Catuskoti

Catuskoti, also known as the tetralemma, is a classical logical device in Indian and Tibetan Buddhist philosophy. It presents four alternative positions regarding any proposition about phenomena or dharma: it exists, it does not exist, it both exists and does not exist, or it neither exists nor does not exist. The fourfold scheme is intended as a method for testing and refining concepts rather than as a simple ontological rule.

Origins and development: The tetralemma appears in early Buddhist literature and was developed within the Indian Buddhist logico-philosophical tradition, most prominently associated with the Madhyamaka school as taught by Nagarjuna. It was later taken up and elaborated by Tibetan scholars and other Buddhist traditions. The exact formulation and emphasis vary among sources, with some versions using different expressions for the fourth alternative.

Purpose and use: The catuskoti is used to challenge whether ordinary predicates can capture the true nature of reality. In Madhyamaka, it serves to reveal the emptiness (shunyata) of inherently existing phenomena and to prevent reification of views about ultimate truth. By presenting all four logical options and showing their inadequacy, the method aims to redirect analysis toward dependent origination and the limits of language.

Variations and reception: There is variation in how the four alternatives are framed across schools. Some interpret the fourth option as “neither true nor false” or as “both true and false,” while others emphasize its role as an elastic, diagnostic tool rather than a fixed doctrine. The catuskoti has influenced both Buddhist logic and meditation on the nature of reality, and it remains a notable feature of traditional Buddhist epistemology.