It is usual for logicians in India to hold that the only darsana that has to be consulted for a knowledge of logic (nyaya) is the darsana known by that name.  The purpose of that darsana is however different if we consider the topics chosen by it; there is firstly the consideration of the pramanas and then the several topics which usually obtain in debate.  Our purpose in logic is to understand the nature of reality or it is for the purpose of finding out the right method by which we may extricate ourselves from sorrow.  The first would properly be called philosophy, the second would be an ethic.  Broadly speaking these two aims are unified in Vedanta, though by and large the aim of Buddhist and Samkhyan logic is to extricate oneself from misery, that is threefold.  Though threefold it is capable of being multifold.

            2. The Buddhist and Samkhyan logics are concerned with the getting rid of misery.  Accordingly they seek to find out the cause of misery or sorrow (duhkha).  It is not so in Vedanta in the same sense.  The Vedanta holds that the Cause of the entire Universe is God, so too the Nyaya system, because the original cause is that Primal Creator of the Universe; either efficient or material or both.  This leads to certain major difficulties about the explanation in regard to the cause of the misery of the individual or of the world itself.  God becomes the cause of the individual and cosmic misery if he is considered to be the Cause.  Perhaps it is because the individuals began to place the responsibility of all evil and misery, both individual and cosmic, on God, and thus consequently felt no responsibility on their own part, the great ethical thinkers Kapila and Buddha felt that the true cause of man’s misery is to be traced to something else.  The search for cause of all creation is not capable of solving the problem of individual misery and cycle of birth and death.  Thus we can understand why these two systems became interested in the cure of the disease and therefore searched for the cause of the diseases of man, his misery and sorrows and fears, and this they affirmed is not God (indeed God does not come into this picture) but desire – the desire to living in the changing world.  The basic denial of the necessity to assume God as cause of the misery of man lies behind the so called atheism of these two systems.  We can even conceive that the Purvamimansa and Vaiseshika denials of God as the Ultiamte cause of the processes of karma and dharma was somewhat due to this claim for immediate causes.  But they have less justification for avoiding God than the system of Kapila and Buddhism, for the ethical responsibility for one’s misery is laid on man or the individual soul in these systems and God is freed from this responsibility.

            3. The most important feature of the two systems, Buddhism and Samkhya, thus lies in the dynamic concept of logical thinking, that is to say, in the discovery of Casuality as the principle of discovery.  Samkhyan logic is definitely linked up with the inductive process of discovering causes and is not interested in the logic of building systems or drawing out implications from propositions.  It is real logic. Its entire sphere of logicalising or casual discovery is the sphere of organic development and experience.  If the Samkhyan system does not affirm the fact that desire is the cause of all sorrow, an aboriginal desire, it investigates the fact that there must have been an original cause for all these and it is not the God of the theists.

            4. Some basic concepts of the Samkhyan logic are propounded at the very beginning of the treatise, Samkhya Karaika.  The concepts of logical thing  center round the pramanas or instruments of right knowledge.  Pratyaksa or perception is clearly limited to the sensory organs. The Samkhyan analysis of the organs of sense and action reveals them to be the manas (which is considered to be a sense-organs of action in a sense also do contribute to enjoying and knowing as the organ of speech (eating), grasping by hand, walking by feet, alimentation and sexual enjoyment or sitting).  These sense-organs grant knowledge of the world of sounds, forms and colours, touches of soft and the hard etc., tastes and smells which are standing for the objects or elements, akasa, vayu, tejas, ap and prithvi.

            These tanmatras (sound, touch, form, taste and smell)are the signs of the gross objects, ether, air, fire-light, water and earth.

            Thus the word linga is used to designate the sign of a thing.  The sign of the element ether is sound and so on, with respect to other signs of other elements.  The inference of an element is made from its sign alone (tanmatra – that alone or that quality).  Samkhyan theory holds that the quality that is tanmatra is subtle perceptible form of the element that is gross.  Indeed since our own body is made up of these gross element that is gross.  Indeed since or own body is made up of these gross elements also, in a sense it is clear that what we have to attend to in our investigation of the causes of our misery is precisely the constitution of our physical body along with the subtle(linga from which we infer the gross to which it is related as cause is to effect).

            If all inference is restricted to the inference from cause to effect the cause will signify the presence or possibility of the effect.  The cause because of its antecedence becomes the linga and the effect is the lingi that which it signifies as following from it.  Thus the Karika states that all inference is lingalingipurvakam.  The usual translation is to make the linga, the hetu or reason, and the lingi, the probandum, that which it proves.  The deductive logic would involve the fact that smoke is the linga and the fire is the lingi.  But we cannot say that the smoke causes fire.  It is not casually used. The linga specifically is a casual term, etymologically it means that it takes one or goes to that with which it is linked or connected casually.  The presence of the cause leads to the observation of the effect.  In inference the mind moves within the casual linkage.  Linga is that close casual linkage between cause and effect so much so to observe the one or think of the one is to be led to think of the other.  Whilst this linkage between cause and effect may be effected by constantly or invariably perceiving them together both in positive cases as well as in the negative (anvaya vyatireka), yet it is possible to link the two even by a single observation which is free from all defects of omission and commission.  Dynamic casual inference is most important in Samkhyan logic.

