The correct or the valid knowledge in Indian thought is called prama which stands for awareness of a thing as it really is and that which is free from misapprehension . The Indian thought is therefore concerned with what generates correct knowledge as also with what generates incorrect knowledge. The incorrect or invalid knowledge is called aprama or bhrama.
The sources of correct knowledge are known as pramana . It is a method , a device to verify the truth of a piece of knowledge that is acquired. It is largely a method of deduction but at times has room for intuition. Each school of thought adopted its method of cognition, pramana. The differences among the schools were more in their emphasis and on their perception of truth ratherthan in the methods they employed. For instance , Samkhya defined truth as the mode of agreeing entirely with the object .The Nyaya school thought that truth must be effective and should lead us to the desired object. Utility , according to them , was the criterion of truth. Vedanta , on the other hand , defined truth as that which was free from contradictions.
Valid knowledge , in general , emphasizes objectivity. Consistency in time and space is a necessary feature of Valid knowledge. What contributes to such knowledge is pramana . The purpose of pramana is to define its object clearly , specifically and to illuminate the object. It does not however generate a new fact but it brings forth experiencing a fact as it actually is. The pramanas , however , have their own limited fields of operation ; their validity is restricted to what they can possibly reveal. That perhaps explains the multiplicity of methods employed to verify ones experiences.
Charvakas accepted only one source of valid knowledge , viz. sense perception or direct observation (pratyaksha). Charvakas were strictly empirical and dismissed subjective experiences beyond sensations as being irrelevant. The Vaisheshikas considered deductive analysis or reasoning ( anumana , inference) as an additional method. They explained the nature and characteristics of the physical world by employing the first method pratyaksha but introduced the element of soul by inference. The Buddhists too relied heavily on inference . The Samkhya thinkers said that in addition to sense-perception and inference , the verbal testimony Sabda (which included scriptural testimony) could also be a means of valid knowledge . The Samkhya being essentially atheistic confined Sabda to mean unerring authority (aapta –vacana) in matters pertaining to daily life.
The Nyaya school was essentially logistic in its orientation. It tried to examine the sources and contents of valid knowledge. It built a logical link between the subject , the knower(pramata) ; the means or method of obtaining knowledge (pramana) ; and the object , the knowable (prameya) . In addition , it put forth analogy (Upama) as the fourth method . Analogy , it said , comprehensively included in itself the other three methods. Analogy was , however , not an altogether new method . The Samkhya classified analogy under verbal testimony which in turn was included under inference. Nyaya however assigned an independent status to the method of analogy.( For more on Nyaya please see Nyaya a scheme of logic )
The Mimamsa school added two more methods Viz. presumption (arthapatti) and non-apprehension (abhava). Presumption , the Mimamsakas said , comes in handy when direct-sense perception, inference, verbal testimony or comparison do not directly help . The other line abhava or non-apprehension is a method to ascertain the non-existence of a thing. It too was treated as an independent and a positive process of knowing a thing.
Vedanta accepted all the six methods as means’s for acquiring valid knowledge.
It does not mean that one school or the other employed a particular method to the exclusion of all the other methods . Each of the methods had its own sphere of functioning; each supplemented the other ; and together contributed to the empirical knowledge of an object. Very often , a school of thought employed all the methods but laid emphasis on a particular method depending on the orientation of that school. For instance , the first four schools (Charvaka, Nyaya, Vaisheshika and Samkhya) relied heavily on argumentation and were therefore described as “ reason-dominant (yukthi-pradhana) “.
Of the six methods, the ones that were directly employed were the sense-perception (observation) , inference (deductive reasoning) and scriptural authority ; while presumption and non-apprehension were clubbed under inference. And here again, inference by definition was guided by sense-perception. Thus , observation and scriptural authority stood out as the only two independent methods.
