In the history of philosophy, and especially in the field of epistemology, there has never been a fiercer debate than the one between rationalists and empiricists. Rationalists argued that the ultimate source of our knowledge is human reason. On the other hand, empirically oriented thinkers thought that it is through our experience that we gain knowledge of the world, and it is the experience that determines and limits of our knowledge. But what did their arguments and objections against one another really consist of?
The Basics of Rationalism
First, let’s examine the philosophy of rationalism, and then move onto empiricism. We can define rationalism as a philosophical teaching about the relationship between man and the world, based on the conviction that reason (ratio) or intellect (intellectus) is the basic source of knowledge, the criterion of the truth of knowledge, and the means we use to gain knowledge about the world. Reason is also that which determines the possibilities and limits of human knowledge and the most significant feature of man as a moral and practical being. Rationalism has a rich tradition in the history of European philosophical schools. That’s why it’s important to examine its history throughout the centuries.
1. Rationalism in the Ancient Period
In the ancient period, rationalism was represented in the philosophical teachings of the Pythagorean, Elean, and atomistic schools. Their ontologies are built on the rationalist methodology represented in mathematical, logical, or theoretical speculative thought.
However, the full flowering of rationalism in antiquity coincides with the teachings of the leading philosophers of this era: Socrates, Plato, and Aristotle. Socrates’ enlightened rationalism, created at the height of the struggle with the sophists, manifests itself in the well-known dialogic skill of arriving at clear definitions of terms. This goal is inspired by Socrates’ conviction that virtues are obtainable only through knowledge. From there, he emphasizes the well-known imperative as the guiding principle of all his thinking and action: Know thyself.
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However, Plato can be considered the true founder of ancient rationalism. With Plato, for the first time in ancient philosophy, we encounter a fully developed system of rationalism as a study of knowledge, its sources, objects, criteria, possibilities, and scope. In his teaching about ideas, Plato established a rationalist-founded objective idealism, and in its scope, he created his metaphysics, epistemology, ethics, and so on.
Aristotle highly valued experience and its methods. However, he is nevertheless one of the most significant rationalists. As proof of that, we have his foundational works dedicated to logic. Thus, we can say that ancient rationalism reaches its peak in Aristotle’s Metaphysics.
2. Rationalism in the Modern Period (and Beyond)
European rationalism reaches its true flowering in the period known as modern philosophy. Three of the foremost luminaries of modern philosophical thought—Descartes, Spinoza, and Leibniz—are rationalists in the full sense of the word. Therefore, rationalism as a philosophical direction is mostly associated with the names of these philosophers.
Descartes is considered the founder of the rationalist theory of knowledge. Descartes established the position Cogito ergo sum (I think, therefore I am). He considered reason to be endowed with innate ideas and principles and as such, established it as the most important instrument of knowledge and the guarantor of truth. He advocated for the critical examination of reason and formulated its rules. Descartes also sought to raise the basic method of knowledge to the level of a universal scientific method according to the model of mathematics (mathesis universalis).
The second most significant rationalist is Spinoza. He’s important in the history of rationalism because of the systematic and consistent implementation of the deductive method following the pattern of geometry in his Ethics. The main point of his system is the demonstration of the inseparable connection of reason as the most significant cognitive power with the highest and most sublime goals of moral action.
Leibniz is considered the first real representative of the systematic application of rationalism in the sphere of knowledge. He discusses almost all the questions of the theory of knowledge that were discussed by his famous predecessors. Leibniz gave systematic rationalistic grounded answers to all questions about the origin, object, possibilities, limits, logical basis, and value of human knowledge.
The speculative philosophy of the two eminent representatives of German classical idealist philosophy—Hegel and Schelling—can be considered a special form of rationalism. Their philosophical systems are evidence of an encyclopedic approach to all spheres of existence.
Following the historical timeline further, one can also talk about the rationalism of Karl Marx and his numerous followers—Marxists, as a separate type of rationalism: dialectical rationality.
