A History of Indian Philosophy Volume 1

by Surendranath Dasgupta | 1922 | 212,082 words | ISBN-13: 9788120804081

This page describes the philosophy of inference (anumana): a concept having historical value dating from ancient India. This is the seventeenth part in the series called the “the nyaya-vaisheshika philosophy”, originally composed by Surendranath Dasgupta in the early 20th century.

Inference (anumāna) is the second means of proof (pramāṇa) and the most valuable contribution that Nyāya has made has been on this subject. It consists in making an assertion about a thing on the strength of the mark or liṅga which is associated with it, as when finding smoke rising from a hill we remember that since smoke cannot be without fire, there must also be fire in yonder hill. In an example like this smoke is technically called liṅga, or hetu. That about which the assertion has been made (the hill in this example) is called pakṣa, and the term “fire” is called sādhya. To make a correct inference it is necessary that the hetu or liṅga must be present in the pakṣa, and in all other known objects similar to the pakṣa in having the sādhya in it (sapakṣa-sattā), i.e., which are known to possess the sādhya (possessing fire in the present example). The liṅga must not be present in any such object as does not possess the sādhya (vipakṣa-vyāvṛtti absent from vipakṣa or that which does not possess the sādhya). The inferred assertion should not be such that it is invalidated by direct perception (pratyakṣa) or the testimony of the śāstra (abādhita-viṣayatva).

The liṅga should not be such that by it an inference in the opposite way could also be possible (asat-pratipakṣa). The violation of any one of these conditions would spoil the certitude of the hetu as determining the inference, and thus would only make the hetu fallacious, or what is technically called hetvābhāsa or seeming hetu by which no correct inference could be made. Thus the inference that sound is eternal because it is visible is fallacious, for visibility is a quality which sound (here the pakṣa) does not possess[1]. This hetvābhāsa is technically called asiddha-hetu. Again, hetvābhāsa of the second type, technically called virnddha-hetu , may be exemplified in the case that sound is eternal, since it is created; the hetu “being created” is present in the opposite of sādhya (vipakṣa), namely non-eternality, for we know that non-eternality is a quality which belongs to all created things.

A fallacy of the third type, technically called anaikāntika-hetu , is found in the case that sound is eternal, since it is an object of knowledge. Now “being an object of knowledge” (prameyatva) is here the hetu, but it is present in things eternal (i.e. things possessing sādhya), as well as in things that are not eternal (i.e. which do not possess the sādhya), and therefore the concomitance of the hetu with the sādhya is not absolute (anaikāutika). A fallacy of the fourth type, technically called kālātyayāpadiṣṭa, may be found in the example—fire is not hot, since it is created like a jug, etc. Here pratyakṣa shows that fire is hot, and hence the hetu is fallacious. The fifth fallacy, called prakaraiiasama , is to be found in cases where opposite hetus are available at the same time for opposite conclusions, e.g. sound like a jug is non-eternal, since no eternal qualities are found in it, and sound like ākāśa is eternal, since no non-eternal qualities are found in it.

The Buddhists held in answer to the objections raised against inference by the Cārvākas, that inferential arguments are valid, because they are arguments on the principle of the uniformity of nature in two relations, viz. tādātmya (essential identity) and tadutpatti (succession in a relation of cause and effect). Tādātmya is a relation of genus and species and not of causation ; thus we know that all pines are trees, and infer that this is a tree since it is a pine; tree and pine are related to each other as genus and species, and the co-inherence of the generic qualities of a tree with the specific characters of a pine tree may be viewed as a relation of essential identity (tādātmya). The relation of tadutpatti is that of uniformity of succession of cause and effect, e.g. of smoke to fire.

Nyāya holds that inference is made because of the invariable association (niyama) of the liṅga or hetu (the concomitance of which with the sādhya has been safeguarded by the five conditions noted above) with the sādhya, and not because of such specific relations as tādātmya or tadutpatti. If it is held that the inference that it is a tree because it is a pine is due to the essential identity of tree and pine, then the opposite argument that it is a pine because it is a tree ought to be valid as well; for if it were a case of identity it ought to be the same both ways. If in answer to this it is said that the characteristics of a pine are associated with those of a tree and not those of a tree with those of a pine, then certainly the argument is not due to essential identity, but to the invariable association of the liṅga (mark) with the liṅgin (the possessor of liṅga), otherwise called niyama.

