Philosophy of the Modern Era

Hume

David Hume (1711—1776) stands as one of the most significant philosophers because he developed the empirical philosophy of Locke and Berkeley to its logical conclusion, rendering it internally coherent yet implausible. Hume's views represent, in some sense, a dead end in the evolution of philosophy; they mark a point beyond which his thought cannot progress. Since the publication of his works, refuting him has become a favored pastime among metaphysicians. In their rebuttals, however, I have found nothing compelling, and yet I cannot help but hope that something less skeptical than Hume's system might be uncovered.

His principal philosophical work, A Treatise of Human Nature, was penned during his time in France between 1734 and 1737. The first two volumes were published in 1739, with the third following in 1740. At that time, he was still a very young man, not yet thirty, unknown, and his conclusions were such that almost all schools of thought would find them unacceptable. He anticipated fierce attacks, ready to meet them with brilliant counterarguments, yet ultimately, the work went unnoticed. As he expressed, "It came from the press stillborn." "But," he adds, "differing from nature with a cheerful and fiery temperament, I soon recovered from the blow." He devoted himself to writing essays, the first volume of which was released in 1741. In 1744, he unsuccessfully sought a professorship in Edinburgh; failing in this endeavor, he first became a tutor to a mentally ill individual and later served as secretary to a general. Armed with such recommendations, he again resolved to pursue philosophy. He condensed his Treatise, omitting its finest passages and much of the justification for his conclusions; the result was his Enquiry Concerning Human Understanding, which became more widely known than the Treatise. It was this book that awakened Kant from his "dogmatic slumber," while it seems Kant was largely unaware of the Treatise itself.

Hume also authored Dialogues Concerning Natural Religion, which he chose not to publish during his lifetime; according to his will, they were published posthumously in 1779. In his now-famous Essays on Miracles, he contends that there can never be sufficient historical evidence for such events.

His History of England, published in 1755 and subsequent years, is dedicated to proving the superiority of the Tory party over the Whigs and the Scots over the English; he did not consider history worthy of being an independent subject of philosophical inquiry. In 1763, Hume visited Paris and was enthusiastically received by philosophers. Unfortunately, after establishing a friendship with Rousseau, he became embroiled in a widely known conflict with him. Hume maintained admirable restraint during this discord, but Rousseau, suffering from paranoia, insisted on a final rupture.

Hume described his character in his obituary, or "Epitaph," as he called it: "I was distinguished by a mild disposition, self-control, an open, sociable, and cheerful nature, an ability to form attachments, an incapacity for harboring enmity, and great moderation in all passions. Even my love for literary fame—my dominant passion—never embittered my character, despite my frequent failures." All of this is confirmed by the various facts known about him.

Hume's Treatise of Human Nature is divided into three books. This division corresponds to the questions examined in the work: concerning the mind, passions, and morality. All significant and novel elements of his theories are found in the first book, which is the focus of my discussion.

He begins his Treatise with a distinction between "impressions" and "ideas." These are two types of perceptions, with impressions being those that possess greater force and intensity: "By ideas, I mean the faint images of these impressions, which are observed in thinking and reasoning." Ideas, at least if they are simple, resemble impressions but are weaker: "Every simple idea corresponds to a similar simple impression, and to every simple impression, there is a corresponding idea." "All our simple ideas, upon their first appearance, derive from the simple impressions that correspond to them and are precisely reproduced by them." On the other hand, complex ideas need not resemble impressions. We can conceive of a winged horse without ever having seen one, yet the components of this complex idea all originate from impressions. The proof that impressions arise first is drawn from experience: for instance, a person born blind has no impressions of color. Among ideas, those that maintain a significant degree of vividness compared to the original impressions pertain to memory, while others relate to imagination.

In the Treatise, there is a section titled "Of Abstract Ideas," which begins with a paragraph emphasizing agreement with Berkeley's theory that "all general ideas are nothing more than individual ones associated with a name that bestows a broader meaning and prompts the memory to recall other individual ideas similar to them." He asserts that when we have a thought of a person, it includes all the characteristics present in the impression of that person: "The mind cannot form any conception of quantity or quality without forming an exact representation of the degrees of both." "Abstract ideas, in themselves, are individual, although they can become general in their presentation." This theory, representing a modern form of nominalism, suffers from two shortcomings: one is logical, the other psychological. Let us begin with the logical objection. "Finding some similarity among different objects," Hume states, "we give all of them a single name." Every nominalist would agree with this. However, in reality, general names, such as "cat," are as unreal as the cat in general. The nominalist solution to the problem of universals, therefore, fails because it does not sufficiently apply its own principles; it mistakenly applies these principles only to "things," neglecting their application to words.

