Atomism (as a philosophical theory)

Atomism is the theory that all of reality and all the objects in the universe are composed of very small, indivisible and indestructible building blocks known as atoms (from the Greek "atomos", meaning "uncuttable"). This leads logically to the position that only atoms exist, and there are no composite objects (objects with parts), which would mean that human bodies, clouds, planets, etc, all do not exist.

Traditional Atomism asserts that all physical objects consist of different arrangements of eternal atoms and the infinite void in which they form different combinations and shapes. There is no room in this theory for the concept of a God, and essentially it is a type of Materialism or Physicalism.

The Hindu Nyaya-Vaisesika school developed one of the earliest forms of Atomism in India between the 6th century B.C. and 1st Century B.C., with elaborate theories of how the four elemental atom types (with 24 different possible qualities), combine. These atoms were considered to have general (intensive and extensive) properties and specific (intensive) properties, and to combine in pairs (dyads), and then group into trios of pairs (triads), which are the smallest visible units of matter.

There was a doctrine of Buddhist Atomism, which began developing in India before the 4th Century B.C., in which there was also four kinds of atoms, corresponding to the standard elements. Each of these elements has a specific property, such as solidity or motion, and performs a specific function in mixtures, such as providing support or causing growth. The movement had a second phase during the 7th Century A.D., led by Dharmakirti, which considered atoms to be point-sized, durationless and made of energy.

Then Jain religion in India had also developed an atomic theory by the 1st Century B.C. The Jains envisioned the world as consisting wholly of atoms, except for souls. Each atom, according to Jaina philosophy, has one kind of taste, one smell, one color, and two kinds of touch, and can exist in one of two states, "subtle" (in which case they can fit in infinitesimally small spaces) and "gross" (in which case they have extension and occupy a finite space). Atoms can combine based on their eternal properties to produce any of six “aggregates” (earth, water, shadow, sense objects, karmic matter and unfit matter), similar to the Greek concept of elements.

In Western Philosophy, Atomism is usually associated with the Greek Pre-Socratic philosopher Democritus, although in reality Democritus's teacher Leucippus (5th Century B.C.) was certainly co-founder of the doctrine, and quite possibly fully responsible for it. Aristotle explicitly credited Leucippus with the invention of Atomism, although no fragments of his writings survive, and we have only a few fragments of the writing of Democritus (and most of that second-hand).

Democritus and Leucippus taught that the hidden substance in all physical objects consists of different arrangements of atoms and void. Both atoms and the void were never created, and they will be never ending. The void is infinite and provides the space in which the atoms can pack or scatter differently. The different possible packings and scatterings within the void make up the shifting outlines and bulk of the objects that we feel, see, eat, hear, smell, and taste. While we may feel hot or cold, "hot" and "cold" actually have no real existence, but are simply sensations produced in us by the different packings and scatterings of the atoms in the void that compose the object.

Plato objected to the mechanistic purposelessness of the Atomism of Democritus, arguing that atoms just crashing into other atoms could never produce the beauty and form of the world. For Plato, the four simple bodies (fire, air, water and earth) were geometric solids, the faces of which were, in turn, made up of triangles. Since the simple bodies could be decomposed into triangles, the triangles could be reassembled into atoms of different elements and substances.

Aristotle asserted that the elements of fire, air, earth, and water were not made of atoms, but were continuous. He considered the existence of a void, which was required by atomic theories, to violate physical principles, and speculated that change took place not by the rearrangement of atoms to make new structures, but by transformation of matter from what it was in potential to a new actuality. Aristotle represented the first important movement away from Atomism.

Epicurus was a follower of Democritus's Atomism, although he questioned how specific natural phenomena (such as earthquakes, lightning, comets or the phases of the Moon) could be explained by this theory. Other Epicurean students, particularly Lucretius (99 - 55 B.C.), fleshed out Atomism, and described how the universe began its current stage (after collisions that shatter large objects into smaller objects, the resulting dust, still composed of the same eternal atoms as the prior configurations of the universe, falls into a whirling motion that draws the dust into larger objects again to begin another cycle).

Aristotelian philosophy eclipsed the importance of the Atomists, and there was little interest expressed in the idea throughout the whole of the medieval period until its resurrection in the 16th and 17th Century, although the Islamic Ash'arite school of philosophy, notably al-Ghazali (1058 - 1111), propounded a type of hybrid Atomism where atoms are the only perpetual, material things in existence, and all else in the world is “accidental” (lasting for only an instant), and contingent events are the direct result of God’s constant intervention.

Much of the renewed interest in Atomism in the 16th and 17th Century was precipitated by scientific advances, particularly those of Nicolaus Copernicus (1473 - 1543) and Galileo Galilei (1564 - 1642), who himself converted to Atomism when he found that his corpuscular theory of matter and his experiments with falling bodies and inclined planes contradicted the mainstream Aristotelian theories. The English philosophers Sir Francis Bacon and Thomas Hobbes were both confirmed Atomists for a time, as was Giordano Bruno (1548 - 1600) in Italy.

However, the main figures in the rebirth of Atomism were the French philosophers René Descartes and Pierre Gassendi (1592 - 1655), and the Irish philosopher and scientist Robert Boyle (1627 - 1691).

Descartes’ mechanical philosophy of corpuscularism (that everything physical in the universe is made of tiny “corpuscles” of matter, and that sensations, such as taste or temperature, are caused by the shape and size of tiny pieces of matter) had much in common with Atomism, and may be considered in some sense another version of it, although for Descartes there could be no void, and all matter was constantly swirling to prevent a void as corpuscles moved through other matter. Descartes was also firm on the concept of mind/body duality, which allowed for an independent realm of existence for thought, soul and, most importantly, God.

Pierre Gassendi was a French priest and natural philosopher, who set out to “purify” Atomism from its heretical and atheistic philosophical conclusions. He formulated his atomistic conception of mechanical philosophy partly in response to Descartes, particularly opposing Descartes’ reductionist view that only purely mechanical explanations of physics are valid.

Robert Boyle's form of Atomism, which came to be accepted by most English scientists, was essentially an amalgamation of the two French systems. He arrived at it after encountering problems reconciling Aristotelian physics with his chemistry experimentation.

Roger Boscovich (1711 - 1787) provided the first general mathematical theory of Atomism, utilizing principles of Newtonian mechanics. Then, in the early 19th Century, John Dalton (1766 - 1844) developed his atomic theory in which he first proposed that each chemical element is composed of atoms of a single, unique type, which can combine to form more complex structures (chemical compounds).

Although philosophical Atomism led to the development of early scientific atomic theory, modern science has shown that atoms in the chemical sense are actually composed of smaller particles (electrons, neutrons and protons), and that these in turn are composed of even more fundamental particles called quarks. Although the principle can still theoretically apply, there are few, if any, modern-day atomists.

• Social Atomism is the belief that society should be viewed in terms of the individual's importance, and that society is artificially constructed. It holds that all properties of institutions and values merely accumulate from the striving of the individual.

• Logical Atomism was developed by Bertrand Russell (out of earlier work by Ludwig Wittgenstein) in an attempt to identify the "atoms of thought", the pieces of thought that cannot be divided into smaller pieces of thought.
• Simples Theory is a doctrine of contemporary mereology (the theory of parts and their respective wholes), where a "simple" is any thing that has no proper parts (similar to the philosophical concept of an atom), and is contrasted to "gunk" which is any whole whose parts all have further proper parts.