Six Systems, Three Pairs

Classical Indian philosophy is not one thing, and it is not primarily Buddhism.

It organised itself into six orthodox systems, the darshanas: Nyaya, Vaisheshika, Samkhya, Yoga, Purva Mimamsa and Vedanta. Each has its own foundational text, its own line of commentators, and a position defended against the others in writing across roughly two thousand years.

Start with what orthodox means here, because it does not mean what an English reader expects.

It means accepting the authority of the Vedas as a source of knowledge. That is a claim about what counts as admissible evidence, not a claim about conclusions, and the six schools reach conclusions that contradict each other comprehensively. Samkhya is atheistic. Nyaya argues for a god. Both are orthodox, because the label describes what they are willing to cite.

The schools are traditionally studied in three pairs, and the pairing is the most useful thing to know about them.

Nyaya goes with Vaisheshika. Nyaya is the school of valid reasoning: what makes an inference good, what a fallacy is, how a debate should be conducted. Vaisheshika is the inventory: what kinds of thing there are, substances and qualities and motions and the rest. They are taught together because a logic needs an ontology to reason about, and an ontology needs a logic to defend it.

Samkhya goes with Yoga. Samkhya supplies a metaphysics, dividing everything into consciousness and the material principle. Yoga supplies the practice that follows from that metaphysics if it is true.

Purva Mimamsa goes with Vedanta. One is concerned with the interpretation of the Vedic texts as instructions for action, the other with the same texts as statements about ultimate reality.

In each case a method is joined to the thing it operates on, which is a better way to organise a curriculum than most.

But the fact that deserves the most attention is not the content. It is how the argument was conducted.

The convention was that you state your opponent's position first, at full strength, in their own terms, before you answer it. The technical name for that section of a text is the purvapaksha, the prior view, and a commentary that misrepresented its opponent was defective as a piece of work.

Two consequences follow, and both are remarkable.

The first is that a great deal of what we know about schools whose own texts did not survive comes from inside the books of their enemies. The obligation to state a position accurately turned refutation into a preservation mechanism, which is an unusually good accident.

The second is a standard. Stating the strongest version of a view you intend to demolish is difficult, slow, and against every instinct. That it was the expected form, for centuries, across schools that genuinely detested each other, is worth holding up against how argument is conducted now.

It is also worth noticing that this is the opposite of how these traditions are usually described in the West, where they tend to be presented as mystical rather than argumentative. The texts are dense, technical, and largely composed of people carefully taking each other apart.