Within the Tibetan pramāṇa tradition, reasoning is treated as a precise discipline that supports both philosophical understanding and formal debate. At the broadest level, one finds a distinction between correct reasoning, faulty or fallacious reasoning, and doubtful or indeterminate reasoning. Correct reasoning is that which truly establishes its thesis, whereas faulty reasoning fails to do so, and doubtful reasoning leaves the matter undecided because it can be interpreted in more than one way. This threefold sensitivity to validity reflects a concern not only with what is asserted, but with how firmly and clearly it can be known.

A central feature of Tibetan logic is the analysis of what makes a reason “correct.” A proper logical sign must satisfy three modes: it must be present in the subject under discussion, it must be pervasively connected with the predicate to be proven, and it must be absent in clear counterexamples that lack that predicate. Debate training repeatedly returns to these three modes so that reasoning does not drift into mere verbal cleverness. When these conditions are met, one has what is called a correct reason, which serves as the backbone of syllogistic argumentation.

Within the domain of correct reasons, several specific types are distinguished, each illuminating a different way that thought can move from what is known to what is not yet known. Effect reasoning infers a cause from its observable effect, as when smoke is taken as a sign of fire. Nature reasoning proceeds from an essential or definitional connection, such as reasoning that whatever is produced is impermanent. Non-observation reasoning draws on the absence of perception where perception should occur, using that absence as a sign that the thing in question is not present. These three are not merely technical categories; they train the mind to notice different patterns of dependence and exclusion in experience.

Tibetan scholars also speak of reasoning in terms of its function in communication and debate. There is reasoning that is certain for oneself, grounded in one’s own clear understanding of the pervasion, and reasoning formulated specifically to convince others, framed in terms they already accept. In formal debate, this gives rise to two complementary styles: autonomous reasoning, where one directly establishes a thesis through general logical proof, and consequential reasoning, where one draws out the implications of an opponent’s position to reveal inconsistency. Together, these modes of reasoning cultivate a mind that is both rigorously analytical and skillful in guiding others toward insight.