 There is also “hypothetical reasoning,” tarka, which, although not itself a knowledge source, is said to be able to shift the balance of what it is rational to accept. Its main role is to help people grasp pervasions, and is an important supplement to the inferences that are central to philosophic controversies. Gaṅgeśa explains tarka as a hypothetical argument revealing a fallacy or defeater with respect to a position ∼p opposed to another position p that is to be accepted so long as p has independent evidence in its favor, technically called, pratikūla-tarka. There is, however, also anukūla-tarka, “supportive reasoning,” such as economy of conception, that is positive in character. The types of tarka that Gaṅgeśa recognizes are: (1) ātmâśraya, “self-dependence” (begging the question), (2) anyonyâśraya, “mutual dependence” (mutual presupposition), (3) cakraka, “circularity” (reasoning in a circle), (4) anavasthā “infinite regress,” (5) aniṣṭa-prasaṅga, “unwanted consequence” (contradiction), (6) prathama-upasthitatva, “being presupposed by the other,” the “first established” (a form of anukūla, “favorable,” tarka), (7) utsarga, “hasty generalization,” (8) vinigamanā-viraha, “differentiation failure,” (9) lāghava, “economy of conception,” “theoretic lightness” (another form of favorable tarka), and (10) gaurava, “lack of economy of conception,” “theoretic heaviness” (Bagchi 1951: 151).