Problems of Epistemology

The Problem of the Origin of Knowledge

Empiricism

The critique of this mathematical rationalism historically culminated in a second significant movement in the development of new philosophy: English empiricism, with John Locke and David Hume as its principal representatives.

The fundamental tenet of this movement is the distinction between two types of sciences, which differ both in essence and method: purely abstract sciences (concerned with concepts), such as mathematics, and empirical sciences, such as physics and psychology. The fallacy of rationalism lies in its exclusive recognition of a single form of science—mathematics—and its misguided attempt to model all sciences according to this scheme. This endeavor is fundamentally impossible; the sciences of facts, encompassing both natural and spiritual realms, are entirely distinct from mathematics in both content and method.

Mathematics is characterized by its avoidance of any assertions regarding the existence and functioning of the real; it engages solely in deductions from concepts. Geometry does not claim: "this figure is a circle," or "this body is a sphere with an elliptical motion," but rather states: "from the definition of a circle, certain consequences follow." Whoever accepts the definition must also accept the consequences, which are logically connected; it is entirely indifferent whether there exist actual entities corresponding to the given concept.

Conversely, the situation is markedly different for the other group of sciences—empirical sciences. Physics and psychology aim to reveal to us the workings of things that exist independently of our concepts. How can we know anything about this? Empiricism answers: only through experience. From the concept of water and heat, one cannot derive what will occur if a thermometer falls below zero or rises to one hundred degrees; from the concept of a body, one cannot develop an understanding of what happens if its support is removed. Only perception informs us that it will then fall; concepts leave us entirely helpless. Even the most perfect reason, Hume argues—Adam's reason before the Fall—would not tell him that if he fell into water, he would sink and drown; it would not reveal to him what happens when a moving body collides with another at rest. Similarly, psychology cannot deduce from the absolutely established concept of the soul that it possesses feelings and desires, that it makes inferences and conclusions, or foresee that air vibrations will produce the sensation of sound, pressure on the eye will produce the sensation of light, or a blow to the face will produce the feeling of anger. All this we know solely through experience.

John Locke was the first to articulate this perspective. He endeavored to demonstrate how all our concepts originate from experience. With more thoroughness than necessary, he attempts (in the first book of his "Essay Concerning Human Understanding") to prove that humans are not born with innate ideas—a fact that perhaps no philosopher needed to be taught, and certainly not Descartes. The real opposition of views here is as follows: Descartes maintained that in physics and psychology—just as in mathematics—it is possible to form concepts whose objective significance or truth is demonstrated by their internal possibility. Locke denies this. While the concept of a body, defined as "corpus est res mere extensa," or the definition of the soul as "mens est res mere cogitans," may be internally possible, clearly and distinctly conceivable, this does not prove their truth; one can just as clearly and distinctly imagine a golden mountain. The truth of concepts in any science dealing with facts rests exclusively on the presence of such facts and relations in observation. This further establishes that the concepts of empirical sciences cannot possess the firm closure of mathematical concepts; they remain open to expansion and transformation through further observations. The concept of gold encompasses all observations made thus far about this substance: it has a certain color, a specific density, and a particular relation to mechanical, chemical, and thermal influences. It is possible that further observation will reveal new properties; it is also possible that we will discover another substance that possesses all the properties of gold except for a melting point that lies slightly higher or lower. In that case, we would expand our concept to accommodate this deviation. In contrast, the mathematical concept is entirely closed: a figure whose radii are not equal is not a circle; a line intersecting a circle at more than one point is not a tangent. Likewise, the concepts that Descartes seeks to establish as the foundation of physics and psychology are not closed, mathematical concepts, but rather open, empirical ones. Descartes asserts: a body is a thing whose essence is exhausted by extension, while the soul is a thing whose essence is exhausted by consciousness (cogitatio), for such a thing I can think clearly and distinctly. Of course, I can; but if experience now shows me that the same entity that is extended also thinks—in certain cases, at least—or that the very same being that thinks also moves material masses, could I then not also think this? Would it still be appropriate to adhere to the definitions provided above? Clearly not—these would be concepts inadequate to encompass the facts as they exist. Thus, all empirical concepts are open concepts; they are in a state of constant motion, adapting more accurately to the world of observable facts. With such concepts, the demonstrative method, as applied to mathematical concepts, is impossible.

