Kumārila （ca. 600-650） of the Mīmāṃsaka school argues in detail in his Ślokavārttika, especially the Nirālambanavāda chapter, against the Buddhist idealistic view that there is no external object apart from mind. After Kumārila, responding to his ciriticism becomes one of the major challenges for Buddhist idealists. Prajñākaragupta （ca. 750-810） is one of those who try to justify their Buddhist doctrine against Kumārila.
To the Buddhist idealists, who deny the existence of external objects, Kumārila says that, as long as the denial presupposes the “existence of external objects,” the idealists must also admit their existence. He also points out that if the existence of the external object is not known at all in the first place, then nobody would be able to understand whose non-existence is the subject.
In response to the above objection, Prajñākaragupta, by intentionally using the same logic as Kumārila, points out that the Mīmāṃsaka theory of bādhakapratyaya （or ‘sublating cognition’） also has the same problem. As with the external object for idealists, Mīmāṃsakas must also grant provisional existence to something to be sublated, since they claim that false cognitions will later be sublated by bādhakapratyaya. His point is this: in order to prove the non-existence of something, its “existence” must be assumed. However, this “existence” is only a provisional one, and the fact that one refers to it does not mean that one has admitted its existence in the actual sense.