The psychological objection is more serious, at least concerning Hume. Generally, the theory of ideas as copies of impressions, as he presents it, suffers from the oversight of the uncertainty inherent in ideas. For instance, when I see a flower of a particular color and then recall its image, the image lacks precision in the sense that there are several closely similar shades of color that could serve as "images" or "ideas," using Hume's terminology. It is incorrect to say that "the mind cannot form any conception of quantity or quality without forming an exact representation of the degrees of both." Suppose you saw a person whose height is 1.85 meters. You retain an image of him in your memory, but perhaps he could just as easily resemble someone who is a centimeter taller or shorter than him. Uncertainty differs from generalization, but it possesses certain similar characteristics. Yet, failing to recognize this, Hume encountered a dead end that was not necessitated by any requirement, such as regarding the possibility of imagining a shade of color that you have never seen and that lies between two closely resembling shades that you have seen. If these two shades are sufficiently similar, then any image you can create will be equally applicable to both of them, as well as to the intermediate shade. When Hume asserts that ideas arise from impressions which they precisely reproduce, he transcends what is psychologically true.

Hume banished the concept of substance from psychology, just as Berkeley had earlier expelled it from physics. He asserts that there is no impression of the self, and thus no idea of the self exists. "As for myself, when I intimately delve into what I call my 'I,' I invariably encounter some particular perception—of warmth or cold, light or shadow, love or hatred, suffering or pleasure. I can never seize my self apart from perception, nor can I discern anything other than some perception." Perhaps, he ironically concedes, there might be some philosophers capable of perceiving their own self; "but, setting aside such metaphysical speculators, I dare assert regarding other individuals that they are nothing more than a bundle or collection of various perceptions, succeeding one another with incomprehensible rapidity and existing in a constant flow, in perpetual motion."

This renunciation of the idea of the self is profoundly significant. Let us closely examine what he claims and how effective it is. First and foremost, my self, if such a thing exists, is never perceived; thus, we cannot possess any idea of it. If we accept this argument, it must be formulated with precision. No one perceives their own brain; however, each person, in the truest sense, possesses an idea of it. Such "ideas," derived from perceptions, logically do not belong to the primary stock of ideas; they are complex and descriptive. This must be the case if Hume's principle, which asserts that all simple ideas arise from impressions, is correct. Should we reject this principle, we would be compelled to return to "innate" ideas. Using contemporary terminology, we could say that ideas concerning unperceived things or phenomena can always be defined based on perceived things or phenomena; thus, by substituting definitions in place of the defined term, we can always articulate what we know empirically, without introducing any unperceived things or phenomena. Regarding our current issue, all psychological knowledge can be articulated without invoking the "self." Moreover, the "self" as defined cannot be anything other than a collection of perceptions, rather than a new simple "thing." I believe any radical empiricist must agree with Hume on this point.

From this, it does not follow that the simple self does not exist; it only implies that we cannot know whether it exists or not, and that our self cannot enter into any part of our knowledge except as a collection of perceptions. This conclusion is vital for metaphysics, as it frees it from the last remnants of the usage of "substance." It is important for theology, as it obliterates any presumed knowledge of the "soul." It holds significance in the analysis of knowledge, as it demonstrates that the categories of subject and object are not fundamental categories. In this regard concerning the self, Hume made a significant advancement compared to Berkeley.

The most crucial part of the entire "Treatise" is the section titled "On Knowledge and Probability." Hume does not imply by "probability" a kind of knowledge included in the mathematical theory of probabilities, such as the fact that the chance of rolling double sixes with two dice is 1/36. This knowledge is not itself probable in any special sense. It has as much certainty as can be found in knowledge. What Hume addresses is uncertain knowledge, such as that derived from empirical data through conclusions that are not demonstrative. It encompasses all our knowledge concerning both the future and parts of the past and present that have not been observed. In fact, it includes everything except direct observation on one hand, and logic and mathematics on the other. An analysis of such "probable" knowledge led Hume to certain skeptical conclusions that are equally difficult to refute or accept. The result is a challenge to philosophers, to which, in my view, a proper answer has yet to be given.

