OF the six systems of thought which arose in this period, the Nyaya and the Vaisesika systems represent the analytic type of philosophy. The history of the Nyaya literature extends over twenty centuries and the long history of the thought and the vast amount of significant literature in this one system is typical of all the systems. The distinctive character of the Nyaya philosophy is its critical examination of the objects of knowledge by means of the canons of logical proof. Systems of Hindu thought generally accept the fundamental principles of the Nyaya logic. The physical and metaphysical views of the Nyaya atomistic realism are essentially the same as those of the Vaisesika.

“Nyaya” literally means that by which the mind is led to a conclusion. We are led to conclusions by arguments or reasoning. These arguments are either valid or invalid. ” Nyaya ” in popular usage means ” right ” or “just,” and so Nyaya becomes the science of right or just reasoning. It is, in a wider sense, the science of demonstration or correct knowledge (pramana sastra). In knowledge we can distinguish four factors: subject (pramat r), object (prameya), the resulting state of cognition (pramiti), and
the means of knowledge (pramana). The nature of knowledge as valid or invalid depends on the last, pramana. By means of the pramanas we are led to a right apprehension of objects and are enabled to test the validity of knowledge.

Intuition (pratyaksa) is the most important. Though it meant senseperception originally, it soon came to include all immediate apprehension, whether through the aid of the senses or not. Gautama’s definition of sense perception mentions the different factors involved, the senses (indriyas), their objects (arthas), the contact of the two (sannikarsa), and the cognition (jnana) produced by the contact. There are five sense organs~ eye, ear, nose, tongue, and skin, which are of the same nature as the five elements, light, ether, earth, water, and air, whose special qualities of color, sound, smell, taste, and tangibility are manifested by them. Mind (manas) is a prerequisite of perception. It mediates between the self and the senses.

There are two kinds of perception, determinate and indeterminate. In the former we acquire knowledge of the genus to which the perceived object belongs, the specific qualities which distinguish it from other members of the class, and the union between the two. These specific elements are absent in indeterminate perception, which is of the type of simple apprehension. The latter is the starting point of all knowledge, though it is not itself knowledge. There are several views of this distinction between determinate and indeterminate perception. Later logicians, e.g., Dharmakirti, distinguished four kinds of perception: sense perception, mental perception, self consciousness, and Yogic intuition.

Inference (anumana) means, literally, knowledge which follows other knowledge. It is also defined as knowledge which is preceded by perception. It includes both deductive and inductive inference. There can be no inference without a universal connection (vyapti). We infer that the mountain is on fire from the fact that there is smoke on the mountain, because smoke is universally connected with fire. The Nyaya syllogism has five elements: (1) the proposition to be established (the hill is on fire); (2) the reason (because it smokes); (3) the example (whatever has smoke has fire, for example, a kitchen); (4) the application (so does this hill); and (5) the statement of the conclusion (the hill is on fire). There are requirements to which each of these five members of an argument must conform. For example in an interesting contrast to Western traditional formal logic the third member, the example, indicates that the universal proposition which is the logical ground of the inference is based on particular and factual instances. Attempts have been made to reduce the number of members of the syllogism to three. All are agreed that the essentials of the inference are the universal relation and the reason (the minor premise). General propositions are traced to an enumeration of instances, positive and negative, intuition of the universal, and indirect proof by which it is shown that no other hypothesis can account for the facts.

Upamana is comparison or analogy by which we gain knowledge of a thing from its similarity to another. The similarity should be essential, not superficial.

Sabda, verbal knowledge or testimony, refers to authority. Under this, Naiyayikas discuss words, their meanings, and whether they refer to individual, or form, or genus.

The Nyaya thinkers believe that non existence (abhava) can be inferred, and so it need not be given an independent place along with the other forms of knowledge.

We find in the Nyaya discussions of memory, doubt, fallacies of reasoning, etc. The test of truth is successful action.

The main selections from the Nyaya system and from all six systems which follow consist of sutras, short aphoristic statements, and explanatory commentaries on these satras. In general, the sutras are taken from The Nyaya Sutras of Gotama (3rd century B.C.), translated by S. C. Vidyabhusana, tr., Sacred Books of the Hindus, viii (Allahabad: The Panini Office, 1930), and the commentaries the portion in smaller type are from Gautama’s Nyayasutras with Vatsyayana’s Bhasya, translated by Ganganatha jha (Poona: Oriental Book Agency, 1939). jha’s translation of the sutras is used occasionally and is so noted. Sometimes a new, alternate translation is suggested.

In the case of a few difficult passages, the commentary is taken from the volume of the Sacred Book of the Hindus in which case it is noted thus: [S.B.H.] – aithough these commentaries are not literal translations of the original bhasya (commentary).

While the Nyaya is a comprehensive system and includes extensive exposition of metaphysical and psychological principles, the system, as noted above, is especially important for its logical doctrines, and so these are included at length in the selections, while Books III and IV are omitted entirely. The substance of the material of these two books will be included in the sister system, Vaisesika, in the next chapter.

A short selection is added from Udayana Acarya’s (10th century A.D.) Kusumanjalii: The Kusumanjali or Hindu Proof of the Existence of a Supreme Being, with the commentary of Hari Dasa Bhattacarya, translated by E. B. Cowell (Calcutta: Baptist Mission Press, 1864).