Translating ‘apadesa’ is difficult. The PED says it means “reason, cause, argument”. But no one calls cattāro mahāpadesā “the four great reasons/ causes/ arguments”. They call them the “four great references” or “four great criteria” or “four great standards” or “four great authorities”. I choose “four great endorsements” because it is the opposite of what one might call “the four great rejections”. As the sutta makes clear, one either rejects or endorses a statement a monk makes by the conclusion one comes to about it. If one concludes that it is not the word of the Buddha, that conclusion is a rejection. If one concludes that it is the word of the Buddha, that conclusion is an endorsement.
The Buddha said that if a monk claims what he heard from some authoritative source is Dhamma or Vinaya or the Teacher's instruction, his words should be compared with the suttas and with Vinaya. If his words do not accord with these, one can conclude that they are not the word of the Sublime One (bhagavato vacanaṃ). Therefore they should be rejected (chaḍḍheyyātha). (The Anguttara Nikaya is slightly different: it calls it, not the “word of the Sublime One” but “the word of the Sublime One, the Arahant, the perfectly and completely Awakened One”: bhagavato vacanaṃ arahato sammāsambuddhassa).
The “word of the Sublime One” must include the recorded words of his disciples, because these words are also included in the suttas and Vinaya. Venerable Uttara says that "whatever is well-spoken, all that is the word of the Sublime One, the Arahant, the perfectly and completely Awakened One. Wholly derived from that is what we and others say" (yaṃ kiñci subhāsitaṃ sabbaṃ taṃ tassa bhagavato vacanaṃ arahato sammāsambuddhassa, tato upādāyupādāya mayañcaññe ca bhaṇāmāti) ( A.4.164).
If the monk’s words accord with what is found in the suttas and Vinaya, instead of rejecting them, one comes to a positive conclusion about them. Because there are four authoritative sources, there are therefore four great endorsements, which the suttas explain as follows:
“A monk might say that:
In each case, the monk’s claim should be neither applauded nor scorned. Instead, every word and sentence he speaks should be carefully studied (tāni padabyañjanāni sādhukaṃ uggahetvā) and compared with the suttas and with Vinaya (sutte otāretabbāni vinaye sandassetabbāni).
If when so compared they do not harmonise with the suttas and vinaya, then one can conclude (niṭṭhamettha gantabbaṃ) “This is certainly not the word of the Blessed One. It has been wrongly taken (duggahitanti) by that monk [the messenger himself]/ that Sangha of monks/ those many senior monks/ that senior monk”. Therefore one should reject what the [messenger] monk says (chaḍḍheyyātha).
But if the monk’s words harmonise with the suttas and vinaya, then one can conclude (niṭṭhamettha gantabbaṃ): “This is certainly the word of the Sublime One. It has been correctly taken (suggahitanti) by that monk/ that Sangha of monks/ those many senior monks/ that senior monk”.
The Buddha said that these four conclusions “should be remembered (dhāreyyātha) as being:
“These are the four great endorsements”: ime kho bhikkhave cattāro mahāpadesāti.
(D.2.124; A.2.168).