Hume begins by distinguishing seven kinds of philosophical relations: resemblance, identity, relations of time and place, quantitative or numerical relations, degrees of any quality, contradiction, and causation. He asserts that they can be divided into two types: those that depend solely on ideas, and those that can be altered without any change in ideas. The first type includes: resemblance, contradiction, degrees of quality, and quantitative or numerical relations, while spatial-temporal and causal relations fall into the second type. Only relations of the first type yield certain knowledge; our knowledge of other relations is merely probable. Algebra and arithmetic are the only sciences in which we can construct a long chain of reasoning without compromising certainty. Geometry is not as certain as algebra and arithmetic because we cannot be confident in the correctness of its axioms. It is erroneous to assume, as many philosophers do, that the ideas of mathematics "must be grasped through pure, intellectual contemplation, accessible only to the highest faculties of the soul." The fallacy of this view becomes evident, Hume argues, as soon as we remember that all our ideas are copies of our impressions.

Three relations that do not depend solely on ideas are identity, spatial-temporal relations, and causation. In the first two, the mind does not extend beyond what is immediately presented to the senses. (Spatial-temporal connections, Hume believes, can be perceived and can form parts of impressions.) Causation, on the other hand, allows us to derive one thing or phenomenon from another: "Only one causation engenders such a connection, through which we draw certainty from the existence or action of some object that another existence or action followed or preceded."

The difficulty arises from Hume's assertion that there is no such phenomenon as an impression of a causal relation. We may perceive through simple observation A and B, noting that A is positioned above B or is to the right of B, but not that A is the cause of B. In the past, the relation of causality was more or less likened to the relation of ground and consequence in logic; however, Hume rightly considers this erroneous.

In Cartesian philosophy, as well as in the philosophy of the scholastics, the connection between cause and effect was assumed to be as necessary as logical connections. The first serious challenge to this view originated with Hume, from whom modern philosophy of causality commenced. He, like nearly all philosophers of the modern era, including Bergson, believed that the law asserts that there are judgments of the form: "A is the cause of B," where A and B are classes of phenomena; the fact that such laws do not exist in highly developed sciences is apparently unknown to philosophers. Yet much of what they have said can be rephrased to apply to causal laws that actually exist; therefore, we need not presently dissect this viewpoint.

Hume begins by asserting that the force by which one object produces another is not revealed by the ideas of the two objects; thus, we can learn about cause and effect only through experience, not through reasoning or contemplation. The assertion that "what begins to exist must have a cause for its existence," he claims, is not a statement that possesses intuitive certainty, like the assertions of logic. He expresses it thus: "There is no object that contains within itself the existence of another object—if we consider these objects as such, without transcending the ideas we form of them." From this, Hume argues that only experience should provide knowledge of cause and effect, but that it cannot simply be the experience of two phenomena A and B that are causally connected. This must be experience because the connection here is not logical; and it cannot simply be the experience of singular phenomena A and B, as we cannot uncover anything in A itself that would compel it to produce B. Experience requires, he states, a constant conjunction of phenomena of kind A with phenomena of kind B. He points out that when two objects are constantly conjoined in experience, we actually derive one from the other. (When he says "derive," he means that the perception of one event leads us to expect another; he does not refer to a formal or evident deduction.) "Perhaps, the necessary connection is conditioned by the conclusion," rather than the reverse. In other words, the appearance of A is the cause of the expectation of B, and thus this leads us to the belief that there exists a necessary connection between A and B. The deduction is not established through reason, as that would require us to assume the unity of nature, which is not itself a necessity but is only derived from experience.

Thus, Hume arrives at the view that when we say "A is the cause of B," we mean that A and B are in fact constantly conjoined, rather than that there exists some necessary connection between them. "We have no other notion of cause and effect than that of certain objects which have always been conjoined together… We cannot discover the foundation of this conjunction."

