Chapter 3.2 - Classifications of Inference (Anumana)

Naiyayikas classify Anumana (inference) into three different ways depending on the nature, psychology and nature of indication. According to the nature of the vyapti or the universal relation between the middle and major terms of inference, it has been divided into: a prior (purvavat) a posterior (sheshavat) and commonly seen (samanyatodrsta)^[1]

Vatsyayana gives two types of interpretations to purvavat. It is an inference in which the effect is inferred from the cause. The inference of rain seeing a cloud is the example given. Another example is that type of inference in which out of two things one that is not perceived is inferred from the perceived one on the basis of a former experience. The inference of the unseen fire from the perceived smoke on the basis of the previous experience inferred from their co-existence. According to Jayanta, purvavat is the universal concomitance between the reason and the consequence which is responsible for the establishment of one by the other.

Sheshavat as its name indicates is the inference of the unperceived cause from the perceived effect. The middle term is related as an effect to the major term and is therefore, consequent to it. For instance, the inference of rain from the ascent of water in the river not seen before.

Samanyatodrista refers to the inference based on merely experience. Seeing the sun in the East in the morning, in the middle in the afternoon and in the west at evening twilight, the movement is inferred.

Psychologically, it has been classified into (i) svartha (one’s own inferential knowledge) and parartha (inferential knowledge for another).^[2] When the goal of inference is to gain knowledge of an unknown object then it is called svartha. In this kind of inference, one attempts to arrive at a conclusion by himself by relating it to the major and minor premises. Hence svartha is for oneself. If the motive is for demonstrating the truth of the conclusion to others it is called as Pararthanumana. Here conclusion is arrived at through justification of the middle term that leads to it. A man having inferred the existence of fire in a hill lays it down as a thesis and proves it as a conclusion following from the major and minor premises and their combination into a third premise, it is pararthanumana.

The latter has a five membered syllogism viz., pratijna, hetu, udaharana, upanaya and nigamana.

1. Pratijna (preposition) — the hill is fiery
2. Hetu (reason) — because it is smoky
3. Udaharana (example) — wherever smoke exists, fire also exists as in kitchen.
4. Upanaya (subsumptive correlative) — there is smoke on the hill.
5. Nigamana (conclusion) — Hence, the hill is fiery

The third classification mostly recommended by the Neo-logicians divides Anumana into kevalanvayi, kevala-vyatireki and anvaya vyatireki.^[3] It depends on the nature of the indications by which the knowledge of vyapti or the universal proposition involved in inference is obtained.

If the middle term is positively related to the major term it is referred as Kevalanvayi (purely positive reason). The term agrees only in presence, there being no negative instance of their agreement in absence. For instance, all knowable objects are nameable. The pot is a knowable object; therefore the pot is nameable.

If the middle term is the differentium of the minor term and is always negatively related to the major term, then it is Kevalavyatireki (purely negative reason).^[4]

Anvayavyatireki inference is when the middle term is both positively and negatively related to the major term.^[5] Vyapti between the middle and major is in respect of both presence and absence. There is double agreement between the terms-they agree in presence in the positive instances and they also agree in absence in the negative instances. For e.g.,

1. All things which have smoke have fire;
2. The hill has smoke;
3. The hill has fire; and no-non fiery things have smoke;
4. This hill is not non-fiery.
5. That is this hill has fire.

Syllogism as typical form of inferential reasoning is accepted by all systems of Indian philosophy. A few of the old Naiyayikas speaks of ten members of syllogism viz.

1. Jijnasa — on the desire to know the truth.
2. Samsaya — or doubt about real nature of a thing.
3. Shakyaprapti — or the capacity of the pramanas to lead to true knowledge.
4. Prayojana — or the purpose of making an inference
5. Samshaya vyudasa — or the removal of all doubts the truth of an inference.
6. Pratijna — as the first proposition
7. Hetu — or the reason
8. Udaharana — or the example
9. Upanaya — or the application of the example and
10. Nigamana — or final conclusion.^[6]

Criticizing the ten member syllogism Vatsyayana disagree with the first five and state them as irrelevant. The remaining five members of the syllogism are explained by the Naiyayikas as follows.

Pratijna (proposition):

Pratijna or proposition the first of the five members of syllogism is a statement of one’s position and includes assertion that can be affirmative or negative of certain unknown quality on character based on some experience. It includes a subject and a predicate and it states the subject of the inference and what is connected to it. E.g., the hill is fiery or sound is not eternal.

Hetu (reason):

Hetu or the reason, the second member of the syllogism is considered as the middle premise or middle proposition of the syllogism. It includes statement of the mark or the sign (linga) present in the subject or the minor term. It affirms that the latter possesses a certain property predicted by it. Accordingly, the middle term by which the paksha or the minor term is related or not to the sadhya or the major term will be known. In the proposition, the hill is fiery;the hetu or middle proposition will be because of smoke.

Udaharana (example):

Udaharana or example is the third member of syllogism. It correlates to knowing the universal relation between the major and middle terms to some similar instance. The hetu or the middle term proves the presence or absence of the major in the minor only as it is connected with the minor on the one hand, and universally related to the major on the other. Therefore universal relation between the major and middle terms must be to understand it as an essential member of the syllogism.

Upanaya (application):

Upanaya or application, the fourth member of syllogism comprises application of the universal proposition with its udaharana to the subject or the minor term of the Anumana. It should be understood that while udaharana shows the universal relation or absence between the major and middle terms, upanaya indicates the presence or the absence of the middle and the minor term. Hence, upanaya may be referred to as the minor premise of the syllogism and may be a universal affirmative or negative proposition.

Nigamana (final conclusion):

The last in the five member syllogism is Nigamana or final conclusion. It is arrived at through the preceding four steps. Through these steps they merge to a point at which what is depicted by the first proposition comes to true. The inference follows the steps. It consists of the re-statement of the pratijna or the first proposition that is proved by the major and minor premises. E.g., therefore the hill is fiery.

The logical terms included in the process of the syllogism, as for Naiyayikas are;

• S is P The hill is fiery
• S is M Due to smokiness
• M is P Smoke is fiery. Whichever is smoky is fiery
• S is M So the hill (has smoke pervaded by fire)
• S is P Therefore it is such.
• S is P Therefore the hill is fiery.^[7]

Footnotes and references:

[1]:

Nyayasutram (Nyayasutra), 1.1.5

[2]:

Tarkabhasha (Tarkabhasha), p.9

[3]:

S.C. Chatterjee, Nyaya theory of Knowledge, Bharatiya Kala Prakashan: Delhi, p.268.

[4]:

Tarkabhasha p.10

[5]:

Ya Tattva Cintamani (Tattva-Cintamani), Ch.II

[6]:

-Nyayabindu, 1.1. 32.

[7]:

S.C. Chatterjee, Nyaya theory of Knowledge, Bharatiya Kala Prakashan, New Delhi, p. 277.