In this section, I would like to draw special attention to the epistemological problem of perception versus inference, and the bearing it has on the respective metaphysical theories of Hume and Carvaka[i]. There exists a basic similarity between Hume and Carvaka in that for both thinkers theory of perception form the basis of their skepticism on many related matters such as substance, assumptions about the nature of causality, status of the causality, status of the external world and belief in the supernatural and other related issues. For the sake of clarity, this section of my paper is further divided into four parts. The first part provides a brief explanation of the importance of the relation between impressions and ideas in Hume's epistemology. The second part discusses the status of the world independent of consciousness in Hume and Carvaka. The third part discusses the question of how the Carvaka arrived at the view that the knowledge can be obtained from perception only, and the question of the relationships between perception and inference in Hume and Carvaka. The fourth part analyzes the striking parallel between Carvaka’s and Hume’s treatment of causality.
In the Treatise, Hume begins his study of the human understanding with a careful investigation of the contents of our minds. In the opening lines, Hume gives us a classification of what he call “perceptions of the human mind”. He holds that “everything which appears to the mind is nothing but a bundle of perception”, and that “to hate, to love, to think, to feel, to see; all this is nothing but to perceive”.[ii] He then divides the perceptions of the mind into impressions and ideas. An impression for him is the immediate datum of experience: for example, sensations, passions, as they make their first appearance in our minds. An idea, for Hume, is a “faint copy of an impression.” These ideas and impressions always correspond to each other. In other words, there can be no idea in our mind, if we do not have a corresponding impression; a blind man cannot have any notion of color, nor a deaf man sound. He makes a further distinction between simple and complex impressions and simple and complex ideas. However, the important distinction between impressions and ideas is that the former appear first in consciousness and the latter are copies of the former. All knowledge is derived from impressions and the way to ascertain the truth of any simple or complex idea is to trace its origin to the impression or impression from which it is derived.
This relationship between impression and ideas is very important in Hume’s philosophy. His purpose is to show that we cannot have any idea corresponding to which there is no impression. For example, he asks, from what impression the idea of substance is derived? And, he concludes that we have no idea of substance apart from the idea of a mere collection of particular qualities. He states: “When we entertain, therefore, any suspicion that a philosophical term is employed without any meaning or idea (as is but too frequent), we need but to inquire, from what impression is that supposed idea derived? And if it be impossible to assign any, this will serve to confirm our suspicion.”[iii] Thus, Hume rejects the notion of substance, whether material or spiritual.
The Carvaka philosophers, like Hume, stressed the validity of perception as the main avenue of knowledge. As such, they thought that only the four elements, earth, fire, water, and air constituted the whole of reality for these and only these are the things we perceive. The infinite variety in this world is explained by different combinations and proportions of the four elements. Mind, as well, is but a certain ordering of earth, water, fire and air. This emphasis on perception has its parallel in the importance Hume puts on impressions. Just as Carvaka would deny the existence of anything which cannot be perceived, in the same way, Hume would deny the meaningfulness of an idea which cannot be broken down into its constituent impressions. However, it is obvious that there is a great difference in the point of view between the two positions. The Carvaka is making a sweeping metaphysical claim, while Hume is making an epistemological claim. In this sense, the Carvaka is more optimistic about man’s capacity for knowledge. Although our knowledge is limited by what we can perceive we nevertheless can perceive the only reality namely, matter, whereas Hume’s epistemological point of view claims it is impossible for us to know things in themselves. One never comes into contact with the physical object, but only with the impressions of what we believe to be caused by physical objects. This is not to suggest that Hume outrightly denies the existence of external physical objects. Rather, he is denying that our natural belief that objects exists outside of consciousness is philosophically defensible. Hume, unlike Berkeley, did not begin with the intention of denying the existence of the objective world independent of human consciousness and perception but nevertheless reached the same conclusion. In his words:
Nature has not left this to his choice, and has doubtless esteemed it an affair of too great importance to be trusted to our uncertain reasoning and speculation. We may well ask, what causes induces us to believe in the existence of body? That is a point, which we must take for granted in all our reasoning.[iv]
In summary, for Hume there is no rational justification for saying that bodies or things have a continued and independent existence external to us.
