Atomic Theory in Indian Philosophy

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In classical Indian philosophy two Sanskrit words are used for the atom, the smallest impartite physical entity: "au" and "paramāu." On the existence of such atoms, the classical Indian philosophers were divided. Among the orthodox Brahmanic schools, the Nyāya-Vaiśeika philosophers were the preeminent defenders of atomism, with the Mīmāsā philosophers as allies. On the opposite side, the Vedāntins denied atomism. Among the non-Brahmanic schools, the Jainas were clearly atomists, as were the Hinayana Buddhists. Yogācāra Buddhism, however, was strongly critical of atomism, and so too was Madhyamaka Buddhism.

The division of opinion on the issue thus cuts across the division between the Brahmanic and non-Brahmanic schools. Instead, the range of views about atomism more closely reflects the different schools' commitment to realism. After all, atomism is usually associated with a realist view of the world, in which atoms are taken to be objective, mind-independent entities. Predictably enough, then, we find espousing atomism such staunch philosophical realists as the Naiyāyikas and Mīmāsakas, as well as such heterodox realists as the Ābhidharmikas and the Jainas. In contrast, opposition to atomism is led by such antirealists as the Advaitins, the Mādhyamikas, and the Yogācārins.


The earliest Indian defenders of atomism may well be the Jainas, with texts defending atomism that date at least as far back as the third century CE. According to Jainism, everything in the world, save for souls and space, is produced from matter, and all matter consists of indivisible atoms (paramāu ), each occupying a single point of space. Matter has two forms: a simple or atomic form and a compound (skandha ) form. Perceivable material objects are compounds, composed of homogeneous atoms (there are no distinct kinds of atoms corresponding to the four kinds of elements). Impartite atoms are eternal, though this is obviously not true of the partite compounds. Indeed, atoms are supposed to be eternal precisely because they lack parts and are thus incapable of disintegration. But there is nonetheless a sense in which atoms, like compounds, are subject to qualitative change because, though all atoms are indistinguishable in substance, qualities present in an atom can be increased or decreased by many degrees.

To explain how atoms join as they do, the Jainas posit that some atoms are viscid and some dry, which permits aggregation of the two different kinds of atoms (much as particles of barley meal combine to form lumps when drops of water fall upon them). Moreover, they are viscid and dry in various degrees, with no aggregates combining atoms with the lowest degrees of the two properties or equal degrees of the same property.

These Jaina speculations help to highlight three central questions for which the Indian philosophers expected atomic theories to provide answers: What evidence do we have for the existence of atoms? How is it possible for one atom to join with another? Why do atoms come together as they do?

With regard to the first question, the two main Indian arguments for the existence of atoms are both inferential. The first argument rests on the claim that there has to be a lower limit to the scale of diminishing minuteness. Gross objects clearly exist and are divisible. Yet the process of physical division must have a terminal point, and this terminal point to division must, by definition, be indivisible. The second argument attempts a reductio ad absurdum of the denial of such a terminal point: Unless the process of division comes to an end, everything must be equally composed of an infinite number of parts, and hence all comparative ascriptions of unequal magnitude to gross objects are undermined. The mountain and the mustard seed would have to be of equal size!

Of course, even if we are persuaded by these arguments that atoms do exist, any atomic theory still needs to address the second question and offer some explanation of how atoms combine to form partite entities. After all, atoms are supposedly impartite, and yet our only direct experience of conjunction involves partite things. But if we give up the thesis that atoms are truly impartite, we also have to give up one of the main arguments for the existence of atoms.

In reply, the Naiyāyikas utilize their distinctive mereological theory (theory of partition), according to which composite wholes are never reducible to their parts, though wholes inhere in parts. Hence a composite whole is a distinct entity, and not a mere collection of its conjoined parts. Moreover, since the whole is thus distinct from the sum of its parts, it can, unsurprisingly, have properties not possessed by any of its parts. This particular mereological theory, however, is unacceptable to both Buddhists and Advaitins, who object that the idea that wholes inhere in their parts would require a further relation to relate inherence to its relata, and so on ad infinitum. The Buddhists maintain instead that wholes are unreal, being mere conceptual constructions, and only parts are real. Thus for them, all conventional objects are mere aggregates of atoms. The Jaina response is different again: The composite whole is just the parts in a changed state.