He supports his theory by defining "belief," which he asserts is "a lively idea associated with a relation or associated with a present impression." By association, if A and B have been constantly conjoined in past experience, the impression of A evokes such a lively idea of B that it forms belief in B. This explains why we believe that A and B are connected: the perception of A is linked with the idea of B, and thus we begin to think that A is related to B, even though this belief is, in fact, unfounded. "Between objects there is no connection accessible to our observation, and it is only through the habits that operate on the imagination, and not by any other principle, that we can draw a conclusion about the existence of one object from the existence of another." He reiterates that what appears to us as a necessary connection between objects is, in reality, merely a connection between the ideas of those objects: habit compels the mind, and "this impression, or compulsion, gives me the idea of necessity." The repetition of examples leading us to believe that A is the cause of B reveals nothing new in the objects themselves, but instead leads to an association of ideas; thus, "necessity is something that exists in the mind, not in the objects."

Let us ask ourselves what we ought to think about Hume's doctrine. It consists of two parts: objective and subjective. The objective part asserts that when we suppose A is the cause of B, the fact that has actually taken place, insofar as it pertains to A and B, is that they have often been observed together, meaning B directly or very quickly follows A; however, we have no right to assert that B must follow A or will follow A in the future. We have no grounds for assuming that from the frequent following of B by A any connection, beyond mere sequence, is warranted. In fact, causality can be defined by means of sequence, and it is not an independent concept.

In the subjective part of the doctrine, it is asserted that the often-observed coincidence of A with B gives rise to the impression that A is the cause of ideas about B. Yet, if we are to define "cause" as proposed in the objective part of the doctrine, we must rephrase the aforementioned. After substituting the definition of "cause," the above would read as follows: "It has been often observed that the repeatedly observed connections of the two objects A and B have been accompanied by phenomena in which the idea of B follows the impression of A."

We may agree that this assertion is true, but it hardly possesses the breadth that Hume ascribes to the subjective part of his doctrine. He repeatedly asserts that the frequently repeated coincidences of A and B do not provide any grounds to expect that they will coincide in the future; rather, they merely cause that expectation. In other words, the experience of frequently repeated coincidences often aligns with the habit of association. Yet if we accept the objective part of Hume's doctrine, then from the fact that associations were often formed under such circumstances in the past, there is no basis for assuming they will continue to form or that new associations will be created under similar circumstances. The matter is that when it comes to psychology, Hume allows himself to believe in causality in a sense that he fundamentally condemns. For instance, I see an apple and expect that if I eat it, I will taste a certain flavor. According to Hume, there are no grounds for why I should taste that flavor: the law of habit explains the existence of my expectation but does not justify it. However, the law of habit itself is a causal law. Therefore, if we take Hume seriously, we must say that although in the past the sight of the apple coincided with the expectation of a certain taste, there is no reason why such a coincidence should occur in the future: perhaps the next time I see an apple, I will expect it to taste like roast meat. You may think at this moment that this is incredible, but that is not a basis for expecting that you will think it is incredible five minutes later. If Hume's objective theory is correct, then we have no greater grounds for the possibility of expectations in psychology than in the physical world. Hume’s theory could be parodied as follows: the statement "A is the cause of B" means "the impression of A is the cause of the idea of B." As a definition, it is by no means a fortunate discovery.

Therefore, we must examine Hume's objective theory more closely. This doctrine has two parts: 1) when we say "A is the cause of B," all we are entitled to assert is that in past experience, A and B have often appeared together or in rapid succession, and there has not been a single instance where B did not follow A or accompany it; 2) however many examples of the coincidence of A and B we may observe, this does not provide grounds to expect that they will coincide in the future, even though it is the cause of that expectation, meaning it has often coincided with such an expectation. These two parts of the doctrine can be summarized as follows: 1) there is no indefinable relation in causality, except for coincidence or sequence; 2) induction through enumeration is not an effective form of proof. Empiricists generally accepted the first of these theses and rejected the second. When I say they rejected the second, I mean that they believed that with a sufficiently large number of examples of coincidences, the probability of finding a coincidence in the next example would be greater than half, or if they did not adhere precisely to this, they proposed some theory with the same consequences.