Let us now consider the question of how the Carvakas arrive at the view that knowledge can be obtained only by perception. They argue for perception by a process of elimination. Indian philosophers generally recognize four sources of knowledge – perception, inference, verbal testimony and comparison. The Carvaka claims to have shown that the last three means have serious defects and, therefore, perception is the only valid source of knowledge. They reject inferential knowledge because for a valid inference to be possible, the truth of the universal connection must be established. From a statement like “if A exists then B exists”, we cannot infer B’s existence on the basis that we know that A exists unless A and B are universally connected. In concrete terms, we cannot say that it is going to rain by perceiving black clouds and rain are invariably related. But how, the Carvaka asks, is the universal connection known? As perception is confined to the present we cannot perceive universal connection. The senses give us only the particulars. In order for us to infer the one from the presence of the other, we must apply it to the past (experiencing its similarity with the situation), present as well as to the future and on this make a prediction the mind perceives the universal connection because the mind cannot perceive external objects like clouds and rain except through the sense-organs. Nor is it correct to claim that we can establish universal connection by inspecting a large number of cases in which we perceive a connection between things, since there is nothing which necessarily prevents a failure of connection in the future, that is, incongruence with the past experience. In summary, the existence of inference as a source of valid knowledge is equally unfounded, as the essential condition for the possibility of inference cannot be established.
Hume derives the content of his skepticism on the basis of his analysis of the limitation of sense-perception. He shows that all our ideas, simple or complex, can be reduced to original impressions. The idea of the ‘golden mountain’, though not derived directly from experience, is formed by combining the idea of a ‘mountain’ with the idea of ‘gold’, both of which are objects of experience. The Carvaka also wants to claim that objects of experience, in whatever combination, can be the only objects of knowledge. However, the Carvaka do not give an adequate account of the multiplicity of experience, for surely, perception alone does not tell us that everything we experience is composed of either earth, water, fire and air or any combination thereof. Only on the basis of perception one would naturally make a very important distinction between the four basic elements in Carvaka ontology and the human body. Nothing in the unaided perception can persuade us that there is an underlying identity between the human body and these elements. Hume’s point of view, it should be obvious, avoids this difficulty. There are, of course, difficulties of a different sort in Hume’s position, but I will not discuss them here as they do not fall within the scope of this paper.
The Carvaka’s criticism of inference is quite similar to Hume’s criticism of causality as a necessary connection. True to his method, Hume accounts for our idea of causal necessity as purely a result of certain experiences. We say that A causes B because A and B are always experienced together as either temporally or spatially connection with one another. Hume, like the Carvaka, rejects the notion that because two things have always been experienced together that they must necessarily be so connected. He says:
If we define a cause to be an object precedent and contiguous to another, and where all the objects resembling the former are placed in a relation of priority and continuity to those objects, that resemble the latter, we may easily conceive, that there is no absolute or metaphysical necessity, that every beginning of existence should be attended with such an object[v]
Hume and the Carvaka are therefore in complete accord in their skeptical views on necessary connection in causality. The Carvakas, like Hume, assert that necessary connection cannot be established even by the observation of several instances because by observing several instances we cannot know that there is no smoke in the absence of fire. However, as for the problem of the origin of this idea of necessary connection, Hume and the Carvaka give very different answers. Hume argues that this is a false idea by stressing the subjective elements of our ideas. The constant conjunction of two things is the objective element of our experience, while necessary connection is the subjectively contributed element. As with the belief in the external and independent existence of objects, the belief in a causal necessity is a natural belief but one which is found to be without any real empirical justification. The Carvakas, on the other hand, naturally did not accept this kind of explanation of false idea, as one of their central concerns was the refutation of the idea of a universal moral law which states “as you sow, so shall you reap.” According to Carvaka, the best way to refute this idea was to undermine its basis presupposition, namely that there is a necessary connection between one’s status (or condition) in this life and one’s karma as accumulated from previous lives. To admit that the idea of causal necessity has at least a subjective base would obviously not have served the Carvaka’s claim. Such an admission would have conceded entirely too much to the opposition. They wanted to prove the falsity of Vedic religion not simply its unjustifiability. But then the problem remains: how to account for the origin of false ideas? Hume posits a kind of natural disposition in human nature to account for them. However, he does not call them false ideas but merely empirically unprovable one. The Carvakas, on the other hand, and this is perhaps the most salient difference between Hume and Carvaka, is quick to assign a more insidious cause to false ideas. Any opinion which is not in conformity with what we directly experience is either due to a deliberate and selfishly motivated distortion of experience or else the result of some kind of gross mental deficiency. But in no way is it natural to believe in things which are not met within sense-perception, if ‘natural’ is taken to mean psychologically natural in Hume’s sense.
