1. Certainty. When, in logic, an argument is valid, the conclusion is said to be certain, e.g., if A = B and B = bitumen, then A = bitumen. The certainty consists, however, only in the validity of the argument that yields this conclusion; it does not by any means insure the truth of either the premise A = B or the premise B = bitumen. Such is mathematical certainty, c.g., if 2 + 2 = 4, then 4 - 2 = 2. One can never attain that kind of certainty concerning a proposition such as "Planet Earth will continue in its customary orbit tonight," even though the probability is overwhelmingly great; nor can one be certain in that way that no pigs can fly, although a flying species of pig would astonish everyone. The impossibility of certain knowledge other than the deductive kind indicated above has imphcations of the most fundamental kind in the philosophy of religion, not least in arguments for or against the existence of God. We may nevertheless have psychological certainty (some philosophers have preferred the name "certitude" for this) about many things. Believers and unbelievers alike may claim such certitude on the question of the existence of God, claiming that the view they respectively take is subjectively certain for them, being moreover confirmed in the experience of their lives. Such affirmations as they make on the basis of such "certitude" may be supported by various kinds of argument, although these cannot be expected to yield certainty such as is to be found in the proposition that the internal angles of a triangle = 180°. See God.

Geddes MacGregor, Dictionary of Religion and Philosophy, New York: Paragon House, 1989

certainty : (m.) nicchaya; asandeha. (nt.) niyatatta.

A.P. Buddhadatta Mahathera, Concise Pali-English and English-Pali Dictionary [available as digital version from Metta Net, Sri Lanka]