Again, if things were held to be existent in an absolute sense, that is to say, if existence were their only characteristic and non-existence were denied as ideal fiction, the result would be equally disastrous. There would be no distinction of one thing from another. Everything would be everything else having nothing to distinguish them. Secondly, there would be neither beginning nor end for anything. Thirdly, nothing would be possessed of an individuality. In other words, things would be nothing - entity would be reduced to non-entity. We propose to demonstrate how the absurd issues alleged above follow inevitably on the denial of non-existence as a characteristic feature of things. Now, non-existence is recognised to be of four types, viz., (i) absolute non-existence, e.g., the nonexistence of colour in air (atyantābhāva); (ii) pre-non-existence, e.g., the non-existence of the effect in the cause (prāgabhāva); (iii) post-non-existence, e.g., the non-existence of an effect after destruction (pradhvaṁsābhāva); and (iv) mutual non-existence or numerical difference or non-existence of identity of things (itaretarābhāva). If existence were the whole nature of things, there would be no non-existence anywhere; and in the absence of the fourth type of non-existence, all entities would be lumped together into one thing, viz., Existence. The Sāṅkhya does not believe in the reality of non-existence. But in that case the enumeration of the different categories and the evolution of the categories from primordial Prakṛti in a descending scale and the dissolution of each succeeding category into its immediate predecessor would have no meaning. The existence of a second entity implies that the first is distinct and different from the second and this presupposes the reality of mutual non-existence. The emergence of lower and later categories from the preceding ones presupposes that they were not existent before at least in their developed form. The presupposition of such unprecedented emergence is the second type, viz., pre-non-existence. And the retrograde course of evolution, in which the lower categories are said to be re-absorbed into the higher one, presupposes that they cease to exist at any rate in their finished form. This presupposes the third type of non-existence. And the non-existence of Primordial Matter (Prakṛti) in the Spirit (puruṣa) and of the latter in the former is evidently an admitted fact, and this necessitates the postulation of the first type of non-existence. Thus, non-existence cannot be denied by the Sāṅkhya without stultifying the whole scheme of ontology propounded by him. But the Sāṅkhya might maintain that the denial of non-existence on his part does not entail these consequences. He does not believe in the reality of non-existence apart from and independent of the reals as the Vaiśeṣika does. The denial of non-existence thus amounts to the negation of independent non-existence. But if non-existence be regarded as a formative element in the nature of reals he would have no objection to its reality with all its four varieties. But this is also the position of the Jaina and of the Mīmāṁsists. If, however, such be the position of the Sāṅkhya and the Mīmāṁsist, they should no longer characterize reals as existent only. Things, on the contrary, should be characterized as existent-and-non-existent. What the Jaina objects to is the uncritical, simple characterization of reals in terms of existence as opposed to nonexistence. The nature of reals is always a complex of existence-cum-non-existence. As regards the affirmation of non-existence as a separate and independent category by the later exponents of Vaiśeṣika philosophy, the Jaina, too, does not subscribe to it. According to the Jain nonexistence is as much an element in the constitution of a real as existence is. Accordingly a real can be said to exist or not to exist. The predication of existence and non-existence in respect of the same subject, though under different circumstances, is proof of the dual nature of reals.
But the aforementioned consequences of the denial of nonexistence would not affect the validity of the position of the Vedāntist. The Vedāntist denies all difference and distinctions. The plurality is only an illusory appearance called into existence by the inherent nescience of individual selves; there is no plurality of selves either. The difference between self and non-self is also a fiction. But the question may be legitimately posed to the Vedāntist: 'How would you establish your position? You deny all differences, but by what instrument of knowledge would you substantiate your denial? Certainly not by perception, nor by inference, nor by scripture, as all these instruments of knowledge record only positive findings. The Vedāntist, however, does not bank upon any one of these accepted instruments of knowledge. He maintains that the non-existence of difference is only a necessary deduction from the failure of the opponent to establish the existence of difference. All the arguments that can be advanced by the opponents would be shown to be inconclusive. After all, the experience of plurality is the sheet-anchor of the opponent. But this experience of plurality is not incompatible with the unity of the Absolute Brahman, which is divested of all differences, intrinsic and extrinsic. Consciousness, undifferentiated into modes and attributes, is the only reality, and experience of plurality is only an illusion. It is common knowledge that space is one and devoid of all differences and distinctions taken by itself. But the person suffering from a defect of sight would see it divided into lines. It is a truism that this experience of linear divisions in space is only an illusion. So there is no inherent impossibility in the association of plurality with the Absolute Brahman on the part of a person whose power of vision is infected with the defects induced by nescience.[1] The contention of the Buddhist idealist who believes in the multiplicity of consciousness-units has no substance. He believes in the unity of each consciousness-unit, but denies the subject-object polarization as due to the association of contents. The contents of consciousness are held to have no reality apart from consciousness. Thus when one becomes aware of blue, the awareness of blue does not establish the independent existence of blue. The 'blue' is only a content of consciousness and is non-different from it. It is due to the inherent proclivity of our thought movement for the belief in the separate existence of the content that the latter is not felt is identical with consciousness. To be more precise, the manifestation of consciousness informed with an apparent content has no raison d'être outside the separatist tendency of our thought-activity, which is the legacy of false knowledge or ignorance from which we all suffer. But the Vedāntist would urge that if the appearance of a content as an other to consciousness be only an illusion as admitted by the Buddhist idealist, then why should one consciousness be held to be different from another consciousness? The difference is felt owing to the difference of contents associated. But when contents are illusory and their association is only a false appearance, why should the difference of contents be made the ground of assertion of difference in consciousness? The difference of subject and object, the cognizer and cognized, in the same consciousness-unit is a felt fact. But still the experience of the two poles is not believed to argue a real difference in the consciousness-unit on the ground that the difference is only illusory. Parity of logic and consistency of argument demand that the difference of contents, illusory as they are, should not affect the unity of consciousness as such. Not only this. The affirmation of absolute identity between consciousness and content on the part of the Buddhist idealist would, on the contrary, make it impossible for him to meet the criticism of the Buddhist Śūnyāvādin who would deny the reality of consciousness and its content alike. If consciousness is identical with its content, which is admitted to be a false appearance, why should not consciousness also be regarded as a false appearance? Certainly between two things held to be identical, one cannot be regarded as real and the other as unreal. If a content is denied independent reality on the ground that it is never cognised outside and apart from consciousness, such also should be the case with consciousness, which is never felt apart from a content. If the variation of contents and the invariant continuity of consciousness be the proof of the superior status of consciousness, why should the Buddhist believe in the multiplicity of consciousness-units? Moreover, the relation of content and consciousness cannot be regarded as one of real identity, as the difference of content from consciousness is felt in experience. So not only identity but also difference are equally felt facts and as this is not compatible with real identity, the relation is held to be one of illusory identity by the Vedāntist, since identity-cum-difference is according to him a contradiction in terms. And illusory identity of different contents thus cannot split up the identity of consciousness.
