It may not be out of place here to mention that in later Nyaya works great emphasis is laid on the necessity of getting ourselves assured that there was no such upadhi (condition) associated with the hetu on account of which the concomitance happened, but that the hetu was unconditionally associated with the sadhya in a relation of inseparable concomitance. Thus all fire does not produce smoke; fire must be associated with green wood in order to produce smoke. Green wood is thus the necessary condition (upadhi) without which, no smoke could be produced. It is on account of this condition that fire is associated with smoke; and so we cannot say that there is smoke because there is fire. But in the concomitance of smoke with fire there is no condition, and so in every case of smoke there is fire. In order to be assured of the validity of vyapti, it is necessary that we must be assured that there should be nothing associated with the hetu which conditioned the concomitance, and this must be settled by wide experience (bhuyodarshana).

Prashastapada in defining inference as the “knowledge of that (e.g. fire) associated with the reason (e.g. smoke) by the sight of the reason” described a valid reason (linga) as that which is connected with the object of inference (anumeya) and which exists wherever the object of inference exists and is absent in all cases where it does not exist. This is indeed the same as the Nyaya qualifications of pakshasattva, sapakshasattva and vipakshasattva of a valid reason (hetu). Prashastapada further quotes a verse to say that this is the same as what Kashyapa (believed to be the family name of Kanada) said. Kanada says that we can infer a cause from the effect, the effect from the cause, or we can infer one thing by another when they are mutually connected, or in opposition or in a relation of inherence (IX. ii. 1 and III. i. 9). We can infer by a reason because it is duly associated (prasiddhipurvakatva) with the object of inference. What this association was according to Kanada can also be understood for he tells us (III. i. 15) that where there is no proper association, the reason (hetu) is either non-existent in the object to be inferred or it has no concomitance with it (aprasiddha) or it has a doubtful existence sandigdha).

Thus if I say this ass is a horse because it has horns it is fallacious, for neither the horse nor the ass has horns. Again if I say it is a cow because it has horns, it is fallacious, for there is no concomitance between horns and a cow, and though a cow may have a horn, all that have horns are not cows. The first fallacy is a combination of pakshasattva and sapakshasattva, for not only the present paksha (the ass) had no horns, but no horses had any horns, and the second is a case of vipakshasattva, for those which are not cows (e.g. buffaloes) have also horns. Thus, it seems that when Prashastapada says that he is giving us the view of Kanada he is faithful to it. Prashastapada says that wherever there is smoke there is fire, if there is no fire there is no smoke. When one knows this concomitance and unerringly perceives the smoke, he remembers the concomitance and feels certain that there is fire. But with regard to Kanada’s enumeration of types of inference such as “a cause is inferred from its effect, or an effect from the cause,” etc., Prashastapada holds that these are not the only types of inference, but are only some examples for showing the general nature of inference. Inference merely shows a connection such that from this that can be inferred. He then divides inference into two classes, drishta (from the experienced characteristics of one member of a class to another member of the same class), and samanyato drishta.

Drishta (perceived resemblance) is that where the previously known case and the inferred case is exactly of the same class. Thus as an example of it we can point out that by perceiving that only a cow has a hanging mass of flesh on its neck (sasna), I can whenever I see the same hanging mass of flesh at the neck of an animal infer that it is a cow. But when on the strength of a common quality the inference is extended to a different class of objects, it is called samanyato drishta. Thus on perceiving that the work of the peasants is rewarded with a good harvest I may infer that the work of the priests, namely the performance of sacrifices, will also be rewarded with the objects for which they are performed (i.e. the attainment of heaven). When the conclusion, to which one has arrived (svanishcitartha) is expressed in five premisses for convincing others who are either in doubt, or in error or are simply ignorant, then the inference is called pararthanumana.

We know that the distinction of svarthanumana (inference for oneself) and pararthanumana (inference for others) was made by the Jains and Buddhists. Prashastapada does not make a sharp distinction of two classes of inference, but he seems to mean that what one infers, it can be conveyed to others by means of five premisses in which case it is called pararthanumana. But this need not be considered as an entirely new innovation of Prashastapada, for in IX. 2, Kanada himself definitely alludes to this distinction (asyedam karyyakaranasambandhashcavayavadbhavati). The five premisses which are called in Nyaya pratijna, hetu drishtanta, upanaya, and nigamana are called in Vaisheshika pratijna, apadesha, nidarshana, anusandhana, and pratyamnaya. Kanada however does not mention the name of any of these premisses excepting the second “apadesha.” Pratijna is of course the same as we have in Nyaya, and the term nidarshana is very similar to Nyaya drishtanta, but the last two are entirely different.

