Philosophy of the Modern Era

The Problem of the Method of Knowledge: Empiricism and Rationalism

The founders of modern philosophy are rightly considered to be the English philosopher Francis Bacon and the French philosopher René Descartes. From them begins the philosophy of the Modern Era, as they establish the principles of a new science, the very science we know today. Their philosophies, especially Descartes', completed the shift in worldview initiated during the Renaissance, placing the problem of the method of knowledge at the center of philosophical inquiry and giving rise to two philosophical movements of the Modern Era—empiricism and rationalism.

Francis Bacon (1561-1626) was among the first to recognize the necessity of a new science and to articulate its objectives. In the opening of his principal work, "Novum Organum" (New Organon), he asserts that science is not "idle learning," not knowledge for knowledge's sake, but rather a means for transforming nature and reconstructing human life. "Knowledge and human power coincide, for ignorance of causes impedes action," he declares. "Nature is conquered only by obeying her, and what appears to be a cause in contemplation proves to be a rule in action." The goal of science cannot be anything other than "endowing human life with new discoveries and goods."

However, Bacon astutely recognizes that the underdevelopment of "natural philosophy" (as he calls it) largely stems from the intermingling of philosophy with religion, wherein philosophy has been subordinated to it. Thus, in contrast to the principle proclaimed by Thomas Aquinas and upheld by the Church—that philosophy is the handmaiden of theology—he introduces the principle of the duality of truth. Bacon likens knowledge to water: it either falls from the sky or wells up from the earth. The knowledge that comes from the heavens, from God, constitutes theology, while that which arises from nature and is rooted in sensation comprises natural philosophy. The sciences of nature must be shielded from the influence and intrusion of religion. Only along this path can a new science be formed.

Yet this is not sufficient. For a new science to become possible, human reason, in Bacon's view, must be purged of the idols that distort knowledge. He identifies four types of idols that beset human understanding: the idols of the tribe, the idols of the cave, the idols of the marketplace, and the idols of the theater.

Idols of the tribe are rooted in human nature itself, in the tendency of humans to consider their own senses as the measure of all things. However, the human mind is prone to impose more order on nature than it possesses; it tends to uphold what it has accepted; "it is drenched in will and passions"; it is most influenced by that which most affects it; it relies on senses that are imperfect and deceptive. Thus, it anthropomorphizes nature, distorting it.

Idols of the cave are similar in nature to the idols of the tribe but are connected to the individual peculiarities of the mind, upbringing, passions, and habits. People tend to prefer what they have invested the most effort into; some are more inclined to venerate antiquity, others to novelty; they favor what is most closely tied to their experience.

However, the greatest obstacles to knowledge are the idols of the marketplace. These idols arise from the fact that the words of everyday language, sourced in the thoughts of the crowd, are transferred into science, thereby distorting the true nature of phenomena and hindering the inquisitive mind from penetrating the nature of things.

The aforementioned idols are either innate or secretly infiltrate the mind through upbringing and social interactions. The fourth type of idols—the idols of the theater—possess a different nature. They are consciously embraced and propagated through invalid philosophical concepts. The roots of erroneous thoughts in false philosophy are threefold: sophistry, empiricism, and superstition.

The mind, if it wishes to comprehend nature, must be cleansed of these idols. Only in this way, Bacon argues, can a genuine science of nature be established—one that was either entirely absent or given very little attention in the prior history of humanity.

The aim of the new science is to grasp the forms of objects and phenomena, to uncover the formal cause. Here, Bacon understands "form" not as Aristotle’s formative principle but as a law, the discovery and explanation of which provides a foundation for both knowledge and action. For him, form is akin to the concept of essence that defines the type of phenomena.

However, the creation of new science necessitates the development of a new method, a new logic of inquiry. The role of method is immensely significant: "…a lame man walking along the road outstrips one running without a road," Bacon asserts regarding the importance of method. Thus, method is the path to the discovery of truth. Scholasticism employed the deductive method established by Aristotle. Yet the issue with the deductive method is that it does not yield new knowledge and is therefore unsuitable for understanding nature.

