Main Philosophical Directions

Directions of Epistemological Theory

Pure Empiricism

The emptiness of Locke's arguments was highlighted by Berkeley, who pointed to the arbitrariness of distinguishing between knowledge derived from sensation and that acquired through intuitive understanding, as well as the impossibility of establishing any objective fact based on the arbitrary and, in any case, inconsistent agreement among various sensory impressions. Since all our sensations are given to us intuitively and thus represent subjective states, it is difficult to understand why certain sensations must necessarily be related to objects. Consequently, neither sensations nor proof can yield an objective existence; the distinction between primary and secondary qualities is baseless; only intuitive certainty is granted: the actual objects are our representations. The assumed external causes of these representations, the quality-less matter and its movements, are philosophical fictions; in our experience, there are no universal concepts, the assumption of which is necessary when positing a homogeneous substance and its causality. Therefore, firmly proclaiming the law that only the concrete singular is real, this new empirical direction certainly transcends its predecessor, which, adhering to its rational principle, attributed objective reality to concepts of substances and causality as applied to natural phenomena. A consistent pursuit of this perspective would ultimately lead Berkeley to recognize an exclusively subjective reality contained within our individual representations. However, such a recognition would contradict the objective experience of life, which undoubtedly differentiates between subjective and objective contents of experience; for instance, the latter does not include dreams, hallucinations, and the like. Thus, Berkeley sought to define the criterion employed in such distinctions by practical life experience, believing he could find it in the potential for shared perceptions among many individuals. Accordingly, he considered as objectively significant that content of experience which could pertain to both ourselves and our close associates, while subjective content was relegated to that which exists solely within our individual consciousness. Yet, this criterion, even in the formulation provided by Berkeley, revealed its inadequacy: it acknowledges as objective not only those representations that are genuinely common to many people but also those that exist only in our individual consciousness, which provide grounds to conclude that they would equally arise in others under similar conditions. In any case, the sign based on common belief among people proves to be secondary; precedence must be given to those initial grounds that compel individuals to differentiate the objective content of experience from the subjective, stemming from the previously experienced individual experiences. But even if Berkeley attempted to delve into these foundational grounds, he would never find positive criteria for objective certainty. First, the belief of many individuals in the commonality of an experience, or even an individual’s conviction that others could have had the same experience under similar conditions, is insufficient for reliably establishing the objective validity of a fact. Secondly, the mentioned criterion, even in those cases where it proves adequate, can never extend beyond the realm of practical life experience, from which it was drawn; upon the first attempt at scientific application, it must be abandoned. In natural science, there are compelling reasons not to attribute such properties as sound, color, heat, etc., directly to the objects themselves, even though they are perceived by all individuals. Thus, the mark of the common origin of experiential content has not only proved evidently inadequate as a criterion for objective existence, understanding the latter as scientific experience, but also false: it deliberately neglects all scientific experiences that, through physical and physiological analyses of phenomena, compel acknowledgment of certain elements of phenomena as subjective. This was prompted in Berkeley by the one-sidedly psychological perspective of his inquiries, which simultaneously embroiled him in fruitless polemics with the natural science of his time, grounded in mathematical foundations. As a result of such a sharp departure from the scientific method of investigation, Berkeley himself, in explaining the emergence of general representations possessing objective significance, was compelled to accept metaphysical panpsychism, that is, the community of all spirits within an infinite intellect. Thus, in the end, even in opposition to the viewpoint of common life experience, he could assert the principle of pure empiricism, only resorting simultaneously to the aid of thoroughly transcendental metaphysics.