Nidarshana may be of two kinds,
(1) agreement in presence (e.g. that which has motion is a substance as is seen in the case of an arrow),
(2) agreement in absence (e.g. what is not a substance has no motion as is seen in the case of the universal being (l).

He also points out cases of the fallacy of the example (nidarshanabhasa). Prashastapada’s contribution thus seems to consist of the enumeration of the five premisses and the fallacy of the nidarshana, but the names of the last two premisses are so different from what are current in other systems that it is reasonable to suppose that he collected them from some other traditional Vaisheshika work which is now lost to us. It however definitely indicates that the study of the problem of inference was being pursued in Vaisheshika circles independently of Nyaya. There is no reason however to suppose that Prashastapada borrowed anything from Dinnaga as Professor Stcherbatsky or Keith supposes, for, as I have shown above, most of Prashastapada’s apparent innovations are all definitely alluded to by Kanada himself, and Professor Keith has not discussed this alternative. On the question of the fallacies of nidarshana, unless it is definitely proved that Dinnaga preceded Prashastapada, there is no reason whatever to suppose that the latter borrowed it from the former (2).

The nature and ascertainment of concomitance is the most important part of inference. Vatsyayana says that an inference can be made by the sight of the linga (reason or middle) through the memory of the connection between the middle and the major previously perceived. Udyotakara raises the question whether it is the present perception of the middle or the memory of the connection of the middle with the major that should be regarded as leading to inference. His answer is that both these lead to inference, but that which immediately leads to inference is lingaparamarsha, i.e. the present perception of the middle in the minor associated with the memory of its connection with the major, for inference does not immediately follow the memory of the connection, but the present perception of the middle associated with the memory of the connection (smrityanugrihito lingaparamarsho). But he is silent with regard to the nature of concomitance. Udyotakara’s criticisms of Dinnaga as shown by Vacaspati have no reference to this point The doctrine of tadatmya and tadutpatti was therefore in all probability a new contribution to Buddhist logic by Dharmakirtti. Dharmakirtti’s contention was that the root principle of the connection between the middle and the major was that the former was either identical in essence with the latter or its effect and that unless this was grasped a mere collection of positive or negative instances will not give us the desired connection (3).

Vacaspati in his refutation of this view says that the cause-effect relation cannot be determined as a separate relation. If causality means invariable immediate antecedence such that there being fire there is smoke and there being no fire there is no smoke, then it cannot be ascertained with perfect satisfaction, for there is no proof that in each case the smoke was caused by fire and not by an invisible demon. Unless it can be ascertained that there was no invisible element associated, it cannot be said that the smoke was immediately preceded by fire and fire alone. Again accepting for the sake of argument that causality can be determined, then also cause is known to precede the effect and therefore the perception of smoke can only lead us to infer the presence of fire at a preceding time and not contemporaneously with it. Moreover there are many cases where inference is possible, but there is no relation of cause and effect or of identity of essence (e.g. the sunrise of this morning by the sunrise of yesterday morning). In the case of identity of essence (tadatmya as in the case of the pine and the tree) also there cannot be any inference, for one thing has to be inferred by another, but if they are identical there cannot be any inference.

The nature of concomitance therefore cannot be described in either of these ways. Some things (e.g. smoke) are naturally connected with some other things (e.g. fire) and when such is the case, though we may not know any further about the nature of this connection, we may infer the latter from the former and not vice versa, for fire is connected with smoke only under certain conditions (e.g. green wood). It may be argued that there may always be certain unknown conditions which may vitiate the validity of inference. To this Vacaspati’s answer is that if even after observing a large number of cases and careful search such conditions (upadhi) cannot be discovered, we have to take it for granted that they do not exist and that there is a natural connection between the middle and the major. The later Buddhists introduced the method of Pancakarani in order to determine effectively the causal relation.

These five conditions determining the causal relation are

(1) neither the cause nor the effect is perceived,
(2) the cause is perceived,
(3) in immediate succession the effect is perceived,
(4) the cause disappears,
(5) in immediate succession the effect disappears.