Finally, even if we have reason to believe both that there are atoms and that they can combine, a viable atomic theory still needs to offer some sort of explanation of how atoms are brought together. The Jaina explanation in terms of a theory of varying degrees of viscidity and dryness builds on their view that all atoms are homogeneous, with the result that the division into the four elements is derived and secondary. The Nyāya-Vaiśeika school denies this, claiming instead that the four elements of earth, water, air, and fire involve four kinds of atoms sufficiently qualitatively different from each other so that the atoms of one element can give rise only to products of that element.

The elaborate Nyāya-Vaiśeika theory of how atoms combine to form compound entities seeks to address the issue of how atoms of infinitesimal magnitude can add together to produce a macroscopic object. Their explanation is that when two infinitesimal atoms combine into a dyad, there is a sort of quantum leap, and the new submolecule thus formed has a minute (hrasva ) magnitude. Dyads then combine into perceptible molecules or triads (composed of three dyads), and there is another quantum leap in magnitude to a gross (mahat ) quantum. The addition of gross quanta then straightforwardly accounts for the magnitude of macroscopic objects.

The point of this postulated double quantum jump from single atoms to dyads and then from dyads to triads is to insist that the finite magnitude of the triad arises from the infinitesimal atoms as a result of the number of the constituent atoms and not as a result of their magnitude, as in gross objects. Unsurprisingly, many Indian philosophers (both atomist and antiatomist) found this part of the Nyāya-Vaiśeika atomic theory unconvincing.

Moreover, all of this still leaves unexplained the initial conjunction of two atoms to produce a dyad. Later the Nyāya-Vaiśeika school invoked God's agency to help out here: Since all atoms are insentient, the process of combination must be guided by an intelligent divine agent. Other Indian philosophers disagreed, however, as to whether this amounts to a persuasive argument for the existence of God or to just an ad hoc addition to an already unsatisfactory atomic theory.

The Nyāya-Vaiśeika school took one advantage of its atomic theory to be that it can avoid the Buddhist theory of universal flux and can explain the identity of a substance through change in terms of the identity of unchanging, eternal atoms. A substance can undergo change without the constituent atoms changing because the qualities of a substance can change while the substance persists. However, consider what happens when we fire a clay pot so that it changes color. The Vaiśeikas claimed both that the unfired pot as a whole is replaced by a new pot as a whole, and that the application of heat causes a change of qualities to occur at the level of the individual atoms. But in admitting that change at the level of gross objects involves change at the atomic level, the Vaiśeika theory risks collapsing into the Buddhist theory of universal flux. Hence the Nyāya atomic theorists denied that change occurs at the level of the individual atoms, claiming instead that the whole remains intact while the change occurs.

Common to the different atomic theories of both Jainism and Nyāya-Vaiśeika are the claims that the atoms are genuinely indivisible, infinitesimal, and eternal. Other Indian atomists deny some of these claims. The Mīmāsā school, for instance, is willing to admit that whether entities are gross or minute is only relative. They thus accept as atoms the dust motes visible in a sunbeam (these are triads in the Nyāya-Vaiśeika system, the smallest perceivable particles). Although the Mīmāsakas do not entirely rule out the Nyāya-Vaiśeika conception of an atom as impossible, they criticize it as an overly speculative thesis. Even if the dust mote is theoretically divisible and hence apparently nonatomic, Mīmāsakas are only willing to accept such atoms as are established by common experience. There is no purpose served by assuming any atoms beyond these.

In contrast, the Ābhidharmika atomists affirm the existence of atoms smaller than dust motes but deny that they are eternal, since in Buddhism everything is taken to be impermanent. According to Buddhist atomic theory, although atoms are the smallest unit of matter, they never occur alone, but rather occur only as members of an aggregate of at least seven or eight atoms. Hence it is unsurprising that we do not experience individual atoms as separately perceptible. But we do nevertheless perceive the aggregates and, contrary to Nyāya-Vaiśeika claims, there are no aggregates distinct from the atoms themselves. Thus our perception that the atoms constituting an aggregate are gross is really an illusion due to the close and collective presence of a multitude of minute atoms.