The argument from tadutpatti (association as cause and effect) is also really due to invariable association, for it explains the case of the inference of the type of cause and effect as well as of other types of inference, where the association as cause and effect is not available (e.g. from sunset the rise of stars is inferred). Thus it is that the invariable concomitance of the liṅga with the liṅgin, as safeguarded by the conditions noted above, is what leads us to make a valid inference[2].

We perceived in many cases that a liṅga (e.g. smoke) was associated with a liṅgin (fire), and had thence formed the notion that wherever theie was smoke there was fire. Now when we perceived that there was smoke in yonder hill, we remembered the concomitance (vyāpti) of smoke and fire which we had observed before, and then since there was smoke in the hill, which was known to us to be inseparably connected with fire, we concluded that there was fire in the hill. The discovery of the liṅga (smoke) in the hill as associated with the memory of its concomitance with fire (tṛtīya-liṅga-parāmarśa) is thus the cause (anumitikaraṇa or anumāna) of the inference (anumiti). The concomitance of smoke with fire is technically called vyāpti. When this refers to the concomitance of cases containing smoke with those having fire, it is called bahirvyāpti ; and when it refers to the conviction of the concomitance of smoke with fire, without any relation to the circumstances under which the concomitance was observed, it is called antarvyāpti. The Buddhists since they did not admit the notions of generality, etc. preferred antarvyāpti view of concomitance to bahirvyāpti as a means of inference[3].

Now the question arises that since the validity of an inference will depend mainly on the validity of the concomitance of sign (hetu) with the signate (sādhya), how are we to assure ourselves in each case that the process of ascertaining the concomitance (vyāp-tigraha) had been correct, and the observation of concomitance had been valid. The Mīmāṃsā school held, as we shall see in the next chapter, that if we had no knowledge of any such case in which there was smoke but no fire, and if in all the cases I knew I had perceived that wherever there was smoke there was fire, I could enunciate the concomitance of smoke with fire But Nyāya holds that it is not enough that in all cases where there is smoke there should be fire, but it is necessary that in all those cases where there is no fire there should not be any smoke, i.e. not only every case of the existence of smoke should be a case of the existence of fire, but every case of absence of fire should be a case of absence of smoke.

The former is technically called anvayavyāpti and the latter vyatirekavyāpti. But even this is not enough. Thus there may have been an ass sitting, in a hundred cases where I had seen smoke, and there might have been a hundred cases where there was neither ass nor smoke, but it cannot be asserted from it that there is any relation of concomitance, or of cause and effect between the ass and the smoke. It may be that one might never have observed smoke without an antecedent ass, or an ass without the smoke following it, but even that is not enough. If it were such that we had so experienced in a very large number of cases that the introduction of the ass produced the smoke, and that even when all the antecedents remained the same, the disappearance of the ass was immediately followed by the disappearance of smoke (yasmin sati bhavanam yato vinā na bhavanam iti bhūyodarśanaṃ, Nyāyamañjarī, p. 122), then only could we say that there was any relation of concomitance (vyāpti) between the ass and the smoke[4].

But of course it might be that what we concluded to be the hetu by the above observations of anvaya-vyatireka might not be a real hetu, and there might be some other condition (upādhi) associated with the hetu which was the real hetu. Thus we know that fire in green wood (ārdrendhana) produced smoke, but one might doubt that it was not the fire in the green wood that produced smoke, but there was some hidden demon who did it. But there would be no end of such doubts, and if we indulged in them, all our work endeavour and practical activities would have to be dispensed with (vyāghāta). Thus such doubts as lead us to the suspension of all work should not disturb or unsettle the notion of vyāpti or concomitance at which we had arrived by careful observation and consideration[5].

The Buddhists and the naiyāyikas generally agreed as to the method of forming the notion of concomitance or vyāpti (vyāptigraha), but the former tried to assert that the validity of such a concomitance always depended on a relation of cause and effect or of identity of essence, whereas Nyāya held that neither the relations of cause and effect, nor that of essential identity of genus and species, exhausted the field of inference, and there was quite a number of other types of inference which could not be brought under either of them (e.g. the rise of the moon and the tide of the ocean). A natural fixed order that certain things happening other things would happen could certainly exist, even without the supposition of an identity of essence.

