In judging the relative merit of Buddhist doctrines, I, Nichiren, believe that the best standards are those of reason and documentary proof. And even more valuable than reason and documentary proof is the proof of actual fact.WND I: 68, p 598
Documentary proof, theoretical proof, and actual proof are the three standards set forth by Nichiren for judging the validity of a given teaching. Documentary proof means that the doctrine of a particular Buddhist school is based upon or in accord with the sutras. Theoretical proof means that a doctrine is compatible with reason and logic. Actual proof means that the content of a doctrine is borne out by actual result when put into practice.
Mr. Makiguchi explained the three kinds of proof in an accessible manner, comparing them to the three criteria for choosing a physician. In this instance, considering the physician’s academic history, title and medical specialty is equivalent to documentary proof. Actual proof, meanwhile, is whether the physician has successfully treated many patients, which is an even more important criterion. Moreover, theoretical proof, or proof by reason, is whether the physician’s methods are reasonable from the perspective of the science of medicine. If you are satisfied with this aspect of the physician’s qualifications, then you will have no worries. 27
Mr. Makiguchi went on to stress that proof by actual fact is most important, and that both our lives and our efforts at value creation should be based on it. 28
Mr. Toda, meanwhile, asserted that “the correct evaluation of actual proof is that it agrees with documentary proof and theoretical proof, and can be demonstrated in actual life.” 29 Any occurrence in the realm of Buddhism, if not borne out by documentary or theoretical proof, is nothing more than coincidence or a strained interpretation of the facts.
The three proofs are the criteria for judging whether a teaching enables us to create value in our daily lives and to create happiness and peace for all people.