Are there simple beings?
As was noted on the previous page, Vasubandhu describes substantial beings as those things that cannot be broken into smaller physical pieces and cannot be analyzed by the mind into more basic ideas. The first of those two criteria, the physical one, would naturally lead to some notion of atomicity, an atom being an ultimately tiny particle of matter that cannot be physically divided into anything smaller. The fact that Vasubandhu gives water as an example of a substantial being suggests that he probably had water atoms in mind, water being one of the four basic elements that Indians in his day recognized as a basic building block of the physical world. It is probable that he had water atoms in mind, rather than, say, a body of water contained in a lake or a clay pot, because a macroscopic body of water can easily be physically divided.
The very idea of an atom, however, gives rise to several problems, all of which were recognized by numerous philosophers of various schools of thought in India. First, it was recognized that anything that has more than zero dimension can be divided, at least in principle if not in actual practice, into at least two smaller parts. Only something that takes up no space at all is immune from having its space subdivided into compartments. It is difficult, however, to explain how something that takes up no space at all could be a building block for something that does takes up space. No matter how large a number is multiplied by zero, the product will always still be zero. Moreover, in most Buddhist treatises a substance is defined as that which has resistance, that is, that which occupies a space and resists any other thing occupying that same space at the same time. If something occupies zero space, then how can it be regarded as having the sort of resistance that defines it as a substance? Because of these problems, many Buddhists (including Vasubandhu himself later in his career) rejected the reality of atoms. At best, said the critics of atomicity, an atom could be seen as an idea to which there could not possibly correspond anything in the physical world. More about this will be said below.
There is another way of thinking about Vasubandhu’s example of water as an unbreakable substance. It could be that rather than thinking of the elements (earth, water, fire, air and space) as atomic particles, they can be seen as irreducible properties of matter. Earth, for example, might be seen as the principle of support, water as cohesion, fire as transformation and air as motion. In fact, when Indian Buddhist scholastics discussed the elements, there was a tendency to describe them in just that way. One could even think of the elements as representing something like what physicists call the states of matter, so that earth stands for any substance in its solid state, water for any substance in its liquid state, air for any substance in its gaseous state, and fire as something like energy. A possible concern about thinking of the elements in this way is that one never actually encounters any of these principles alone and in their pure form. If one experiences, for example, a clay pot, one is encountering the principles of support and cohesion inextricably mixed together. No physical object can exist without some temperature, and that is represented by the element fire. The elements, thought about in this way, are really more like abstractions that elements of experience. That being the case, their being simple or irreducible must something more in the way that an idea is irreducible, rather than the way in which a particle of matter might be irreducible.
The second of the two criteria of a substantial being that Vasubandhu mentions is that it cannot be analyzed by the mind into more basic ideas. Intuitively, this criterion would seem to be picking out something like a primitive idea, an idea that cannot be reduced to other ideas but that can serve as a component of a more complex idea. Empirical philosophers in Europe, such thinkers as David Hume and John Locke, argued that the idea of, say, a dog is a complex idea, since it can be broken down into more simple ideas such as a head, a tail, a growl, and a bark; similarly, a head is a more complex idea than the simpler ideas of a snout, eyebrows and ears. The ultimately simple ideas for such thinkers would presumably be those that are derived from direct sensation. There is a Buddhist counterpart to this sort of thinking. For many Indian Buddhist scholastics, the most fundamental components of experience are various kinds of sense data, such as particular colors, shapes, odors, sounds, tastes and tactile properties such as pressure and temperature. The idea of a dog is a complex notion that arises when there is a sensation of some combination of a particular shape, a distinct aroma, a specific sound and a special texture.
While it is may seem unproblematic to say that the idea of a dog is more complex that the idea of a tooth and that the idea of a tooth is more complex than the idea of the color white and the texture hard, the question is whether there is any such thing as an ultimately simple idea, and unanalyzable given. To this question a follower of Nāgārjuna would give a negative answer. Every idea is intelligible only in a context of cluster of similar but somehow contrasting ideas. The notions of whole an.d part or hard and soft, for example, are intertwined in such a way that neither notion can be understood without reference to the other. The claim is that a notion that cannot be understood without reference to another is in some sense complex, or at least derivative and not primitive.