It was however around Sabda the scriptural authority that differences sprang up among the various schools .Mimamsakas put undue stress on scriptural authority , by which they meant the authority of the Vedas which they declared were eternal and therefore infallible. They subordinated every other method of cognition to authority of the Vedas ( particularly to the authority of the Brahmana portions) . Samkhya and Nyaya schools , in contrast , refused to accept the Vedas as the sole source of scriptural authority . They said the words of any trustworthy person (aptha) could be considered a source of valid knowledge and the Vedas could be one such. The Vaisheshika and the Nyaya school to a certain extent , refused to accept the divine origin of the Vedas but admitted the Vedas as one among the valid scriptural authority. The Buddhists went a step further; they rejected the divine origin of the Vedas and refused to accept the Vedas as a source of valid knowledge.
The Vedanta took a rather an intermediate position. It accepted the authority of the Vedas but tilted towards its informative passages viz. the Upanishads , almost to the exclusion of its ritualistic portions. Further , it said , sense -perception acts as a guide for the world while scriptures help to appreciate the significance of the reality . Vedanta therefore recommended a combination of scriptures (sruthi) and reason (yukthi or tarka). The debate on the undisputed authority of the Vedas and its authorship was , in a way , sidetracked.
The genius of Sri Sankara was that he rose above the apparent contradictions and charted a new path of reason and intuition.
He did not regard the scriptures either as eternal or immutable. He accepted the scriptures but conceded it a limited authority . “ In inquiries concerning religious conduct it may be that the scripture is the sole authority . But it cannot be so in our investigation into reality . Here , scriptures as well as other sources of knowledge such as phenomenal experience become valid , according to necessity. For , after all , the purpose of such investigation is to end in transcendental experience and to inform us about reality” (VSB 1,1 ,2) .
He said when the meaning of the scripture was not clear or when there were apparent contradictions , one must rely on reason . He also cautioned that reason can often be barren (sushka tarka) when it was devoid of intuition . He spoke of the value of reason blessed by intuition that becomes a part of ones experience.
According to Sri Sankara , no method is valid if it is contradicted by other methods. Each method is valid inasmuch as it makes known what is not made known by other methods. For instance , Intuition becomes suspect when it is contradicted by reason ; similarly reason is futile if not supported by intuition. The two have to compliment each other. He declared, “Intuition is not opposed to intellect. Reality is experience. Realizing the Supreme Being is within ones experience”.
Sri Sankara placed personal experience , common as well as extraordinary , above all the other methods of cognition . He gave credence to an individual’s subjective experience. He said that if the scriptures say things that contradict our perceptional experience , then they loose their credibility. “ Even a hundred scriptural passages will not become authoritative when they , for instance , announce that fire is cool or dark”(VSB 43,14).
Among the misconceptions that have grown around Sri Sankara, the persistent and the most erroneous one is that he regarded world as an illusion. It is a gross misrepresentation of Sri Sankara . He accepted the phenomenal reality of the world. He gave credence to an individual’s subjective experience in the world. He said that individual’s experience cannot be disputed, because the experience he went through was real to him; though that might not be real from the absolute point of view .Sri Sankara drew a distinction between the absolute view (para_marthika )and the relative view(vyavaharika) of things.
Sri Sankara explained that vyavaharika (relative) and para_marthika (absolute) are both real. However, that relative reality is “limited” in the sense it is biologically or mechanically determined and is subject to contradictions. The absolute on the other hand is beyond contradictions. By “absence of contradiction “ (badha-rahithyam), he did not refer merely to the earlier knowledge being contradicted by later knowledge, but also to the experiences at one plane of reality being contradicted by those at the other plane. Sri Sankara was careful to point out that the two dimensions – Vyavaharika and Paramarthika– are two levels of experiential variations. That does not mean they are two orders of reality. They are only two perspectives. Whatever that is there is there ; and That (tat) is REAL and is not affected by our views one way or the other.
Sri Sankara said the methods of cognition such as sense-perception and inference are dependent on sense organs , which in turn function within the ambit of body-consciousness. The Self cannot be regarded as a subject (knower , employing a method) and unless there be a subject it is meaningless to speak of a method. Therefore all methods , including scriptures , have only phenomenal relevance.
Thus , in a very real sense , all the methods of cognition are relevant only in the phenomenal, vyavaharika (relative) context of the world that we live in . All those methods cease to be authentic beyond the relative existence.
Reality is experience (anubhava). Realizing the Supreme Being is within ones experience.