            That is the reason why the inference is classified into three kinds; Inference from the Cause (antecedent – purvavat) to effect; (ii) Inference from Effect (consequent – sesavat) to cause; and (iii) Inference from the common qualities perceived in many effects (or causes); samanyato drsta.

            The Linga and Lingi are exchangeable that is to say the effect can be the linga or the cause can be the linga, in either case they lead to the lingi, cause or effect; this of course is logically necessity.

            Vacaspati Misra identifies the above inferences with Vita and Avita inferences in Samkhya Tattva Kaumudi-Karika 5.  But his own explanation of the two terms, Vita and Avita, are to speak the most confusing.  Vita means that which has gone – it is therefore an inference from the cause that has happened.  (If the cause is in the process of happening).  This is the purvavat anumana.  The Avita anumana would mean infernce from that which has not happened – namely, the effect to the cause – Sesavat anumana.  But it is impossible to hold that the former is anvaya anumana and the later is vyatirekanumana, that is inference based on positive or presence or agreement of cause and effect together and the latter as based on negative or non-presence of cause meaning the non-presence of effect.  Firstly the terms vita cannot be given a novel derivative root, which means excessive agreement or anvaya.  Vita means that which has been removed or gone as in “vita-raga-bhaya-krodah Sthitadhir munirucyate”.  This explanation is certainly more in consonance with the spiritof the Samkhya Karika than the attempt to find a new meaning to square it with the Naiyayika logic.  Naiyayika logic is mechanical, atomistic, static, whereas the Samkhyan logic is organic, dynamic and synthetic.

            The logic of Casuality is stated thus precisely when the Samkhyan system assumes that there is a Casual world – that is there is for every effect a cause.  This is what western logicians have assumed as the postulate of universal causation; nothing happens without a cause.  Secondly, that the casual relation is such that the cause has within it the potentiality (sign of: linga) of the effect and as such both the cause and the effect are real things or events or existents, however much they may also have the further possibility of effectuation.  Thus though the First cause has not got any other cause for its being, being original, the effects of this first cause do have in their turn effects and thus become causes in respect of their consequents.  Finally there happen effects which are incapable of being causes of other things or modifications.  In this sense the meaning of the word cause or olinga is getting restricted in this system to the twenty-two categories of causes and effects.  (The Samkhya Kartikak 3 gives the list of these; the first is cause, prakrti, this being the technical term for cause in this system, there are seven effects which in their turn are causes (vikrti is the tehnical term for effect or modification), and there are 16 vikrtis or effects which are not causes).  Thus the whole world which is shaped into all kinds of things are out of these effects.  In a sense they are not modifications of the Original Cause but inventions, creations, compounds and aggregates of these gross elements in their collective and in their atomic forms.

            Further the strict necessity and possibility of inference both from the effect (called the remainder – avita or sesa) to the cause the inference from cause to effect (vita or purvavat) involves the assumption that there is only one cause for one effect and strictly like science avoids the plurality of causes which is always the ground for doubt and tarka.  This is one of the ideals of scientific knowledge and leads to predictability.  Samkhyan ideal of explanation is thus scientific causality and avoids the usual view that there can be multiplicity of causes; at least it does not seem to accept the view that we are concerned with such causes as God, Fate, Chance and so on.  This is the meaning again of the inferences which are casually implicative, not as in immediate inferences or inferences which are non-syllogistic and non-casual or incapable of being converted into syllogistic propositions or statements.

            A still further assumption underlies the explanation of the third kind of inference; samanyato drsta. Usually this kind of inference is said to refer to analogy; argument from similar characteristics.  The similar or common character (usually known as Jati in certain systems which almost suggests thattehy had the view that the things which possessed common qualities are born from; ja; the same thing), is the reason for inferring either similar effects or similar causes.  The bovine nature of both the cow and the buffalo makes us infer that the milk of the latter is as edible and good as the former.  The presence of an identical proportion of a same quality makes us infer the nature of both to be identical.  Similarity being partial identity it is from this identity-tadatmya-that we infer the cause or the effect of two or more things, as having a similar cause.  Further this leads us to the concept of a single cause for many effects.  Thus the common quality in the several types of mankind helps us to infer the several types of mankind helps us to infer the common or single ancestor for all mankind or the common future for all mankind – the kingdom of equality for all men.  It is this kind of inference that leads us to the Single Cause or a Single destiny.

