The Atom in the History of Human Thought

25 June 2002

by Bernard Pullman (late professor of Quantum Chemistry at the Sorbonne, and director, Institut de Biologie Physico-Chimique, France), Oxford University Press, ISBN 0195114477, £14.95 (€23). Translated from the original French, Editions Fayard, ISBN 2213594635, 729.3.


“This book endeavours to describe the turbulent relationship between atomic theory and philosophy and religion over a period of 25 centuries,” states the preface – a daunting task by any standards. Pullman admits that he is neither a philosopher nor a man of religion, but a chemist “having long lived side-by-side with atoms”. As such, he achieves a great deal.

The book begins with the birth of the atomic theory – the “Greek miracle” of the 7th-5th centuries BC in Pullman’s words, when a few Hellenic thinkers shed the Greek pantheon in favour of a natural philosophy. This began with theories advocating various primordial substances – water (Thales), air (Anaximenes), fire (Heraclitus) and earth (Xenophanes) – from which all things come to be. The two fundamental concepts of atomism – impenetrable, indivisible (atomos) corpuscles and void through which they travel – were formulated around 450 BC by Leucippus and Democritus, and refined a century later by Epicurus and Lucretius to a logical structure that remained essentially unchanged for the next 2000 years. The book also touches on Hindu and Buddhist atomism, which evolved independently at about the same time, but had no impact on the atomic theory of the Western world.

The book then moves on to “a few scattered revivals” during the 1st-15th centuries AD. After describing the antiatomistic position of the Church as put forward by Basil of Caesarea, St Augustine and Thomas Aquinas (among others), some mediaeval Christian atomists make an appearance. These are divided into chroniclers (such as Isidore de Seville), sympathizers and proponents. The sympathizers include Adelard of Bath (a translator of scientific Arab texts) and Thierry of Chartres (a reviver of the works of antiquity). Among the proponents are Constantine the African, a physician from Carthage who explicitly defined atoms as the fundamental constituents of substances; William of Conches; and William of Ockham.

Jewish philosophy from the 9th to the 13th centuries is discussed. This was largely opposed to atomism, although Moses Maimonides (1135-1204) described the teaching of the Arab atomists. The schismatic Jewish sect of the Karaites (founded in the 8th century) adopted the atomic theory borrowed directly from teachings of Muslim philosophers and theologians.

While Greek atomism was to free mankind from invisible powers, Arab atomism is decidedly religious in nature. The Arab atomic doctrine is expressed in the Kalam, a set of 12 propositions, one of which introduces the notion of “accidents”. These reside within atoms, and include characteristics such as life and intelligence, along with inanimate properties such as colour and odour.

Moving into the Renaissance and the age of enlightenment, Pullman describes the resurgence of atomic theory starting with Pierre Gassendi, who is counted among the Christian atomists along with the likes of Galileo, Bruno, Newton and Boyle. Gassendi criticized Aristotle and defended ancient atomists, especially Epicurus, whose teachings he tried to make acceptable to the Church. The doctrine of John Locke, who doubted any future experimental proof of the existence of these atoms, is labelled “agnostic atomism”. Pullman also discusses Maupertuis and Diderot, with their sensitive and intelligent atoms; Holbach, with his materialistic atoms; and Maxwell, who believed that atoms exist due to the action of a creator.

Christian antiatomists – philosophers or scientists who use religious arguments to reject the theory – include Descartes, who rejected the concept of void; and Leibniz with his metaphysical atoms (monads). Others mentioned are Roger Boscovitch, who tried to blend Leibniz’s monads with Newton’s laws of attraction and repulsion; George Berkeley, who rejected matter, material corpuscles and void; and Immanuel Kant, who is labelled an “atomist turned antiatomist”.

The final part of the book moves into the modern era with the advent of scientific atomism through the 19th and 20th centuries. Pullman begins with the demise of the 2000-year-old theory of four elements by the demonstration of Lavoisier that water, and of Cavendish and Priestley that air, have a compound structure. Elements came to be defined as substances that could not be decomposed. Confusion over nomenclature followed until Canizzaro formulated a distinction between atoms and molecules in 1860. Soon afterwards, Mendeleev arranged the first 63 elements in the periodic table.

Controversy, however, continued. Philosophers such as Hegel and Schopenhauer were both opposed to atomism. So were die-hard antiatomists like Berthelot, Mach and Ostwald, and a few that Pullman calls “nostalgic philosophers”, such as Nietzsche, Marx and Bergson.

Nevertheless, atomic theory was almost universally accepted by the time J J Thomson discovered the electron in 1897, bringing the hypothesis of indivisible atoms to an end.

Pullman then brings us into the quantum age in 1900 with Planck’s famous constant. He guides us through Rutherford’s 1911 conclusion that atoms are mainly vacuum with a tiny nucleus surrounded by electrons, to Bohr’s 1913 observation that Planck’s constant leads to stable orbits in the atom and to discrete spectral lines. The rest of the modern atomic picture is carefully covered, with Chadwick’s 1932 discovery of the neutron; de Broglie’s postulation of the wave-like character of matter particles, and its subsequent confirmation by Davisson and Germer; and Schrödinger’s wave mechanics leading to serious conceptual difficulties among scientists.

Chemical bonding naturally plays a large part in the book, given that its author was a chemist. Covalent bonding, where electrons are shared between atoms, leads Pullman to an interesting analogy developed in the chapter “Society of atoms: marriage”, where he concludes that “as always in life, this implies the ability and even obligation both to give and to receive”.

In a closing chapter, Pullman delves into the nanoworld. Here he describes how the scanning-tunnel microscope and the atomic-force microscope led to visualization and manipulation of single atoms interacting with bulk surfaces, and how complete isolation of single (charged) atoms surrounded by vacuum was accomplished using ion traps.

No-one can contest that the atoms conceived 2500 years ago as invisible and indivisible impenetrable philosophical constructs have today become divisible and visible objects of reality. But are they really in human thought? They are certainly in the thoughts of scientists and philosophers, but I doubt they are uppermost in the minds of most people, as Pullman suggests when he claims that “quantum physics has stoked an interest in the ‘problem of God’ among a general public”. The book is let down by its index, which is difficult to use and occasionally inaccurate. That said, however, to read this book is a fruitful learning exercise, and it has a host of informative notes.


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