The Vedāntins and the Mahayana Buddhists were the chief representatives of Indian antiatomism, though their objections to atomism are frequently different and their own rival ontologies are significantly distinct. One specifically Vedāntin argument against atomism is that the Hindu scriptures nowhere affirm it. Clearly, this argument is not intended to persuade non-Brahmanic atomists, but it is interesting to note that most Brahmanic atomists too do not feel obliged to respond to it. The mere absence of a Vedic sanction is apparently thought to be obviously insufficient grounds for rejecting a philosophical theory. (A notable exception to this general trend of indifference is the Naiyāyika philosopher Udayana [eleventh century, CE], who goes out of his way to argue that there is indeed a scriptural warrant for atomism.)

The Advaita Vedāntins offered a more straightforwardly philosophical objection to the Nyāya-Vaiśeika theory of atomic composition. They argued that ontological parsimony ought to make us reject the Naiyāyikas' posit of dyads as unnecessary, for why can we not just say instead that three atoms directly combine to form a triad, the smallest visible substance. The gross magnitude of the triad will then be explicable not in terms of the magnitude or aggregation of atoms, but in terms of the number of atoms.

The main Indian argument that some form of atomism is rationally necessary is, of course, that it is required to explain the existence of gross material objects, which are indisputably partite. Again and again the atomists defended the controversial details of their theories with an argument to the best explanation: that since all agree that there are composite physical objects, one needs to posit atoms to best explain their existence and nature. But this strategy presupposes a common commitment to realism about the external world. The Indian antiatomists did not share this general commitment.

This is particularly obvious when we attend to the antiatomist arguments of the Yogācārin philosopher Vasubandhu (fourth or fifth century CE). Vasubandhu began by explicitly affirming the idealist thesis that everything is mind only. But realism, of course, denies this thesis. Vasubandhu responded by arguing that realism is false because realism implies atomism and atomism is incoherent.

Like the Ābhidharmikas, Vasubandhu rejected the Nyāya-Vaiśeika theory of organic wholes as unsupported by experience. But he also rejected the Abhidharma view that material wholes are mere aggregates of atoms, on the ground that for this to be so, the atoms would have to be joined. Such conjunction is either partial or total. If it is partial, the atoms must have parts in contact with one another; if it is total, all the atoms must collapse into the same atom-sized space. Either way, there cannot be a plurality of impartite atoms. Furthermore, an atom cannot be thought of as spatially extended without allowing that it has a front part different from its back part. But if atoms are unextended, then aggregates of them cannot constitute extended gross objects. Thus atomism (and hence realism) is incoherent, and idealism is vindicated.

Yogācāra Buddhism is admittedly a rather peculiar kind of idealism, since it denies the existence of both the objects of consciousness and the subject of consciousness. Ultimately, all that exists is pure consciousness devoid of all subject/object duality. But whether or not Yogācāra thought is best classified as a variety of idealism, it is indubitably a variety of antirealism. Moreover, while other Indian antiatomists, such as the Mādhyamikas and the Advaitins, were certainly not idealists, they also in their various ways shared the Yogācāra thinkers' antirealist doubt of the commonsense assumption of an objective reality populated by ontologically independent entities. These Indian antiatomists are thus all equally unforgiving of the atomists' general strategy of attempting to excuse the anomalies in their various atomic theories by an appeal to atomism as the best explanation of gross external objects. In classical Indian philosophy, the avowed aim of philosophy is liberation (moka ). For the Indian antirealists, this goal is to be attained not by theorizing about the nature of a supposedly objective external world, but by transcending all such conceptions, including atomism and its presuppositions. In this sense, there is arguably a common antirealist motivation for Indian antiatomism, notwithstanding the very significant philosophical differences among the different antiatomist schools.

See also Causation in Indian Philosophy.


Gangopadhyaya, Mrinalkanti. Indian Atomism: History and Sources. Calcutta, India: K. P. Bagchi, 1980. A splendid anthology of Sanskrit primary sources together with annotated English translations. Also contains a very useful historical introduction.

Kapstein, Matthew T. Reason's Traces. Boston: Wisdom, 2001. Chapter 7 is an excellent philosophical study of Vasubandhu's arguments against atomism.

Potter, Karl H., ed. Indian Metaphysics and Epistemology: The Tradition of Nyāya-Vaiśeika up to Gageśa. Princeton, NJ: Princeton University Press, 1977. An extremely valuable survey of early Nyāya-Vaiśeika metaphysics.

Roy W. Perrett (2005)