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376 Speculations in the Medical Schools (CH. ad infinitum. These arguments in support of yukti as the concluding of the cause-effect relation from “this happening, that happens” relation are refuted by Santarakṣita and Kamalaśīla, who point out that there are no separate cognitive processes which link up the relation of “this happening, that happens” with the cause-effect relation, because both these convey the same concept. The causeeffect relation is the same as “this happening, that happens." It may be argued that, whenever anything invariably and unconditionally happens on the happening of any other thing, then the two are considered to be related as cause and effect, just as a jug, etc. are invariably seen to appear after the proper operations of the potter and his wheels. If this is yukti, then it is not a different source of knowledge.
Cakrapāņi, however, points out that these criticisms are all beside the point, since yukti, according to Caraka, is not kāryakāraṇatā from tad-bhāva-bhāvitā; it is the arriving at a conclusion as a result of a series of reasonings. But it is important to note that in 11. 4. 6 and 7 Caraka speaks of three kinds of pramānas, viz. pratyakşa, anumāna and sabda, and describes anumāna as being tarka depending on yukti. Tarka is explained by Cakrapāņi as being the knowledge of things which cannot be perceived (tarko 'pratyakşa-jñānam), and yukti is here paraphrased by Cakrapāņi as the relation of a-vinā-bhāva. It is said in this connection that a disease is to be determined by pratyakşa, the medical texts (āptopadeśa) and inference. But in 111. 8. 6. 33 and 34 Caraka counts aitihya as āptopadeśa, though ordinarily aitihya is considered in
1 drstānte 'py ata eva tad-bhāva-bhāvitvāt kāryatā-pratipattiḥ, tatrāpi drstānto 'nyo 'nveşanīyaḥ, tatrāpy apara ity anavasthā. Kamalaśila as quoted by Cakrapāņi on Caraka-samhitā, 1. II. 25.
Santarakşita misrepresents Caraka's view of yukti in a very strange manner. He says that, when from the fact that in all cases when A is present B is present and in all cases when A is absent B is also absent one thinks A to be the cause of B, this is regarded by Caraka as the new pramāņa of yukti. Sántaraksita's exact words are:
asmin sati bhavaty eva na bhavaty asatīti ca tasmād ato bhavaty eva yuktir eşā 'bhidhiyate pramānāntaram eveyam ity äha carako munih nānumānam iyam yasmād drşțānto 'tra na labhyate.
Tattva-samgraha, p. 482. This, however, is entirely different from what Caraka says, as is pointed out by Cakrapāņi in his commentary on Caraka-samhita. Caraka's idea of yukti is the logic of probability, i.e. when from a number of events, circumstances, or observations one comes to regard a particular judgment as probable, it is called yukti, and, as it is different from inference or any of the other accepted pramānas, it is to be counted as a separate pramāņa. So far as I know, this is the only example of the introduction of the logic of probability in Indian thought.