But this method cannot guarantee the infallibility of the determination of cause and effect relation; and if by the assumption of a cause-effect relation no higher degree of certainty is available, it is better to accept a natural relation without limiting it to a cause-effect relation (4).

In early Nyaya books three kinds of inference are described, namely purvavat, sheshavat, and samanyato-drishta. Purvavat is the inference of effects from causes, e.g. that of impending rain from heavy dark clouds; sheshavat is the inference of causes from effects, e.g. that of rain from the rise of water in the river; samanyato-drishta refers to the inference in all cases other than those of cause and effect, e.g. the inference of the sour taste of the tamarind from its form and colour. Nyayamanjari mentions another form of anumana, namely parisheshamana (reductio ad absurdum), which consists in asserting anything (e.g. consciousness) of any other thing (e.g. atman), because it was already definitely found out that consciousness was not produced in any other part of man. Since consciousness could not belong to anything else, it must belong to soul of necessity. In spite of these variant forms they are all however of one kind, namely that of the inference of the probandum (sadhya) by virtue of the unconditional and invariable concomitance of the hetu, called the vyapti-niyama. In the new school of Nyaya (Navya-Nyaya) a formal distinction of three kinds of inference occupies an important place, namely anvayavyatireki, kevalanvayi, and kevalavyatireki. Anvayavyatireki is that inference where the vyapti has been observed by a combination of a large number of instances of agreement in presence and agreement in absence, as in the case of the concomitance of smoke and fire (wherever there is smoke there is fire (anvaya), and where there is no fire, there is no smoke (vyatireka)). An inference could be for one’s own self (svarthanumana) or for the sake of convincing others (pararthanumana). In the latter case, when it was necessary that an inference should be put explicitly in an unambiguous manner, live propositions (avayavas) were regarded as necessary, namely pratijna (e.g. the hill is fiery), hetu (since it has smoke), udaharana (where there is smoke there is fire, as in the kitchen), upanaya (this hill has smoke), nigamana (therefore it has got fire). Kevalanvayi is that type of inference, the vyapti of which could not be based on any negative instance, as in the case “this object has a name, since it is an object of knowledge (idam, vacyam prameyatvat).” Now no such case is known which is not an object of knowledge; we cannot therefore know of any case where there was no object of knowledge (prameyatva) and no name (vacyatva); the vyapti here has therefore to be based necessarily on cases of agreement–wherever there is prameyatva or an object of knowledge, there is vacyatva or name.

The third form of kevalavyatireki is that where positive instances in agreement cannot be found, such as in the case of the inference that earth differs from other elements in possessing the specific quality of smell, since all that does not differ from other elements is not earth, such as water; here it is evident that there cannot be any positive instance of agreement and the concomitance has to be taken from negative instances. There is only one instance, which is exactly the proposition of our inference - earth differs from other elements, since it has the special qualities of earth. This inference could be of use only in those cases where we had to infer anything by reason of such special traits of it as was possessed by it and it alone.

1. Dr Vidyabhushana says that “An example before the time of Dignaga served as a mere familiar case which was cited to help the understanding of the listener, e.g. The hill is fiery; because it has smoke; like a kitchen (example). Asanga made the example more serviceable to reasoning, but Dignaga converted it into a universal proposition, that is a proposition expressive of the universal or inseparable connection between the middle term and the major term, e.g. The hill is fiery; because it has smoke; all that has smoke is fiery as a kitchen” (Indian Logic, pp. 95, 96). It is of course true that Vatsyayana had an imperfect example as “like a kitchen” (shabdah utpatvidharmakatvadanuyah sthalyadivat, I.i. 36), but Prashastapada has it in the proper form. Whether Prashastapada borrowed it from Dignnaga or Dignnaga from Prashastapada cannot be easily settled.
2. Prashastapada’s bhashya with Nyayakandali, pp. 200-255.
3. Karyyakaranubhavadva svabhavadva niyamakat avinabhavaniyamo’ darshananna na darshanat. Tatparyatika, p. 105.
4. Vatsyayana’s bhasya, Udyotakara’s Varttika and Tatparyyatika, I.i. 5.

inference, kanada, linga, necessary condition, opposition, smoke fire, validity, valid reason