How to Determine Whether Someone Has Attained Enlightenment in Buddhist Practice

In the worldly realm, to serve as a judge, one must possess thorough knowledge and understanding of the subject matter being judged; that is, one must be an expert. For example, to evaluate the teaching proficiency of a university professor, one's own level of knowledge must be higher than or at least equivalent to that professor. To assess the quality of an undergraduate student's thesis, one must be a university faculty member. In the practice and realization of the Dharma, to determine whether someone has attained enlightenment or seen their true nature, one must first be a person who has realized the mind and seen the true nature oneself. Only by having walked that path and become familiar with it can one know whether the path others are taking is correct, and also discern where others stand along that path. Regarding the discernment of the Dharma, the minimum requirement is to possess the eye of discriminative wisdom (dharma-prajñā). It is best to have few doubts about the essential Dharma; even better is to have attained that Dharma oneself, for only then can one make relatively accurate judgments. However, those who have cultivated to such a level are few. To judge whether others have attained the fruits of enlightenment, one must first have attained the fruits oneself. Only upon attaining the first fruit (Sotāpanna) can one eliminate doubt—no doubt about whether one has attained the fruit oneself, no doubt about whether one's teacher has attained the fruit, and no doubt about whether the Dharma can enable sentient beings to eradicate the view of self and ego-clinging. Otherwise, one cannot judge others. When one lacks a scale oneself, it is impossible to measure other things.