Isaac Newton developed an unusual and little-known theory of subterranean metal and mineral formation by integrating concepts drawn from his own alchemical experimentation and reading with the mechanical philosophy that he inherited from other seventeenth-century figures such as René Descartes and Robert Boyle. Until recently, Newton’s geochemical theory has been known incompletely, since the primary text in which it is found, Smithsonian MS Dibner 1031B, had only been published in a fragmentary form. Thanks to the 2006 edition of the complete manuscript appearing on the online Chymistry of Isaac Newton site ( www.chymistry.org ), it is now possible to arrive at a far more complete understanding of Newton’s early theory of metallogenesis than before. The present paper provides a concise analysis of Newton’s views on this subject, showing how he integrated themes from alchemy and the better-known parts of his natural philosophy to arrive at a novel theory of the production of metals and minerals within the earth.

Theory choice, the problem of accepting/rejecting scientific theories, is philosophically interesting in part because it involves appeal to nonempirical factors that can only be justified by philosophical considerations. The emphasis in this paper is on the historical as opposed to the experimental sciences—including astronomy, evolutionary biology, and especially historical geology—with examples taken from seventeenth through nineteenth centuries. The fact that evidential reasoning inherently requires a choice of philosophical/methodological principles is demonstrated through reference both to historical cases and to general philosophical considerations. This paper argues that methodological principles play a crucial role in turning empirical data into evidence for/against theories, and it outlines some of the particular evidential and methodological difficulties faced in the historical sciences. Choices of methodological principles depend on nonempirical factors, and because definitive arguments can rarely be found, they are largely a matter of judgment. “Scientific” debates are thus sometimes really disputes over philosophical taste and judgment. Moreover, it is often the case that clear judgments about the incorrectness/correctness of a methodological principle used in a specific context can only be made retrospectively. In part by looking at connections among Isaac Newton, David Hume, and Charles Lyell, and in part by examining Lyell’s own arguments, I argue that it was reasonable for Lyell to adopt uniformitarianism as a central methodological principle. Through arguments and historical examples, I also show that there are limits to the acceptability of the uniformitarian position.

Abstract From ancient times through to the Renaissance reports of stones, fragments of iron and ‘six hundred other things’ fallen from the sky were written down in books. With few exceptions, these were taken as signals of heaven's wrath. The 18th century Enlightenment brought an entirely new approach in which savants sought rational explanations, based on the laws of physics, for unfamiliar phenomena. They accepted Isaac Newton's dictum of 1718 that outer space must be empty in order to perpetuate the laws of gravitation, and, at the same time, they rejected an old belief that stones can coalesce within the atmosphere. Logically, then, nothing could fall from the skies, except ejecta from volcanoes or objects picked up by hurricanes. They dismissed reports of fallen stones or irons as tales told by superstitious country folk, and ascribed stones with black crusts to bolts of lightning on pyritiferous rocks. The decade between 1794 and 1804 witnessed a dramatic advance from rejection to acceptance of meteorites. The three main contributing factors were E.F.F. Chladni's book of 1794, in which he argued for the actuality of falls and linked them with fireballs; the occurrence of four witnessed and widely publicized falls of stones between 1794 and 1798; and chemical and mineralogicai analyses of stones and irons, published in 1802 by Edward C. Howard and Jacques-Louis de Bournon. They showed that stones with identical textures and compositions, very different from those of common rocks, have fallen at different times in widely separated parts of the world. They also showed that erratic masses of metallic iron and small grains of iron in the stones both contain nickel, so they must share a common origin. Meanwhile, in 1789, Anton-Laurent de Lavoisier had revived the idea of the accretion of stones within the atmosphere, which became widely accepted. Its chief rival was a hypothesis that fallen stones were erupted by volcanoes on the Moon. During the first half of the 19th century falls of carbonaceous chondrites and achondrites, and observations on the metallography of irons, provided fresh insights on the range of compositions of meteorite parent bodies. By 1860 both of the two main hypotheses of origins were abandoned, and debates intensified on whether all meteorites were fragments of asteroids or some of them originated in interstellar space. This paper will trace some of the successes and some of the failures that marked the efforts to gain a better understanding of meteorite falls from the end of the 15th century to the early 20th century.