Similar to Berkeley’s subjectivism and psychologism, the subsequent second attempt to ascend from Locke's premises to pure empiricism—sensualism—soon met with failure. It relied on the already acknowledged law by Locke that all knowledge begins with impressions from external senses, but it further posited the assumption that, as a result, all content of knowledge could be decomposed into external sensory impressions and their connections. Given that impressions and their connections are objectively given empirical facts, the pursuit of these premises seemed to lead to pure empiricism. However, this pursuit proved untenable in two respects, as clearly demonstrated by one of the most significant attempts of this kind, the theory of knowledge of Condillac. First, it remains unclear how consciousness comes to attribute sensations, presumed here as initially subjective states, to external objects. Condillac sought to justify this transition from the sensing subject to the sensed object on the special quality of tactile sensations, which simultaneously relate to subjective states and external objects; through association with tactile sensations, other sensations—such as those of sight, smell, etc.—are also objectified. The assertion that, in tactile sensations, the representation of the objective object already belongs to the sensation evidently presupposes the resolution of the underlying unresolved problem: it has not been clarified how our consciousness, through its subjective sensations, comes to knowledge of objects, yet it is claimed here that sensations themselves already contain the knowledge of objects—an assertion that reiterates, albeit in a slightly altered form, Locke's arbitrary assumption of specific knowledge through touch. Secondly, Condillac could only carry out his supposed derivation of processes of knowledge from sensory sensations through a series of sleights of hand, essentially assuming certain intellectual processes within the external corresponding causes he attempted to explain. This is clearly confirmed by his example of a statue that, initially devoid of sensations, gradually acquires the ability to use its various senses. For instance, he asserts that if a statue endowed with the sense of smell happens to be subjected to a greater influence from one olfactory impression than from another, it will respond more to the first than the second, thus relating to it with greater "attention"; he then explains that each impression must leave a trace in the soul, i.e., a memory, which upon the repetition of similar impressions evokes "comparison" and "judgment," etc.; from what has been said, it is clear that these functions of attention, memory, and understanding are not derived from sensations but presupposed as primary functions of knowledge that are activated by sensory stimuli. Thus, the attempt to articulate pure empiricism in the form of sensualism failed because it silently incorporated two a priori auxiliary assumptions: first, it was assumed that every tactile sensation inherently contains knowledge of the existence of an external object; second, various intellectual functions were directly presupposed for understanding and linking sensory impressions. These auxiliary assumptions evidently lead to a metaphysical presupposition upon which the entire theory of knowledge we are examining is built, a presupposition of the existence of an extended external world that acts on our external senses, most immediately on the sense of touch, and of a thinking subject that stands in opposition to this external world. Just as Berkeley's background included a community of spirits established by an infinite intellect, here Cartesian dualism comes to the fore. For Berkeley, the metaphysical hypothesis must explain the universal significance of experiential knowledge; for sensualism, it is necessary to make understandable the objectification of subjective content of experience. For this objectification presupposes both a realistically existing objective world and a thinking being that processes within itself the impressions received from the latter.

At last, the theory of David Hume occupies a middle ground between Berkeley's subjectivism and Condillac's objectivism, representing a significant attempt to articulate the perspective of pure empiricism. Hume did not regard the relationship between sensory impressions and experiences of the external world as a purely subjective process, as Berkeley did; nor did he see it, as Condillac did, as an act of cognition inherently tied to sensations. Instead, he considered this relationship to be a presupposition that lacks direct certainty and cannot be proven. Consequently, like any proposition derived not from reflection but from intuition, it can only be grounded in faith rather than knowledge. Here, he openly acknowledges that the fundamental issue of empirical knowledge—understanding the objective external world in opposition to the subject—cannot be resolved from the standpoint of pure experience.

However, Hume's chief contribution to the further development of empiricism lay not in a definitive repudiation of this question, which, in its essential aspects, did not seem to him the most important since it was fundamentally practical, but rather in posing and addressing the theoretical foundational question regarding the origin and significance of the fundamental concepts of scientific knowledge. Among such fundamental concepts, Hume included substance and causality. He viewed them as empirical concepts, thereby entirely disregarding the various speculative transformations they had undergone in rationalist philosophy. Substance, in the empirical sense for Hume, is an idea associated with each object in the external world, the idea that an object remains the same even as its properties change; causality, for him, is likewise an idea tied to the sequence of phenomena, the idea that one phenomenon is a condition from which another emerges as its consequence. Both concepts, evidently, are not inherent to sensory impressions in themselves, thus distinguishing them from the belief in the existence of the external world, which rests solely upon the latter. Substance and causality are concepts arising from the processing of impressions within our consciousness. In this regard, Hume sees the necessity of drawing a distinction between impressions and ideas, the latter being reproductions of earlier impressions—a distinction not yet established by Locke, but which Condillac arrived at independently shortly thereafter in his sensationalist doctrine of knowledge. In practice, this distinction was a necessary step in the search for definitive indicators of sensations or representations that underpin the belief in objective existence. Without doubt that the belief in objective existence is founded on immediate sensory impressions, Hume considered the aforementioned general epistemological concepts to be products of the connection of ideas, thus processes arising from the reproduction of external impressions. Therefore, the fundamental question posed by Hume is: what conditions must be present in the combinations of our ideas for the formation of the concepts of substance and causality, and what, therefore, is the purely empirical content of these concepts? This question directly led to the answer that both concepts rest upon the associations of ideas, the constant formation of which is prompted by impressions. If we are given a certain number of ideas in constant coexistence, we ascribe such a connection to substance; if we receive ideas in a constant sequence, we call that connection causal: we label the preceding idea as the cause and the subsequent one as the effect. Thus, Hume identified the objective criterion of concepts in the constancy of the connections of known impressions, wherein the distinguishing characteristic of the concept of substance is simultaneity, while that of causality is the sequence of impressions. The association of ideas grounded in habit, corresponding to impressions, Hume considered a subjective process of concept formation.