But sometimes it happens that different kinds of causes often have the same kind of effect, and in such cases it is difficult to infer the particular cause from the effect. Nyāya holds however that though different causes are often found to produce the same effect, yet there must be some difference between one effect and another. If each effect is taken by itself with its other attendant circumstances and peculiarities, it will be found that it may then be possible to distinguish it from similar other effects.

Thus a flood in the street may be due either to a heavy downpour of rain immediately before, or to the rise in the water of the river close by, but if observed carefully the flooding of the street due to rain will be found to have such special traits that it could be distinguished from a similar flooding due to the rise of water in the river. Thus from the flooding of the street of a special type, as demonstrated by its other attendant circumstances, the special manner in which the water flows by small rivulets or in sheets, will enable us to infer that the flood was due to rains and not to the rise of water in the river. Thus we see that Nyāya relied on empirical induction based on uniform and uninterrupted agreement in nature, whereas the Buddhists assumed a priori principles of causality or identity of essence.

It may not be out of place here to mention that in later Nyāya works great emphasis is laid on the necessity of getting ourselves assured that there was no such upādhi (condition) associated with the hetu on account of which the concomitance happened, but that the hetu was unconditionally associated with the sādhya 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 (upādhi) 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 vyāpti, 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 (bhñyodarścina).

Praśastapāda 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 (liṅga) 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 Nyāya qualifications of pakṣasattva, sapakṣasattva and vipakṣāsattva of a valid reason (hetu). Praśastapāda further quotes a verse to say that this is the same as what Kāśyapa (believed to be the family name of Kaṇāda) said.

Kaṇāda 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). VVe can infer by a reason because it is duly associated (prasiddhipūr-vakatva) with the object of inference. What this association was according to Kaṇāda 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 pakṣāsattva and sapakṣāsattva, for not only the present pakṣa (the ass) had no horns, but no horses had any horns, and the second is a case of vipakṣasattva, for those which are not cows (e.g. buffaloes) have also horns. Thus, it seems that when Praśastapāda says that he is giving us the view of Kaṇāda he is faithful to it. Praśastapāda 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 Kaṇāda’s enumeration of types of inference such as “a cause is inferred from its effect, or an effect from the cause,” etc., Praśastapāda 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, dṛṣṭa (from the experienced characteristics of one member of a class to another member of the same class), and sāmānyato dṛṣṭa.

Dṛṣṭa (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 (sāsnā), 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 sāmānyato dṛṣṭa. 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 (svani-ścitārtha) 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 parārthānumāna.

We know that the distinction of svārthānumāna (inference for oneself) and parārthānumāna (inference for others) was made by the Jains and Buddhists. Praśastapāda 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 parārthānumāna. But this need not be considered as an entirely new innovation of Praśastapāda, for in IX. 2, Kaṇāda himself definitely alludes to this distinction (asyedam kāryyakāra-nasambandhaścāvayavādbhavati). The five premisses which are called in Nyāya pratijñā, hetu dṛṣṭānta, upanaya, and nigamana are called in Vaiśeṣika pratijñā, apadeśa, nidarśana , anusandhāna , and pratyāmnāya. Kaṇāda however does not mention the name of any of these premisses excepting the second “apadeśa.” Pratijñā is of course the same as we have in Nyāya, and the term nidarśana is very similar to Nyāya dṛṣṭānta, but the last two are entirely different.

Nidarśana 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[6]).

He also points out cases of the fallacy of the example

(nidarśanābhāsa). Praśastapāda’s contribution thus seems to consist of the enumeration of the five premisses and the fallacy of the nidarśana, 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 Vaiśeṣika work which is now lost to us. It however definitely indicates that the study of the problem of inference was being pursued in Vaiśeṣika circles independently of Nyāya. There is no reason however to suppose that Praśastapāda borrowed anything from Diṅnāga as Professor Stcherbatsky or Keith supposes, for, as I have shown above, most of Praśastapāda’s apparent innovations are all definitely alluded to by Kaṇāda himself, and Professor Keith has not discussed this alternative. On the question of the fallacies of nidarśana, unless it is definitely proved that Diṅnāga preceded Praśastapāda, there is no reason whatever to suppose that the latter borrowed it from the former[7].

