In the comments, dwc points me to a student of Balu, Jakob de Roover, on the absence of the supernatural in the Indian traditions, who points us to Dale B. Martin in Inventing Superstition: from the Hippocratics to the Christians (Harvard University Press, 2004).
“One of the basic arguments of this book is that, contrary to many modern assumptions, the category of “the supernatural” did not exist in ancient culture as a category. Neither popular notions, held by the vast majority of inhabitants of the ancient world, nor philosophical notions (we could say “scientific” with due consideration for the possible anachronistic connotations of the term) assumed that reality was split up into two realms, one “natural,” containing things like “matter” and “natural forces” such as gravity or electricity, and another “supernatural,” to which gods and similar beings (demigods, angels, demons, ghosts) could be assigned…
What is important for this post is that the category was not available, either explicitly or by assumption, for persons in the classical Greek and Roman worlds. The Greeks and Romans certainly had no word that was equivalent to the modern English “supernatural.”
…I do not, however, want just to quibble about words. Classical Greeks and Latin had not term for what passes in the modern world as “the supernatural” precisely because the ancients did not separate out divine forces and beings from “nature” and relegate them to a separate ontological realm that could designated by its own label. Generally, for ancient people whatever does exist exists in “nature.” Almost without exception the Greek term physis (nature) refers to “all that is.”
People might argue that the gods did not exist or that some particular daimon or god or superhuman being did not exist (I know of no ancient author who argued for actual atheism in the modern sense). But in that case, they said that the disputed entity simply did not exist, not that it might exist in some other realm of reality, such as the “supernatural.” Ancient philosophers might argue that lightning was not caused by a god, but they did not do so by pointing out that lightning occurs in the “natural” realm and that the gods exist in the “supernatural” realm and that the two realms are not supposed to interact with one another. Ancient people took the gods and all other beings we would think of as “supernatural” to be part of nature if they existed at all.” (pp. 13-15)
Jakob then makes the similar argument for the Indian traditions. What is important for what follows is this observation.
Now, suppose one advances a theory that religion has something or other to do with the supernatural, (and atheism has to do with the denial of the supernatural, as PZ Myers, Richard Dawkins, and internet atheists often aver). Unless one shows that the division of the world into the "natural" and "supernatural" is meaningful outside of Christian theology, one's theory of religion implicitly accepts the truth of Christian theology.The term ‘supernatural’ – as Dale Martin makes it very clear – does not make sense without assuming the division of the world into two ontologically separate realms. This division is central to the Christian theological view of the world: there is the eternal, spiritual, supernatural realm as opposed to the temporal, material, natural realm.
Natural is "existing in or formed by nature". The supernatural "pertains to, or is above or beyond what is natural". One can ask whether concepts from failed/lapsed scientific theories are natural or supernatural. We commonly don't consider phlogiston, the luminiferous ether, action at a distance, and so on to be supernatural, though they don't exist in nature, and are ruled out by the laws of nature. Natural == "could plausibly exist in nature" does not fix the problem, because plausibility depends on the observer.
Is the Platonic world of ideal mathematical objects natural or supernatural? It doesn't exist in nature. Euclid's plane exists only in our imagination, though it is a description we all can share and agree on.
Is the wave function in quantum mechanics natural or supernatural? The wave function is a description, the most complete description of a physical situation that is possible; yet we run into problems if we insist that the wave function exists as a physical object. In particular, before an instantaneous measurement of position, the wave function is an extended thing, and after the measurement it is collapsed to a point. Other laws of physics tell us that such an entity cannot exist as a physical object. But if the wave function does not exist in nature, is it supernatural?
Would it be acceptable for an ancient Indian brought to modern times to have doubts like I mentioned above?
Since we ordinarily do not have these type of doubts, it is because we all blindly accept the ontology that Christianity has given us. The usage of "natural" and "supernatural" tells us more about our current culture than it does of the cultures of the ancient Greeks, Romans, Indians. Because we do not have the kinds of doubts I expressed, it is clear that "natural" and "supernatural" go beyond word definitions, but are concepts in a theory (Christian theology) that we have internalized.
While one may not accept these arguments, I hope I have awakened the reader to the possibility that the current description of other cultures - a part of the social sciences - is parasitic on Christianity and in that sense may not be science at all.