In conjunction with this, Hume elucidated the purely empirical content of both scientific concepts and thus resolved the problem posed to pure empiricism. However, a question arises as to whether such a purely empirical content of the specified concepts corresponds to their actual application. In this regard, Hume's theory reveals two gaps. Firstly, it did not explain why the concepts of substantiality and causality directly determine the entire order of the distribution of experiential content before experience provides sufficient material for their formation, thereby evidently serving as a guiding principle for this very order. Kant pointed out this shortcoming, reproaching Hume for failing to demonstrate why substance and causality are not merely accidental but necessary epistemological concepts. Secondly, Hume's theory, understanding the concept of substance as a presupposition of absolute constancy and the concept of causality as a presupposition of universally valid regularity of causally connected phenomena, entirely overlooked the evolution these concepts underwent in science. Any attempt to address both gaps would inevitably lead to the establishment of specific logical criteria, compelling one to abandon the assumption that substance and cause are mere products of association grounded in habit. However, alongside such logical criteria, elements that belong not merely to pure experience but to the logical elaboration of it, thus to thought, would be introduced into the realm of knowledge. Hence, even in its most coherent form, empiricism found itself confronted with the impossibility of its realization. It must either resort to metaphysical assumptions or acknowledge rational factors fundamentally excluded by it.

Hume's developed theory of knowledge within pure empiricism had only a minor impact on his contemporary era. Natural science was hardly affected by it. In the face of numerous representatives, it remained aligned with the rational empiricism expressed in Locke's philosophy, which fundamentally corresponded to the views of Galileo and Newton. Beyond this, rational empiricism also existed in various mixtures with the rationalist philosophical currents of the time. Only a few exceptional mathematicians and thinkers, such as d'Alembert, reached a level of skepticism comparable to Hume's through their own critical investigation of fundamental scientific concepts. In this respect, d'Alembert's critique of the concept of force is particularly telling. It aligns perfectly with Hume's critique of causality and anticipates the prevailing contemporary notion of the purely descriptive nature of so-called explanatory natural sciences, predominantly in mechanics.

However, pure empiricism found further dissemination within the natural sciences during the 19th century, subsequently influencing philosophy through this medium. In the preceding period, the epistemological perspective of scientific inquiry was primarily defined by physics and predominantly by a mechanical understanding of nature. Yet, in the 19th century, physiology, particularly the physiology of the senses, emerged to the forefront. It is true that physics had long established an understanding, articulated since the time of Locke in philosophical epistemology, that sensation in itself is a subjective state; in this regard, physiology did not arrive at any substantially new conclusion. However, while physics primarily relied on the analysis of external natural processes, physiology endeavored to derive similar views from the properties and functions of sensory organs. This physiological approach found a clear expression mainly in the "principle of specific sensory energies" established by Johannes Müller. The epistemological significance of this principle lay in its considerable widening of the chasm between the objective process and the sensory representation, a distinction already noted by physics. Physics maintained that subjective sensation, while fundamentally different from its objective cause, generally maintained a one-to-one relationship with it. However, this assumption was rejected in light of the principle of specific energy, which asserts that the quality of sensation depends exclusively on the excitation of a particular sensory nerve or, as it would later be termed, a neural fiber, the elemental peripheral or central end of a nerve. The sensory nerve always responds with the same sensation, regardless of the nature of the external stimulus. Thus, the once univocal relationship transformed into a multivocal one—an outcome that, understandably, significantly reinforced the conviction of a substantial distinction between sensation and its object.

Additionally, the principle of specific energy was not merely applied to the qualities of sensation but also to their distribution in space and time. Under the influence of this principle, not only color, sound, and olfactory sensations, but also spatial and temporal perceptions began to be recognized as specific energies of particular sensory nerves. Consequently, the critique of Locke's primary and secondary qualities resurfaced, reminiscent of the endeavor once undertaken by Berkeley from his psychological perspective. While physiologists applying the principle of specific energy to space and time did not go as far as Berkeley, they accepted alongside the subjective energy of so-called spatial and temporal sensations, the objective notions of space and time. This was largely not due to a consistent application of the principle but rather as a matter of habit and the general disregard of the epistemological aspect of the problem by these physiologists.