At this moment, I have no desire to discuss induction, which is a large and complex topic; I shall limit myself to the observation that if we accept the first half of Hume's doctrine, then the denial of induction renders any expectation about the future unreasonable, even the expectation that we will continue to experience expectation. I do not merely mean that our expectations may be erroneous. This must be admitted in any case. I believe that even taking our most certain expectations (such as the expectation that the sun will rise tomorrow), there is not a shred of evidence to suggest that the probability of their confirmation is greater than the probability that they will not be confirmed. With this caveat, I return to the meaning of "cause."

Those who disagree with Hume assert that "cause" is a specific relation that entails a constant consequence, but the consequence does not entail the cause. Let us return to the Cartesian clocks: two perfectly accurate timepieces may strike the hour one after the other, each not being the cause of the other striking. Generally, those who have held this view argue that we can sometimes perceive causal connections, although in most cases we are compelled to conclude them more or less randomly from constant coincidence. Let us examine what arguments there are for and against Hume on this matter.

Hume summarizes his arguments in the following manner: "I fully recognize that among all the paradoxes I have expressed and will express in my treatise, this one is the most striking; and only by resorting to solid evidence and reasoning can I hope for it to be accepted and to triumph over the deep-seated prejudices of humankind. Before reconciling ourselves to this doctrine, how many times must we repeat to ourselves that the mere perception of two objects or actions, irrespective of their relations to one another, can never bestow upon us any power or connection between them; that this idea arises from the repetition of their conjunction, which does not unveil or produce anything within the objects themselves but only influences the mind through the accustomed transition it engenders? Thus, this habitual transition is identical to what we term power and necessity, which, consequently, are qualities of perceptions rather than of objects—qualities that are internally felt by our souls rather than externally observed in bodies."

Hume is often criticized for his overly atomistic view of perception, yet he concedes that some relations can indeed be perceived. "We should not consider any of our observations regarding identity or the relations of time and space as reasoning," he asserts, "for in none of these observations does our mind transcend the limits of what is directly perceived by the senses." Causation, he argues, is distinctive in that it draws us beyond the impressions of our senses and provides us with knowledge of unperceived existences. This claim may seem, at first glance, to lack a solid foundation. We believe in the existence of many temporal and spatial relations that we cannot perceive; we assume that time extends into the past and future, and that space stretches far beyond our immediate surroundings. Hume's actual argument lies in the observation that while we sometimes perceive relations of time and space, we never perceive causal connections that would have to be deduced from the relations we can perceive. The debate thus reduces to a single empirical fact: do we sometimes perceive what can be called a causal connection or not? Hume says no; his opponents say yes. It is not easy to navigate the evidence presented by each side.

I believe that perhaps the strongest argument in favor of Hume can be derived from the nature of causal laws in physics. It becomes evident that simple formulations such as "A is the cause of B" are never accepted in science except as rough assumptions at its early stages. The causal laws that replace such simplistic formulations in advanced sciences are so complex that no one can propose they are given in perception; they are clearly the result of meticulously crafted deductions from the observable processes of nature. I set aside discussions of contemporary quantum theory, which reinforces this conclusion. As far as the physical sciences are concerned, Hume is entirely correct: a judgment such as "A is the cause of B" can never be accepted, and our tendency to accept it can be explained by the laws of habit and association. These laws, in their precise form, will ultimately be thoroughly developed statements concerning the nervous system: initially its physiology, then its chemistry, and finally its physics.

However, Hume's adversary, even if he broadly accepts what has been said about the physical sciences, may not yet consider himself decisively defeated. He may argue that in psychology we have instances where causal relations can be perceived. Generally, the concept of cause likely stems from a volitional act, and it can be said that we are capable of perceiving the relation between the volitional act and the subsequent action, which constitutes something more than mere unchanging action. The same could be said for the connection between sudden pain and a scream. However, such views have proven exceedingly challenging for psychology. Between the desire to move one’s hand and the ensuing motion lies a long chain of causal intermediate phenomena consisting of processes within the nerves and muscles. We perceive only the terminal members of this process—the volitional act and the movement—and if we think we see a direct causal connection between them, we are mistaken. This argument is not exhaustive regarding this broad question, but it demonstrates the recklessness of assuming we perceive causal relations when we believe we are acting. Thus, the weight of the debate on causality tips in favor of Hume's view that there is nothing in causation but a constant sequence. Yet the proof is not as conclusive as Hume presumed.