According to Bacon, the method of the new science can only be the inductive method—the approach of ascending from the particular to the general. Science must begin with experience, with experimentation—this is the central tenet of Bacon's method. However, the inductive method can provide only probable knowledge, except in cases of complete induction, which is not significant for science. Therefore, the primary task facing Bacon is to demonstrate how induction can yield reliable knowledge.

The main flaw of the inductive method, which was also employed by the old philosophy, lay in the fact that experience was haphazard, unstructured, and experimentation was altogether absent. Based on this random, limited experience, philosophers would leap to general axioms, formulating broad conclusions that were speculative in nature and incapable of revealing the true essence of phenomena.

To rectify the inductive method and make it suitable for attaining reliable knowledge, experience must be rendered systematic. From experience and observations, one must progress to higher axioms through intermediary axioms, which Bacon emphasizes as crucial. The movement of knowledge from experience to axioms he envisions in the form of tables of knowledge. To ascertain the form of a phenomenon, it is necessary to present to the mind all known examples in which the nature of that phenomenon manifests. This table Bacon calls the table of essence or presence.

Subsequently, one must create a table of deviations or absence, enumerating instances where the given nature or form is not evident—a task not previously undertaken in philosophy. Since there may be numerous such examples, the second table must correlate with the first, selecting the most closely related instances.

After this, it is necessary to present to the mind examples in which the given nature or form is present to a greater or lesser degree. This will constitute the table of degrees or comparisons. Once these three tables are mentally represented, the work of the mind begins, which consists in analysis, in deconstructing and dividing nature, in discarding and excluding that which randomly appears in any example. Only after this can we proceed to interpret nature in a positive sense, providing it with an explanation. This method, Bacon argues, is capable of yielding reliable knowledge, and only through such a method can a new science be created.

Bacon is considered the progenitor of empiricism in the philosophy of the Modern Era, although he himself criticized the extremes of both empiricism and rationalism. He compared the empiricist to an ant that, unable to see the forest for the trees, neglects the broader picture, while the rationalist is likened to a spider weaving its web from itself. The true scholar, however, resembles a bee, gathering nectar from flowers and transforming it into honey. By advocating that genuine knowledge must be rooted in experience, he undoubtedly contributed to the formation of an empirical approach to the process of knowledge in England, which was further developed by Thomas Hobbes (1588-1679), John Locke (1632-1704), George Berkeley (1685-1753), and David Hume (1711-1776). If Locke can be viewed as a moderate empiricist, expressing a positive stance toward experimental sciences and a skeptical approach to speculative systems that cannot be empirically verified or are logically obscure, then Hobbes, Berkeley, and Hume are consistent, radical empiricists who assert that the source of our knowledge of nature can only be sensations. Only sciences such as mathematics and logic are constructed on the basis of freely established rational rules. From his radical empirical stance, Hume arrives at agnosticism—the denial of the possibility of obtaining reliable knowledge.

Another vision of the new science can be found in the works of the French philosopher René Descartes (1596-1650). Like Bacon, Descartes perceives the futility and emptiness of the preceding scholastic learning. He shares Bacon's conviction that a reliable method of knowledge is essential for the establishment of a new science. According to Descartes, two principles must form the foundation of this new method: the principle of doubt and the principle of rational self-evidence. In contrast to Bacon, Descartes develops a deductive method of knowledge, initiating rationalism and a new cultural paradigm based on rational foundations. It is crucial to note that Descartes' notion of "doubt" carries a deeper significance than mere skepticism and the quest for proof of the validity or invalidity of already established scientific positions. Descartes' "doubt" implies a search for and rejection of that which can logically be doubted.

Descartes, like all philosophy of the New Age up to Hegel, holds that the subject of knowledge is the individual endowed with sensory and rational capacities for understanding. In this context, philosophy faces the task of clarifying which types of knowledge can yield reliable truths upon which science must rely, so that its conclusions provide genuine knowledge and can guide practical action. For both Bacon and Descartes, science is essential for organizing and restructuring our lives; thus, the credibility of knowledge primarily bears practical significance.