Today there are also contemporary variants of rationalism, and among them, a special place belongs to the critical rationalism of Karl Popper.
3. The Philosophical Principles of Rationalism
It is important to analyze the postulates and arguments that rationalist thinkers provide in favor of their view.
1. Reason is the only source of all true knowledge
According to the rationalists, reason represents the only source or our only power for acquiring real knowledge: general and necessary truths. Although with certain differences, this thesis is accepted by all followers of rationalism.
For example, for Plato, the source of knowledge is in the “remembering of the soul” of its original residence in the “kingdom of ideas.” The power of reason, according to Plato, is the power of the soul to recall ideas and recognize them as such. Ideas are nothing but general and necessary truths. Thus, with the theory of the remembering of the soul (anamnesis), Plato laid the foundations of the Western rationalist theory of the origin of knowledge: the theory of innate ideas and principles of reason.
According to Descartes, reason is a natural light (lumen naturale) made possible by innate ideas (idee inatae). Thus, both Descartes and Plato advocate the view of innate ideas and principles in man. However, not all ideas are innate, says Descartes, but only a special kind of ideas, such as the idea of God, the ideas that express the general mathematical attitudes of arithmetic and geometry, and the laws and principles of logic. These ideas enable us to acquire knowledge of general and necessary truths. All attitudes derived from these ideas, which are general and necessary are themselves necessarily true because their truth is guaranteed by God himself.
For Leibniz, also, only reason can be the source of this knowledge, which is necessarily true.
2. The basic means of knowledge are intellectual intuition and abstract-logical thought operations
The object of knowledge, according to the rationalists, can only be grasped through the powers of immediate intellectual perception and through intellectual thought operations.
3. The truth of our knowledge is determined by the accordance of our thinking with logical rules and laws, or with general principles established by science
For rationalists, truth can only be determined through the correspondence of expressed views with the laws and principles of reason itself because that is where the rules and regularities of logic come from.
For Descartes, the criterion of the truth of our statements is the clarity and distinctness as a feature of a certain type of statement. Only those statements that impose themselves as self-evident truths, so that we do not allow the slightest possibility of doubting them, are acceptable to science and philosophy.
The Basics of Empiricism
Empiricism is a philosophical teaching based on the belief that all human practical and theoretical activity is based on experience. As opposed to rationalism, empiricism claims that the source of our knowledge and the criterion of truth is not reason but experience. Experience is the means we use to gain knowledge, and it is also what determines truth in the world.
Instead of rationalism, which claims that reason is endowed with an apparatus that enables us to acquire knowledge as well as innate ideas, empiricism claims that there is nothing in reason that has not previously passed through the senses. So, according to the empiricists, the senses are the first stage of acquiring knowledge, and all knowledge must pass through the senses.
1. Empiricism in the Ancient Period
Both empiricism and rationalism have their own rich history in the Western philosophical tradition. We find the empiricist approach to solving philosophical problems even among ancient thinkers. These include the sophists Protagoras and Antiphon, as well as the Cyrene Aristippus. Empiricist views were also advocated by the ancient skeptics, especially Sextus Empiricus.
Two fundamental philosophical positions are attributed to the sophist Protagoras: 1.) Man is the measure of all things, and 2.) As something appears to someone, that is exactly what it is. With these two points, Protagoras stands out as the first thinker in the Western tradition who gives complete legitimacy to the subjectivity of human knowledge. In fact, such subjectivity comes from the sphere of experience, which is necessary and inevitable in the creation of all our knowledge.
According to Antiphon, things can be truly known only through the senses, because our opinions (reason) are much more distant from nature.
Ancient empiricism is also characterized by the skepticism of academics, primarily that of Carneades and Sextus Empiricus. What they were trying to do was figure out ways that would go against the rationalist foundation of certain mathematical and metaphysical statements.