            It is thus more than analogical inference which is dependent upon the common function rather than common structure.  But both kinds of inference are valuable for difference kinds of inferences about cause and effect.

            Samyati’drsta inference is however used in Samkhya in a special way; It is said to be useful in cases of causes(or effects?) that are atindriya:; supersensuous:: which exceed the capacity of perception by the senses.  This includes even manasa extra-sensory pratyaksa.  How this can be so is seen clearly from the fact that according to Samkhya, the ahamkara or the function known as individual will or doing or agency is not an object of sensory knowledge.  Nor is intellect an object of such knowledge.  Nor is intellect an object of such knowledge.  It is one of the profound standpoints adopted by Samkhya when it affirmed that there are three pramanas and these respectively apply to effects, causes and effects, causes and to that which is neither a cause not an effect.  Thus effect or vikritis are known by perception (pratyaksa), causes are known through inference (Prakrtis are known by anumana of three kinds), the Original cause or pure Prakrti ony by Samanyato drista and the Purusa which is neither cause nor effect is known through Aptavacana or reliable testimony, that is to say, statements of those have attained that condition of knowledge of that Purusa as different from all prakrtis and vikrtis and as eternal and knowable only through Aptavacna such as those of Kapila (Buddha or the Sages of the highest caliber).

            Thus Samanyatodrsta is the inference of the supersensible from the sensible common characteristics (linga).  This may be called linga-samnya.  The perception of the common characteristic of all the sensory and motor functions is necessary; this is of course a way of discriminating the similar or the common from the dissimilar or the unique differences.  That there is difference in form and nature between the cause and effect is well known as the difference between the subtle and the gross, the distinguished and the undistinguished.  The common characteristic is seen to be at each stage implicit or resident in the cause, I-ness is the characteristic of all sensory functioning; thought seems to pervade or inhere in all the I – nesses or doings of the I and thus it in turn becomes the cause of ahamkara. That which is beyond thought or buddhi is purely inferred because it is as the very condition of all effects or thoughts that one accepts its existence.  From out of nothing nothing can come; thoughts thus imply the existence of the cause which is the cause of thought and all other effects.  In one sense the entire tree of evolution or chain or causation (pratitya samutpada or Buddhism) is implicit in this trans-buddhic entity called Prakrti, Pradhana, Avyakta and so on.

            The Samanyatodrsta inference further furnishes the fact that this original cause should contain the three kinds of characteristics called Sattva, Rajas and Tamas, steadiness, activity (origination) and tamas or rest or destruction.  Every particular effect has these three stages or characteristics of arising continuing and passing away (or dying).  Even the atoms have these processes in this system (unlike as in Vaiseshika-Nyaya).  Since these three characteristics (gunas or threads) (interwovenly) are present in each and every effect and therefore it is the samanya or common characteristic it is seen that there should be one Cause from which all these should have originated or arisen.  Indeed the most important argument for the Oneness of the Prakrti for all effects depends on this perception of the Common quality of triguna (threefold processes).  (Indian puranas and Vedanta see in the three processes, of sristi-sthiti-samhra, janmadi – the very nature of Prakrti or phenomenal existence.  Thus Samayatodrsta inference ultimately is the only manner by which the Oneness of Prakrti for all is established on the basis of the perception of the three gunas which was omnipresent in all effects, sensible and supersensible (Gods even are classified according to gunas).

            Thus inference is clearly restricted to casual implication designated by linga-lingi-puravakam.  That this might be taken to involve the concepts of vyapti (invariable concomitance) said to be the basis of all inference (anumana) need not be denied.  The basic consideration in scientific thinking, however, is this dynamic organic logic in which the effect is assumed to exist in a subtle condition in the cause and the cause is exhibited or revealed or manifested in and through its effects.

            The Samkhya Karikas definitely provide this casual necessity in their inference.

            Thus they infer the nature of the Unmanifest (Avyakta) from the vyakta (manifested).  The commonality of the three gunas is inferred by the presence of the three types of attitudes in all that is manifested but distributed more or less. The inference from effect to cause assumes the similarity and dissimilarity between the manifest and the unmanifest.  There is no attempt at all to deny that the effect is dissimilar to the cause, but the potentiality of the effect in the cause and the continuity of the cause in the effect cannot be denied at all in the field of Nature.

            The inference from the nature of the Prakrti (Avyakta and Vyakta) to the existence of the Soul or Purusa is however interesting.  The Purusa has been stated to be neither a prakriti nor vikriti, neither cause nor an effect.  If pratyaksa gives knowledge of the effects, and if anumana gives the knowledge of the causes, then Apta-vacana alone can give us definite knowledge about that which is neither cause nor effect.

