken and been precipitated to the earth, it would have caused a prolonged Deluge, and the subsequent rainbow in the heavens might very well have been interpreted as an allusion to the vanished ring, and as a promise. This, however, is not Kant's characteristic manner in supporting moral and religious truth.

To account for the origin of the solar system, the German philosopher assumes that at the beginning of all things the material of which the sun, planets, satellites, and comets consist, was uncompounded, in its primary elements, and filled the whole space in which the bodies formed out of it now revolve. This state of nature seemed to be the very simplest that could follow upon nothing. In a space filled in this way a state of rest could not last for more than a moment. The elements of a denser kind would, according to the law of gravitation, attract matter of less specific gravity. Repulsion, as well as attraction, plays a part among the particles of matter disseminated in space. Through it the direct fall of particles may be diverted into a circular movement about the center toward which they are gravitating.

Of course, in our system the center of attraction is the nucleus of the sun. The mass of this body increases rapidly, as also its power of attraction. Of the particles gravitating to it the heavier become heaped up in the center. In falling from different heights toward this common focus the particles cannot have such perfect equality of resistance that no lateral movements should be set up. A general circulatory motion is in fact established ultimately in one direction about the central mass, which receiving new particles from the encircling current rotates in harmony with it.

Mutual interference in the particles outside the mass of the sun prevents all accumulation except in one plane and that takes the form of a thin disk continuous with the sun's equator. In this circulating vaporous disk about the sun differences of density give rise to zones not unlike the rings of Saturn. These zones ultimately contract to form planets, and as the planets are thrown off from the central solar mass till an equilibrium is established between the centripetal and centrifugal forces, so the satellites in turn are formed from the planets. The comets are to be regarded as parts of the system, akin to the planets, but more remote from the control of the centripetal force of the sun. It is thus that Kant conceived the nebular hypothesis, accounting (through the formation of the heavenly bodies from a cloudy vapor similar to that still observable through the telescope) for the revolution of the planets in one direction about the sun; the rotation of sun and planets; the revolution and rotation of satellites; the comparative densities of the heavenly bodies; the materials in the tails of comets; the rings of Saturn, and other celestial phenomena. Newton, finding no matter between the planets to maintain the community of their movements, asserted that the immediate hand of God had instituted the arrangement without the intervention of the forces of Nature. His disciple Kant now undertook to explain an additional number of phenomena on mechanical principles. Granted the existence of matter, he felt capable of tracing the cosmic evolution, but at the same time he maintained and strengthened his religious position, and did not assume (like Democritus and Epicurus) eternal motion without a Creator or the coming together of atoms by accident or haphazard.

It might be objected, he says, that Nature is sufficient unto itself; but universal laws of the action of matter serve the plan of the Supreme Wisdom. There is convincing proof of the existence of God in the very fact that Nature, even in chaos, cannot proceed otherwise than regularly and according to law. Even in the essential properties of the elements that constituted the chaos, there could be traced the mark of that perfection which they have derived from their origin, their essential character being a consequence of the eternal idea of the Divine Intelligence. Matter, which appears to be merely passive and wanting in form and arrangement, has in its simplest state a tendency to fashion itself by a natural development into a more perfect constitution. Matter must be considered as created by God in accordance with law and as ever obedient to law, not as an independent or hostile force needing occasional correction. To suppose the material world not under law would be to believe in a blind fate rather than in Providence. It is Nature's harmony and order revealed to our understanding that give us a clue to its creation by an understanding of the highest order.

In a work written eight years later Kant sought to furnish people of ordinary intelligence with a proof of the existence of God. It might seem irrelevant in such a production to give an exposition of physical phenomena, but, intent on his method of mounting to a knowledge of God by means of natural science, he here repeats in summarized form his theory of the origin of the heavenly bodies. Moreover, the influence of his astronomical studies persisted in his maturest philosophy, as can be seen in the well-known passage at the conclusion of his ethical work, the Critique of the Practical Reason (1788): "There are two things that fill my spirit with ever new and increasing awe and reverence—the more frequently and the more intently I contemplate them—the star-strewn sky above me and the moral law within." His religious and ethical conceptions were closely associated with—indeed, dependent upon—an orderly and infinite physical universe.