Through logical reasoning, Descartes concludes that empirical knowledge—knowledge acquired through experience—cannot serve as a robust foundation for science. These arguments, however, were already known in antiquity. Can one doubt the information provided by the senses? Descartes answers affirmatively. From a distance, a rectangular tube appears round; railway tracks converge in the distance; we may be subject to hallucinations and similar phenomena. In practice, we can adjust our sensations and perceptions to establish truth, but logically, it is undeniable that the senses can deceive us, and we can only verify their claims through other sensory experiences. If our senses have deceived us once, how can we be certain that new sensory perceptions are not erroneous? From this, Descartes concludes that it is impossible to base science on sensory experience, and thus on the inductive method.

Descartes is convinced that the foundation of the new method and the new science can only be reason. Certainly, reason can also err, but this occurs because we do not critically examine the content of our thoughts and lack systematic thinking. Only through thought can we find the criterion of truth; only within consciousness, particularly in its element of self-awareness, can we discover a basis in which we cannot fundamentally doubt. This foundation, devoid of doubt, is our conviction in our very thinking, and thus in our existence. "... Noticing that in truth the proposition 'I think, therefore I am' is convinced by the only understandable fact that to think one must exist, I concluded that it is possible to take as a general rule this: everything that is imagined by us is entirely understandable and true." In general, the judgment "I think, therefore I am" was articulated by Augustine. However, in Augustine's context, it serves as one of his arguments in a debate with skeptics, demonstrating to them that its truth is beyond doubt and that agnosticism is thus untenable. In Descartes' philosophy, it acquires the status of a "credo," a foundational principle for all of Descartes' philosophy. From this, Descartes formulates four rules of his deductive method, the first of which is decisive: "... Never accept as true anything that I do not recognize as such with absolute clarity; that is, I must meticulously avoid haste and prejudice, and only include in my judgments that which is presented to my mind so clearly and distinctly that it cannot give rise to doubt."

The three other rules—1) to divide each difficulty into as many parts as necessary for better resolution, 2) to proceed in my reasoning from the simple to the complex, and 3) to compile comprehensive lists—are of less fundamental significance and, in fact, align with Bacon's methodological rules.

Why does Descartes start from the principle of self-evidence? This stems from the important fact that Descartes himself is a mathematician, and at this time, mathematics and the mechanics derived from it dominate the scientific landscape. As is well known, mathematics is founded on axioms, upon which the entire structure of mathematics is built. Alter the axioms, and the entire edifice of science may either collapse or appear entirely different (as seen in the geometries of Euclid and Lobachevsky).

Yet, another crucial question for the rationalist method arises, to which Descartes must respond: From where does the clarity of the mind regarding primary axioms, starting points, and further irreducible propositions originate? According to Descartes, these propositions are intuitive. Here, Descartes understands intuition not as something mystical that transcends reason, but rather as "the understanding of a clear and attentive mind, so simple and distinct that there remains absolutely no doubt regarding what we understand, or, similarly, an undoubted understanding produced solely by the light of reason, which is more straightforward and thus more reliable than deduction itself." Furthermore, Descartes introduces innate ideas into his philosophy. He posits that the thinking substance inherently possesses certain general concepts, ideas that are innate rather than acquired through experience. Such ideas include the concept of God, as well as ideas of numbers and shapes, among others. These truths embody the natural light of reason and also serve as starting points for deduction.

Thus, in contrast to Bacon, Descartes consistently upholds the principle of rationalism, seeing the criterion of truth in reason and only in reason. For science to be true, it must begin with self-evident ideas accessible to reason, systematically and sequentially constructing its entire structure through rational intuition and deduction.

Descartes' rationalism found successors in the Dutch philosopher B. Spinoza (1632-1677) and the German philosopher G.-W. Leibniz (1646-1716). Like Descartes, they believed that only reason can be the source of truth, and that clarity and self-evidence must serve as the criteria of truth, in opposition to empiricists who maintain that experience is the source of truth, and observation and empirical scrutiny are its criteria.