Beyond true or false: the ancient logic of the four-cornered argument

Ideas & Philosophy · Published 18 October 2026 Swipe more like this →

In short: Most Western logic relies on a binary: something is either true or false. But ancient Indian traditions developed the Catuṣkoṭi, a sophisticated four-cornered system designed to exhaust every logical possibility, including the paradoxical and the neither-nor, to reveal a deeper reality.

The Catuṣ’, or 'four-cornered' system, functions as an indivisible quaternity of logical possibilities. For any proposition P, the system examines four discrete functions: P is true; P is not true; both P and not P are true; and neither P nor not P is true. These four alternatives are both mutually exclusive and collectively exhaustive, meaning that while only one can be true, together they cover all possible logical ground.

While often associated with the Mādhyamaka school of Buddhism, the Catuṣkoṭi likely originated in an earlier Indian sceptical tradition. Its structure bears striking similarities to the Greek Pyrrhonism, suggesting a possible shared influence from early Indian scepticism. The method was famously refined by the philosopher Nagarjuna. He used these arguments as a 'learning, investigative, meditative' portal to realize Śūnyatā, or 'openness.' By using double refutations—denying both the presence and absence of a subject—Nagarjuna sought to demonstrate the irrationality of existence-based reasoning.

The system's application can vary significantly. Some scholars suggest the four statements can be applied as a 'suite' to form a paradoxical matrix, while others suggest they function like 'trains running on tracks,' where only specific functions are used at particular times. Beyond pure logic, the Catuṣkoṭi is viewed by some as a tool to dispel the 'spell' of reality—the unconscious tendency to take certain perceptions as inherently real by ignoring their necessary backgrounds.

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