Catuṣkoṭi

Catuṣkoṭi (Sanskrit; Devanagari: चतुष्कोटि, Tibetan: མུ་བཞི, Wylie: mu bzhi, Sinhalese:චතුස්කෝටිකය) refers to logical argument(s) of a 'suite of four discrete functions' or 'an indivisible quaternity' that has multiple applications and has been important in the Indian logic and the Buddhist logico-epistemological traditions, particularly those of the Madhyamaka school.

In particular, the catuṣkoṭi is a "four-cornered" system of argumentation that involves the systematic examination of each of the 4 possibilities of a proposition, P:

1. P; that is being.
2. not P; that is not being.
3. P and not P; that is being and that is not being.
4. not (P or not P); that is neither not being nor is that being.

These four statements hold the following properties: (1) each alternative is mutually exclusive (that is, one of, but no more than one of, the four statements is true) and (2) that all the alternatives are together exhaustive (that is, at least one of them must necessarily be true). This system of logic not only provides a novel method of classifying propositions into logical alternatives, but also because it does so in such a manner that the alternatives are not dependent on the number of truth-values assumed in the system of logic.

An example of a Catuṣkoṭi using the arbitrary proposition, "Animals understand love" as P would be:

1. Animals understand love
2. Animals do not understand love
3. Animals both do and do not understand love
4. Animals neither do nor do not understand love