As such, once a somewhat understandable reflection on the logical consequences derived from the established premises emerged, a skeptical direction increasingly stood in opposition to the prevailing assumptions of the existing natural sciences, grounded in rational empiricism and occasionally even metaphysical dogmatism. This direction, in turn, could only substantially return to the fundamental thoughts of David Hume, which it sought to emphasize as sharply as possible by resolutely proclaiming the subjectivity of all phenomena. This view, accidentally dubbed "phenomenalism," first permeated physics. Influenced by a habit of consistent reasoning acquired in the study of physical problems, it underwent further development within that field. Phenomenalism fundamentally ignored the question of what the actual natural processes, independent of us, are and whether they exist at all. For it, the task of natural science consists solely in "describing" as simply as possible the immediate data of our sensory experiences. The expression "explanation of nature" is dismissed, as it inherently entails a metaphysical presupposition. In attempting to describe the data of sensory experience "as simply as possible," natural science must adhere to a principle of investigation that is immanent to the human spirit and is endorsed due to its utility—the "principle of economy of thought," or as it is sometimes called, the "principle of least effort." In the mathematical formulas employed by precise physical analysis of phenomena, these are viewed solely as mechanical auxiliary means for the application of this principle; such formulas possess no intrinsic significance, independent of their utility for describing phenomena, either in their further application or initial establishment.

By designating the assumption of objective reality as a practically useful "belief" and viewing the task of science as organizing all phenomena in relation to coexistence and temporal succession, given through the association of ideas based on habit, Hume clearly characterized the perspective essentially defended by "phenomenalism." Special studies dedicated to the latest descriptions of this perspective, aiming to make it applicable to natural science, simultaneously contain presuppositions that are increasingly inconsistent with the fundamental thought of pure empiricism: they introduce into the content of experience partly hypothetical, partly a priori elements. Thus, the physiological basis of phenomenalism, the principle of "specific energy," in its broad application is partly hypothetical and partly stands in direct contradiction to experience. The actual empirical foundation of phenomenalism is the fact that individual sensory elements under different stimuli, for example, retinal elements under the action of light, pressure, and electricity, produce similar sensations. This does not hold true for all sensory elements; indeed, it has not been proven that each sensory element exclusively conditions a single sensation. The attempt to reduce the concepts of space and time to specific sensations of known elements has wholly faltered, aside from its epistemological difficulties, against the contradictions posed by so-called "nativist" theories constructed on the basis of phenomenalism. In this respect, it is telling that the pursuit of such theories necessitated the introduction of certain a priori mental activities, such as "striving" for specific spatial distributions or movements, as pure action, "actus purus," without any empirical grounding in the form of sensation or feeling.

If the "principle of specific energy" is not a generalization from experience but a hypothesis that transcends and partly contradicts it, then the "principle of economy of thought" is an entirely a priori presupposition that effectively negates the requirement for science to describe the content of sensory experience. Indeed, to objectively describe the sum of phenomena can always be accomplished only by arranging phenomena according to the actual relations of coexistence and succession. However, the "principle of economy of thought" presupposes not only formally but also materially different kinds of description, dictating a choice between possible simpler descriptions as correct. Such a choice already implies an explanation of the connection between phenomena: thus, we have here not simply a description but "explanation," and moreover one that rests on the entirely a priori position that the simplest connections for our thinking are also objectively valid. Given that, under the influence of this and similar subjective positions, history teaches us, great errors have been committed, the principle of simplicity, not to mention its a priori character, cannot be attributed a significant degree of probability.

Thus, "phenomenalism," through its return to apriorism, has completely distorted its program of objective description of phenomena; similar failures have befallen attempts made in contemporary philosophy, largely in connection with the scientific "empiricism," to construct a doctrine of knowledge based on the foundations of "pure experience." Meanwhile, in the directions of "immanent philosophy" and "empirio-criticism," those aspirations that heralded the development of pure empiricism in the eighteenth century are being revived. "Immanent philosophy" is closely related to the subjectivism and intuitionism of Berkeley; however, it gravitates even more toward the apriorism of Plato. "Empirio-criticism," in its spirit, is akin to the objectivism and sensualism of Condillac; yet, in it, there is a more immediate transition to dogmatic materialism, which, through the abstract formulas it adopts, acquires a form that outwardly distinguishes it from ancient materialism.