 It is tarka that establishes a presumption against skepticism.  Gaṅgeśa (fourteenth century): “Were a person P, who has ascertained thoroughgoing positive correlations (F wherever G) and negative correlations (wherever no G, no F), to doubt that an effect might arise without a cause, then—to take up the example of smoke and fire—why should P, as he does, resort to fire for smoke (in the case, say, of a desire to get rid of mosquitoes)?  (Similarly) to food to allay hunger, and to speech to communicate to another person?” (Translation from Phillips 1995: 160–161, slightly modified.) The argument, which is found in the Nyāya-sūtra and other works (e.g., Vātsyāyana, preamble to Nyāya-sūtra 1.1.1), is that without the confidence that presupposes knowledge, we would not act as we do.