Sarvadarshanasangraha 12.74

12.74

prāmāṇyaṃ parato jñāyate anabhyāsadaśāyāṃ sāṃśayikatvād aprāmāṇyavat/

"The argument, in my opinion, runs as follows:—Right knowledge depends on some cause[46] other than the common causes of knowledge, from the very fact that, while it is an effect, it is also knowledge, just as wrong knowledge does.[47] Authoritativeness is known through something external to itself [e.g., inference], because doubt arises in regard to it in an unfamiliar case, as we also see in non-authoritativeness.