Locke frequently emphasizes: the formally most perfect knowledge is mathematical knowledge. He laments the narrow confines of this mode of knowledge, which he considers possible only in morality alongside mathematics; however, we must acknowledge that empirical sciences, such as physics, chemistry, and psychology, do not permit discussion within this framework: observation and experience are necessary here.

David Hume adopted this view and carried it to its logical conclusion. The central focus of his brief, straightforward, yet profound "Enquiry Concerning Human Understanding" is the investigation of the concept of cause and effect. The law of causality has always been a cornerstone of rationalism; it was assumed that one could derive the effect from the concept of the cause; the relationship of cause and effect is akin to that of foundation and consequence, sequi = causari. Hume demonstrates that this is a misconception; drawing conclusions based on the law of causality is something entirely different from making inferences based on the logical law of contradiction. The relationship of cause and effect is not, in general, a logical relationship that could be comprehended through pure thought. In physics and psychology, cause and effect refer to phenomena that are in a relationship of constant succession over time. The perception of temporal succession is the only thing that is genuinely observed here; the internal connection between phenomena, the necessity that binds them, is at least not an object of observation. I perceive that one phenomenon follows another; I expect that the same phenomenon will be followed by the same other phenomenon next time: this is the beginning of causal understanding. We find this also in animals, and experience enhances their intelligence; the process occurs as follows: from the perception of a sequence of events, the repetition of the first event leads to the expectation or anticipation of the second. In humans, this relationship is further developed; not every perceived succession compels us to anticipate its recurrence; we gradually learn to distinguish constant successions of phenomena from random and fleeting ones; yet the fundamental basis remains the same. Through logical inference from the concept of cause, one cannot derive the effect. Take the simplest example: the motion of a body during a given time interval is the cause of its motion during the next time interval; this cannot be derived through logical inference in any way. From the premise that "this body is moving at a certain speed and direction at this second," logically nothing follows except the falsity of the converse, but nothing regarding what will happen in the next second. I expect, based on prior observation, that this body will travel the same distance in the next time interval, at the same speed and in the same direction. However, this expectation does not possess logical necessity, akin to any mathematical proposition. I could also think that the motion—whether suddenly or gradually—might cease on its own or change direction in some way. Prior experience correctly revealed the manner of action that we articulate in the law of inertia; but it is not a logical necessity that the future must resemble the past. In general, Hume asserts (and this is the most general formulation of his view), there does not exist a single fact whose nonexistence is not conceivable or logically possible. The nonexistence of any body, the invalidity of any law of nature is conceivable, for even the nonexistence of the world itself is also conceivable.

From this, it follows that in the empirical sciences, such as physics and psychology, there exist no universal truths in the strictest sense. Instead, there are only presumptively universal propositions, each of which carries with it the self-evident qualification—pending correction by subsequent experience. The propositions of mathematics are universally and absolutely true; no observation can shake or alter the assertion that the sum of the angles in a triangle equals two right angles; this assertion is posited as a logically necessary consequence by its very nature. In contrast, there is not a single proposition in physics or psychology that possesses such necessity. Even the law of causality does not stand as an exception; it is merely a presumptively true proposition, positing that a strict regularity governs the succession of natural phenomena.

It is conceivable, and logically possible, that phenomena may occur that are entirely unrelated to all preceding and subsequent occurrences. Such phenomena we would designate as miracles. Therefore, miracles are undoubtedly possible; in our reasoning, they are as conceivable as facts that can be explained by our natural laws—that is, facts that can be systematically included in the framework of the natural order. The question at hand is not one of possibility but of actuality: have there truly been occurrences that ought to be considered as miracles?

David Hume raises a resolute skepticism against this assertion: in his view, the assumption that so-called miracles can be explained, if not physically, then at least psychologically, carries such a high probability that it can practically be equated with certainty. We have so often encountered that human testimonies are grounded in deception, whether intentional or unintentional, that it seems far more plausible to attribute any claimed miracle to this than to abandon the fundamental presumption of our entire inquiry: the regularity of natural connections. This presumption, of course, is not logically necessary, but it has been so thoroughly corroborated by facts and so frequently confirmed, even with respect to purported miracles, that we have every right to approach new claims of miracles with a priori skepticism.