Hume does not content himself with reducing the proof of causal connection to the experience of frequently occurring conjunctions; he continues to argue that such experience does not justify the expectation of similar conjunctions in the future. For instance, when (to reiterate the previous example) I see an apple, my past experience leads me to expect that it will taste like an apple rather than roast beef, but there is no rational justification for such an expectation. Were there a justification, it would stem from the principle that "those cases we have not yet encountered in experience should resemble those we have already become acquainted with through experience." This principle is not a logical necessity, as we can at least suppose changes in the order of nature. Therefore, it would be a principle of probability. However, all probable arguments presuppose this principle; thus, it cannot be proven by any probable argument nor can its likelihood be demonstrated by any such arguments. "The assumption that the future resembles the past is not based on any arguments but arises solely from habit." Hume's conclusion is steeped in skepticism.

"Every probable reasoning is nothing but a kind of feeling. Not only in poetry and music, but also in philosophy, we must follow our taste and feeling. When I am convinced of some principle, it merely means that a certain idea exerts a particularly strong influence upon me; when I favor one chain of arguments over another, I am merely deciding based on the feeling of which one has a more potent effect on me. Between objects, there is no necessary connection accessible to our observation, and it is only through the imagination's habitual influence, and not any other principle, that we can infer the existence of one object from the existence of another."

It can be assumed that the ultimate result of Hume's investigation into what constitutes knowledge is not as he would have wished. The subtitle of his book reads: "An Attempt to Introduce the Experimental Method of Reasoning into Moral Subjects." Clearly, he embarked upon this endeavor believing that the scientific method would lead to truth, complete truth, and would yield nothing but truth; however, he concluded with the conviction that to believe is unreasonable, for we know nothing. Following his exposition of the arguments in favor of skepticism, he continues his work not to refute those arguments but rather to appeal to natural credulity.

Nature, by virtue of absolute and immutable necessity, has dictated that we express judgments, just as it has prescribed that we breathe and perceive. We cannot refrain from forming stronger and more comprehensive representations of certain objects due to their habitual association with existing impressions any more than we can refrain from thinking while awake or seeing the bodies around us when we turn our gaze toward them in bright sunlight. Anyone who has endeavored to refute the cunning of this comprehensive skepticism has, in truth, engaged in a dispute with a non-existent opponent, attempting to establish, through arguments, a capacity that nature has endowed our minds with from the very beginning, rendering it indispensable to us. Thus, in meticulously articulating the arguments of this sect of fantasists, I strive merely to persuade the reader of the veracity of my hypothesis: that all our conclusions regarding causes and effects are founded solely on habit and that faith constitutes an act of the sensing rather than the thinking aspect of our nature.

The skeptic, he continues, persists in reasoning and believing, even while claiming that he cannot defend his mind through reason; for the same reasons, he must also acknowledge the principle of the existence of bodies, even though he cannot lay claim to proof of its truth through any arguments. We might indeed ask, "What reasons compel us to believe in the existence of bodies?" However, inquiring, "Do bodies exist or not?" proves futile. This point must feature in all our reasoning as an indisputable fact.

The passage above serves as the introduction to the section "On Skepticism Regarding the Senses." Following a lengthy discourse, this section concludes with the following assertion:

"This skeptical doubt concerning both reason and the senses is a malady that can never be radically cured but must return to us moment by moment, regardless of our efforts to expel it, even if at times we seem entirely liberated from it. Only carelessness and inattentiveness can provide us any assistance in this regard. Thus, I fully rely on these qualities and deem it certain that, regardless of the reader's current opinion, an hour later he will be convinced of the existence of both the external and internal worlds."

According to Hume, no grounds exist for studying philosophy other than the opportunity it provides certain natures to pass their time pleasantly. "We must maintain our skepticism in all matters of life. If we believe that fire warms and water refreshes, it is because holding any other opinion would cause us too much suffering; moreover, we must become philosophers solely on the basis of skeptical principles, and only when we feel inclined to devote ourselves to such pursuits." Were he to dismiss theory, he might declare, "I feel I would lose a measure of the pleasure I presently experience. Thus is the origin of my philosophy."