The nature and ascertainment of concomitance is the most important part of inference. Vātsyāyana says that an inference can be made by the sight of the liṅga (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 liiiga-parāmarśa , 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 (smṛtyanugrhīto liṅgaparāmarśo). But he is silent with regard to the nature of concomitance. Udyotakara s criticisms of Diṅnāga as shown by Vācaspati have no reference to this point.

The doctrine of tādātmya and tadutpatti was therefore in all probability a new contribution to Buddhist logic by Dharmakīrtti. Dharmakīrtti’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[8]. Vācaspati 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 (tādātmya 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 Vācaspati’s answer is that if even after observing a large number of cases and careful search such conditions (upādhi) 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 Pañcakāraṇī 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[9].

In early Nyāya books three kinds of inference are described, namely pūrvavat, śeṣavat, and sāmānyato-dṛṣṭa. Pūrvavat is the inference of effects from causes, e.g. that of impending rain from heavy dark clouds; śeṣavat is the inference of causes from effects, e.g. that of rain from the rise of water in the river; sāmānyato-dṛṣṭa 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. Nyāyamañjarī mentions another form of anumāna, namely pariśeṣamāna (reductio ad absurdum), which consists in asserting anything (e.g. consciousness) of any other thing (e.g. ātman), 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 (sādhya) by virtue of the unconditional and invariable concomitance of the hetu, called the vyāpti-niyama. In the new school of Nyāya (Navya-Nyāya) a formal distinction of three kinds of inference occupies an important place, namely anvayavyatireki, kevalānvayi, and kevalavyatireki. Anvayavyatireki is that inference where the vyāpti 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 (svārthānumāna) or for the sake of convincing others (parārthānumāna). In the latter case, when it was necessary that an inference should be put explicitly in an unambiguous manner, five propositions (avayavas) were regarded as necessary, namely pratijña (e.g. the hill is fiery), hetu (since it has smoke), udā-haraṇa (where there is smoke there is fire, as in the kitchen), upanaya (this hill has smoke), nigamana (therefore it has got fire). Kevalānvayi is that type of inference, the vyāpti 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 (idaṃ, vācyam prameyatvāt).”

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 (vācyatva); the vyāpti here has therefore to be based necessarily on cases of agreement—wherever there is prameyatva or an object of knowledge, there is vācyatva 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.

Footnotes and references:


It should be borne in mind that Nyāya did not believe in the doctrine of the eternality of sound, which the Mīmāmsā did. Eternality of sound meant with Mīmāmsā the theory that sounds existed as eternal indestructible entities, and they were only manifested in our ears under certain conditions, e.g. the stroke of a drum or a particular kind of movement of the vocal muscles.


See Nyāyamañjarī on anumāna.


See Antarvyāptisamarthcina , by Ratnākaraśānti in the Six Buddhist Nyāya Tracts, Bibliotheca īndica, 1910.


See Tātparyaṭīkā on anumāna and vyāptigraha.


Tātparyaṭīkā on vyāptigraha, and Tattvacintāmaṇi of Gaṅgeśa on vyāptigraha.


Dr Vidyābhūsana says that

“An example before the time of Dignāga 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). Asaṅga made the example more serviceable to reasoning, but Dignāga 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 Vatsyāyana had an imperfect example as “like a kitchen” (śabdaḥ utpattidharmakatvādanityaḥ sthālyādivat , I. i. 36), but Praśastapāda has it in the proper form. Whether Praśastapāda borrowed it from Diñnāga or Diñnāga from Praśastapāda cannot be easily settled.


Praśastapāda’s bhāṣya with Nyāyakandalī, pp. 200-255.


Kāryyakāraṇabhāvādvā svabhāvādva niyūmakñt avinābhāvaniyamo’ darśanānna na darśanāt.

     Tātparyaṭīkā , p. 105.


Vātsyāyana’s bhāsya, Udyotakara’s Vārttika and Tātparyyatīkā , I. i. 5.

Like what you read? Consider supporting this website: