Indian logic (Nyaya) asks a different question from Western syllogism: not just "is this argument valid?" but "how do we know anything at all?" A pramana is a valid means of knowledge. The classical Nyaya list has four: pratyaksha (perception), anumana (inference), upamana (comparison) and shabda (verbal testimony). Later schools add arthapatti (postulation) and anupalabdhi (non-apprehension).
Worked example: A student sees dark clouds and infers rain. The inference has five parts: the paksha (the subject, here the sky), the sadhya (what is to be proved, rain), the hetu (the reason, dark clouds), the vyapti (the invariable rule, wherever there are such clouds, rain follows) and the example (a past case of clouds followed by rain). If the vyapti fails, the inference fails with it.