Hume's philosophy, whether true or false, signifies the collapse of eighteenth-century rationalism. He, like Locke, commences with the intention to be sensualist and empirical, accepting nothing on faith, yet seeking all indications that can be gleaned from experience and observation. However, being more astute than Locke, more precise in analysis, and less inclined to acquiesce to contradictory assertions that sometimes offer solace, he arrived at the unfortunate conclusion that nothing can be known through experience and observation. There exists no phenomenon known as rational faith: "If we believe that fire warms or water refreshes, it is because holding any other opinion would cause us too much suffering." We cannot cease to believe, but no belief can be grounded in reason. No course of action can be more rational than another, as all are equally based on irrational convictions. Yet, it seems, Hume did not arrive at this last conclusion. Even in his most skeptical chapters, where he summarizes the conclusions of Book I, he states, "Generally speaking, religious delusions are dangerous, whereas philosophical ones are merely ludicrous." He had no right to make this assertion. "Dangerous" is a causal term, and a skeptic regarding causality cannot know whether anything is "dangerous."

In fact, in the latter sections of the "Treatise," Hume entirely forgets his foundational doubts and writes more in the manner of any other enlightened moralist of his time; he applies to his doubts the remedy he recommends, namely "carelessness and inattentiveness." In this sense, his skepticism lacks sincerity, as he does not practice it. This, however, leads to the absurd consequence that negates any attempt to prove that one course of action is better than another.

It was inevitable that such a self-contradiction of rationality would provoke a great outbreak of irrational faith. The quarrel between Hume and Rousseau is emblematic: Rousseau was reckless yet influential, while Hume was sensible yet devoid of followers. Subsequent British empiricists rejected his skepticism without disproving skepticism as a whole; Rousseau and his followers concurred with Hume that no belief rests on reason but maintained that feelings surpass reason, thus arriving at beliefs that were entirely distinct from those Hume practiced. German philosophers, from Kant to Hegel, did not adopt Hume's arguments. I state this deliberately, counter to the opinion shared by many philosophers, including Kant, that his "Critique of Pure Reason" was a response to Hume. In truth, these philosophers, at least Kant and Hegel, represent a pre-Humean type of rationalism and can be refuted by Hume's arguments. The philosophers who cannot be challenged in such a manner are those who do not claim rationality, such as Rousseau, Schopenhauer, and Nietzsche. The rise of illogic throughout the nineteenth century and into the twentieth century naturally follows from Hume's dismantling of empiricism.

Thus, it becomes crucial to ascertain whether within the confines of philosophy itself exists any response to Hume that would be entirely or fundamentally empirical. If not, then no intellectual distinction exists between the rational man and the madman. One could condemn a mentally ill individual who believes himself to be a poached egg solely on the grounds that he is in the minority, or rather—since we should not presume democracy—on the grounds that the government does not concur with him. This is a dreadful perspective, and one must hope there is a way to evade it.

Hume's skepticism entirely rests upon his denial of the principle of induction. The principle of induction, when applied to causality, asserts that if B is frequently found accompanying A or following it, and no example exists wherein B did not accompany or follow A, then it is probable that the next time A is observed, B will accompany it or follow it. If this principle is valid, then a sufficient number of examples should render the probability nearly certain. However, if this principle, or any other from which it may be derived, is true, then the causal conclusions that Hume rejected are effective not as conclusions that provide certainty but as conclusions that offer sufficient probability for practical purposes. If this principle is not true, then any attempt to derive general scientific laws from particular observations is erroneous, and Hume's skepticism becomes inevitable for the empiricist. Certainly, outside of mutual justification, the principle itself cannot be derived from observable uniformities, as each such conclusion requires justification. Therefore, it must be an independent principle, not founded on experience, or a deduction from it. Up to this point, Hume demonstrated that pure empiricism does not provide a sufficient foundation for science. Yet, if this one principle is permitted, everything else may align with the theory that all our knowledge is based on experience. It must be acknowledged that this represents a significant deviation from pure empiricism and that those who do not identify as empiricists may question why, if one deviation is permitted, others are prohibited. However, these inquiries do not arise directly from Hume's arguments. What these arguments demonstrate—and I believe this proof is undeniable—is that induction is an independent logical principle that cannot be derived from experience or from other logical principles, and that without this principle, science is impossible.