The Vedāntist would thus successfully deny the reality of non-existence, as the absurdities alleged are not regarded as absurdities, but as a true estimate of things. The Vedāntist also banks upon the failure of the opponent to prove the reality of difference and other types of non-existence which are the presupposition of plurality. But this is not his only resource. He maintains that there is no proof in support of the reality of non-existence. If perception were competent to envisage non-existence, there would be no occasion for taking note of existence. For one existent there is an infinite number of non-existents pitted against it. For instance a pen is one entity, but the number of not-pens is practically infinite. If one were to perceive the non-existence of not-pens in order to perceive a pen, there would be no occasion for the realization of the latter perception, as the percipient would be occupied for all his life with the perception of the non-existence of not-pens, whose number is admittedly unlimited. It might be contended against this argument that the mode of perception as observed does not lead to any such consequence. The non-existence of a thing is perceived only when the negatum in question is recalled. So only those things are cognized to be non-existent, which are recalled by the percipient on the occasion. As he does not recall all the possible things that are non-existent on the occasion of perceiving the non-existence of a particular fact, but only the negatum whose non-existence is the object of perception, the charge of infinite number of perceptions of non-existence falls to the ground. But the Vedāntist would not accept the explanation, which makes perception dependent upon memory. Moreover, perception, dependent upon memory, would not give a novel experience.
The Vaiśeṣika, who believes in the perception of non-existence, would assert this amounts to a refusal to face the evidence of the psychology of perception as a whole. There are cases of perception which are independent of the services of memory, no doubt. But the perception of a thing as conducive to the attainment of a desired end is certainly dependent upon, and preceded by, memory. One perceives a mango in the dish and at once proceeds to eat it. This is made possible only by the memory of the sweet taste of mangoes experienced in the past. The perception of non-existence, as it occurs to a man of extraordinary powers acquired by the practice of yoga, is certainly independent of the aid of memory. The mystic would see everything, existence and non-existence both, in one act of intuition. But by a person of limited powers like us non-existence can be perceived only with the aid of memory. So there is no difficulty. But this defence has not satisfied the Vedāntist. In the first place, he maintains together with the Buddhist that perception is never a judgment. Perception gives us the knowledge of a thing as it is, uninterpreted by concepts. But the perception of non-existence would be a judgment as it is always cognized as non-existence of this or that. In the second place, the memory in question may be either of the negatum or of the non-existence. On the latter alternative, there would arise a vicious infinite regress. If the knowledge of non-existence be a case of memory, it would necessitate the postulation of a previous knowledge of non-existence. But as the latter would also be equally an act of memory, there would be no end of recollections. If, on the contrary, the cognition of non-existence at any stage is accepted to be independent of memory, why should the cognition under consideration be made dependent upon the same? If, however, the recollection of the negatum is made the condition of the perception of negation, that also would give rise to a difficulty in another direction. Recollection, implicit or explicit, is certainly found to be an aid in the case of recognition. Here the object of perception is remembered to have been seen in the past and is then cognized to be identical with the perceived object. In recognition the two objects are same or similar and so memory is of help. But in the case of perception of non-existence one thing, viz., the negatum, is recalled and another thing, viz., its non-existence, is perceived. So the two situations are not similar. It should be recognised that perception is concerned with existent things and so cannot have jurisdiction over non-existence. The perception of non-existence is thus a false belief. Not only is non-existence incompetent to be perceived, it cannot be known by inference also. Non-existence is a non-entity and as such has neither an effect nor a characteristic, on the evidence of which it could be inferred. The absence of perception of a perceptible is held to be the source of such knowledge. But this is also a pretence. What is seen is the empty locus and this is believed to be the knowledge of non-existence. The knowledge of nonexistence in all cases is found on analysis to be an intellectual construction arising on the perception of something else; and as the independent existence of non-existence is only a contradiction in terms such intellectual constructions are to be definitely recognized as unfounded illusions.