The Carvaka emphasis on the validity of sense-perception is primarily a way of combating the kind of inferential knowledge needed to support spiritualism. These ancient Indian skeptics do not seem to have been troubled by the problem which preoccupies Descartes in his First Meditation. Although the Carvaka is aware of the limitation of knowledge derived from the senses, they do not give a thoroughgoing critique of knowledge as such. They simply assume that what the senses immediately represent to us possesses external physical reality. The materialism of the Carvaka School, then, has a touch of what is sometimes called naïve realism. In this connection, the term ‘lokayata’, the Indian equivalent for materialism, is especially interesting. One of its meanings is “prevalent in the world or the opinion of the common people”. It would seem then, that naïve realism or the intuitive belief in the existence of objective reality is not solely a western phenomenon. However, Indian materialism is much more than common sense speaking the language of philosophy. In the first place there is no hint of dualism in it. Not only is the physical world real, but anything which is not physical is unreal. In the second place, although the Carvakas do not go so far as to turn skepticism on the presupposition of materialism itself it is unique in disposing, solely by the use of logical arguments, the major alternatives to materialism. But, again, a notion which the Carvakas did not entertain and one which Hume did, is the possibility of complete ontological skepticism, at least in its theoretical aspect. However, in terms of its practical application the Carvaka skepticism is unequalled in its consistency. Hume had many reservations about the nature of religious beliefs, but nevertheless, he seems to have had some sympathy for religion. In contrast, the Carvaka held that religion is a moral and philosophical pestilence because or ostensibly because it is faulty in its logic. So, considering its time and place the Carvaka skepticism is amazingly bold in the extent to which it criticizes Vedism and without any doubt much bolder than the skepticism of Hume.
In conclusion, we can see that Hume’s skepticism is making a much stronger claim about the impossibility of valid inference than Carvaka. Although Carvaka accepted perception as the primary source of knowledge, they did not want to claim the impossibility of knowing the nature of things. They rejected not only verbal testimony, comparison, as a source of valid knowledge but rejected inference as well. However, their skepticism contains an important inconsistency: on the one hand, they maintain perception to be the only source of valid knowledge, but, on the other, also assert that everything is composed of earth, water, fire and air, which cannot be known from perception. That is why some materialist like Purandara allowed inference, but only from what is perceivable to what is also in principle perceivable. In contrast, Hume denies the possibility of knowing the thing in itself independent of experience, which is the result of his extreme idealistically oriented empiricism. He state:
Now since nothing is ever present to the mind but perceptions, and since all our ideas are derived from something antecedently present to the mind, it follows, that it is impossible for us so much as to conceive or form an idea of anything specifically different from ideas and impressions.[vi]
Thus, the mind does not have anything present to it except perception and therefore cannot experience any universal connection between objects. The assumption of such a connection, for Hume, does not have any rational foundation. He admits limited skepticism as both “durable” and “useful”. By questioning the soundness of popular notions, the skeptic sets new problems, directly supplies different fresh philosophical problems and saves philosophers from dogmatism to a large extent. On the Indian scene, for example, the influence of materialism was considerable at one time and both the astika and nastika schools took great pains to refute the Carvaka materialism and skepticism before proceeding to establish their own view. In Western philosophy Kant states, “I openly confess my recollection of David Hume was the very thing which many years ago first interrupted my dogmatic slumber and gave my investigation in the field of speculative philosophy a quite new direction.”[vii] However, Hume rejected excessive skepticism of the Jayarasi type as untenable in practice. He writes:
Fore here is the chief and most confounding objection to excessive skepticism, that no durable good can ever result from it while it remains in its full force and vigor. We only ask such a skeptic, What his meaning is? And what he proposes by all these curious researches? He is immediately at a loss and knows not what to answer.[viii]
I would contend that although Hume correctly noted the danger of extreme skepticism of the Jayarasi type and made a distinction between his own skeptical outlook and extreme skepticism, his own skepticism presents as great a threat to philosophy. Though Hume believes from the standpoint of common sense that an independent world exists outside of our minds his epistemological skepticism rules out the possibility of our mind “really” knowing objects external to us, which forces him to concede that this system leaves open the possibility of solipsism, the impossibility of disproving religion and, most importantly, the impossibility of obtaining objective knowledge.
 In this section of the paper the term “Carvaka” will be used synonymously with materialism
[ii] David Hume, A Treatise on Human Nature, edited with an analytical index by L.A.Shelby-Bigge (Oxford: Clarendon Press, 1888), P. 67.
[iii] David Hume, An Inquiry Concerning Human Understanding, edited with an introduction Charles W. Hendel (Indianapolis: The Bobbs-Merril Company, Inc., 1975), p. 30.
[iv] Treatise, p. 187
[v] Ibid., p. 172
[vi] Ibid., p. 67
[vii] Immanuel Kant, Prolegomena to Any Future Metaphysics, with an introduction by Lewis White Beck (Indianapolis: The Bobb-Merrill Company, Inc., 1976), p. 8
[viii] Inquiry, p. 168