            Actually the existence of the Purusa is inferred (or seems to be inferred) from the observance of the following in Nature:

(1)   the sangata or aggregation or the evolution of the body with all its different organs and limbs (Buddhistic Skandhas?) is or ought to be for the sake of an enjoyer (bhokta).

(2)   There must be a subject for enjoying the object (there must be the reverse of the trigunas); there can be no object as such without being an object of a subject.  This does not appear to mean to imply the principle that every determination implies negation.

(3)   Since there must be superintendence; in other words Nature appears as if it is for the ends of another;

(4)   There is in each self at some time or other a craving for escape from nature and its bodies.

            The above inferences reveal that the Samkhyas accepted a final cause or prayojana which is capable of being arrived at by the design and activity on the one side of Nature and on the other the inward impulse to freedom from misery or sorrow.

            The Samkhyan Kakrika (17) can be interpreted in a different way:

(1)    at the beginning it shows that the soul embarks on its terrestrial life observing that a body has been made for its in dwelling.  The entire body with all its organs is naturally got ready in the womb and it is said that the soul enters this about this period.  The sangahata is thus the 22 organed body which is ready for occupation.

(2)    This soul is of course the subject who really uses and enjoys the experiences of the world and body through the senses; sensory knowledge of the Objective World being its new experience, through fragmentary snapshorts distorted or vivarta or viparyaya of the Ultimate.

(3)    It takes delight in superintending this body with all its senses even like a charioteer enjoys driving the chariot.  This is youthfulness.  But as the soul lives on its body it begins to taste both the sweet and the bitter and finally as it ages and the organs wither or lose strength and health the soul seeks to leave the body; this leaving may be either for another body or once for al.

            The reasoning is from the observation of the individual, in his psychic introversion, rather than what it appears to be on the face of the Karika a reasoning based on the nature of Prakti (vyakta or avakta).  There is hardly any cause-effect relation here nor the samanyatodrsta possible.  Therefore, this must be one case of introversion or introspective analysis on the basis of the self-evidence of the self.

            The question is whether this can be a case of Apta-vacana;  The axioms of purpose proceed from the intelligent conscious being and are inherent in it; to transfer that to the unintelligent is a twist in reasoning.  But if we accept that there is no reasoning from Prakrti or its nature but from the Purusa, the reasoning does not show itself clearly as casual but final and this final causality rests in the soul not in prakrti.  Axioms of final causality cannot be proved but are based on actuality of experience in the world; a house is built in order to be occupied; and so on.

            The Apta=Vacana or the words of the Siddhas or those who have attained the final Goal, are reliable and it is likely that the several statements about siddhis etc., are reliable statement of the siddhas.  The argument from inner enlightenment of inner insight after one has seen through the whole evolutionary drama of Prakriti, not at the beginning.  The most basic reason for the existence of the self as distinct from nature in all its forms is the desire for liberation from the cycle of samsara, the sensory world and all that it entails by way of pleasure-pain, jaramarana etc.

            Thus apta-vacana is not easily identifiable with the Sruti, thought the whole content of the Sruti is precisely this assurance of liberation of the soul from prakrti without return punaravrtti which cannot be given through any inference or pratyaksa.  Indeed it is clear that the sensory and intellectual reasoning dependent on Nature cannot give any knowledge of that which is different from them.  Thus the knowledge of the Self or Purusa comes from itself, it is atma siddha or purusa-siddha (svaayam-siddha), and can be known only through those who have known that themselves, Samkhya has not presented this aspect but has tried to bring it under the other types of reasonings but without success.

            The corrective to this teaching is identical with the effort made against the arguments for the existence of God; God cannot be proved with the help of finite logic, that is logic limited to the experiences of the senses on which all our inferences and analogies depend.  Neither an extension of this way of reasoning nor the method of infinitising the finite or reversing of the nature of the finite and the known (technically called viprayaya in Samkhya) can be of help.

            God can be known and seen and entered into only through devotion which is the fulfillment of knowledge that He is the Ultimate Self – a knowledge which none of the other pramanas excepting Sruti grants or a age or Jnani teaches.  Similarly no one can speak about one’s experiences as existing or otherwise except oneself – it is svathah siddha.  Though the soul may go through the processes of identifying itself with each and everything yet it gives up these identifications the moment it discovers them to be different or as objects leading to suffering of one kind or another.

            Thus apta-vacana which has not been fully described in the Samkhya Karika requires a fuller appreciation in its use in the System which of course it has used.

            The whole work after establishing the tattvas proceeds as if it were description and the reasoning adopted is analogy from the world of experience.

            However, it is claimed that it is all due to the Supreme Teacher Kapila (the apta-vacanakara) that all these have been clearly affirmed as reliable doctrine.