Nāgārjuna's Four Corners and the Argument From None of the Above

Nāgārjuna, writing in southern India around 150 CE, inherited a Buddhist debating device called the catuṣkoṭi — "four corners." Faced with any question of the form "is X the case?", you could answer in four ways: yes, no, both yes and no, neither yes nor no. Earlier Buddhist texts use it as a sorting tool. Nāgārjuna does something stranger. He denies every corner.

Take the question of whether the self is the same as the body. Same? No. Different? No. Both same and different? No. Neither? Also no. The Mūlamadhyamakakārikā runs this play across causation, motion, time, the Buddha himself. Each time the four corners get knocked down, and the conclusion is not a fifth answer but the dissolution of the question.

The positive claim hiding inside the negative one is śūnyatā — emptiness. If "the self is the same as the body" can't be coherently affirmed or denied or both or neither, then there is no determinate fact for the proposition to track. The categories the question depends on lack independent essence; they exist only as dependent designations, propped up by other dependent designations. Knock them out together and the whole web collapses gracefully.

Western logicians have spent the last century arguing about whether this is paraconsistent logic, equivocation, or a non-classical negation that distinguishes denying a property from asserting its absence. Graham Priest, who reads it as a serious formal system, calls the rejection of all four corners a "fifth corner" Nāgārjuna was happy to occupy.

The pedagogical effect is the harder thing to translate. The four-corners move was meant to leave the listener with no foothold — and for Madhyamaka, no foothold is the point.