Synopsis The Vaidalyaprakarana belongs to the Madhyamika school of Buddhist Philosophy. It demonstrates the logical impossibility of the existence of the Nyaya categories or padarthas as enumerated and dealt with in Gautama’s Nyayasutra and Vatsyayana’s Bhasya thereof. It belongs to the Indian philosophical tradition which did not admit the pramanas as valid means of knowledge. The Vaidalyaprakarana is immersed in the dialectical atmosphere that characterizes that tradition, although its aim is to show the groundlessness of Dialectics. The treatise gives a clear idea of the Madhyamika conceptioin of logic. It deals with many themes of Indian Philosophy. The present book contains an Introduction in which the authorship of the Vaidalyaprakarana is discussed, reaching the conclusion that, although the facts analysed by the authors “may not undoubtedly discard the authorship of Nagarjuna, at least they provoke a doubt regarding it – a doubt that is stronger in regard to the commentary”. It also contains the edition of the Tibetan text on the basis of the Sde-dge, Cone, Peking and Snarthan editions, an English translation and a commentary by the authors, on the doctrinary contents of the treatise, and finally notes giving parallel pertinent texts.