Kathavatthusutta 3.3

3.3

Sace panāyaṃ, bhikkhave, puggalo pañhaṃ puṭṭho samāno ṭhānāṭhāne saṇṭhāti parikappe saṇṭhāti aññātavāde saṇṭhāti paṭipadāya saṇṭhāti, evaṃ santāyaṃ, bhikkhave, puggalo kaccho hoti.

When an individual is asked a question, if they are consistent about what their position is and what it isn’t; about what they propose; about speaking from what they know; and about the appropriate procedure, then that individual is competent to hold a discussion.