2. Empiricism in the Modern Period (and Beyond)
Empiricism experienced its true flourishing in the philosophy of the modern period. Its homeland is Britain, although it quickly spread to the European continent, to France and Germany specifically. The ground for the establishment of empiricism was laid by English thinkers from the scholastic period: Duns Scott, William Ockham, Roger Bacon, and others.
However, Francis Bacon can rightfully be considered the true founder of British modern-day empiricism. He is a significant empiricist because he presents the inductive method as a method of inference, as the true method of acquiring knowledge about nature and establishing truth. The method of induction would later be adopted by all empiricist philosophers. In addition to Bacon, great credit for the establishment of British empiricism also goes to Thomas Hobbes.
However, empiricism as one of the leading directions in the theory of knowledge is associated with the names of the famous trio of British philosophers: John Locke, George Berkeley, and David Hume. The three thinkers gave empiricism the true meaning and made it the leading school of thought of the period.
In the early nineteenth century, an important British empiricist was John Stuart Mill. In France, empiricism is represented by Helvetius and Kondiak, and in Germany, somewhat later, by Feuerbach and the Marxist Dietzgen.
Beginning in the second half of the nineteenth century and throughout the twentieth century, empiricism is prominent in the teachings of neopositivism, pragmatism, and some variants of analytic philosophy.
3. The Philosophical Principles of Empiricism
What is the philosophy of empiricism? What are the main arguments for supporting the claim that experience is the ultimate source of our knowledge? What follows is a brief analysis of some of the most basic empiricist principles.
1. All our knowledge begins with the experiences that are acquired through the activity of the senses
Locke elaborates on this view best. It actually contains his critique of the teaching of innate ideas and principles. Only ideas can be true objects of our opinion for Locke. Our spirit operates with ideas and only with ideas when acquiring any knowledge. There are only two ways we can acquire ideas: through the experiences that our senses give us (sensation) or through the experience that results from the activities of our spirit on these ideas (reflection). So all our knowledge originates either from external experience (sensation) or from internal experience (reflection). But it is by no means possible, Locke proves, for us to have in our minds any innate idea, principle, or knowledge, which has not been produced in some of these two ways. That is why he says of man that he is born as a tabula rasa—a clean unwritten sheet of paper.
David Hume also elaborates on this view. There is no doubt, says Hume, that the real initiator of knowledge can only be experiential contents—the impressions that are acquired by sensory activity. From impressions as a starting point, one comes to representations, and from them to more complex cognitive content. Impressions, says Hume, are direct causes of representations, and not the other way around.
2. Basic means of knowledge are sensory factors: sensations and perceptions
All the “material” of knowledge, according to empiricists, is created through these two factors: sensation and perception. Thinking factors such as judgment and inference also play a role. But, empiricists say, they arise only on the basis of perception. In this way, the role of reason (intellect) begins from the experiential material acquired through sensations and perceptions. The creation of complex ideas, they say, is possible thanks to the fundamental and primary role of sensations and perceptions.
3. The truth of our knowledge is determined by our correspondence with things in everyday experience
The validity of our knowledge, empiricists say, can only be determined by seeing whether our knowledge corresponds to the actual state of the world.
Criticisms of Rationalism and Empiricism
It’s almost inevitable not to think critically and wonder who is in the right and who is in the wrong, rationalists or empiricists. As most things in philosophy go, it turns out things are not so simple, and a definite answer isn’t readily available. However, we can point out some of the weak points and limitations of each of these teachings. In this final part of the article, we’ll take a brief look at some of the limitations of rationalism, as well as of empiricism.
When it comes to rationalism, one could argue that there is no adequate justification for the rationalistic teaching of the existence of innate ideas and principles. Starting from Plato’s world of ideas up to Descartes’ and Leibniz’s theories about the ideas and principles inherent in reason or the soul, rationalists base their teaching on the origin of knowledge on a kind of absolutization of the intellect. However, until today, there are no serious indications that a valid scientific basis can be found for such a thesis.
Empiricism, on the other hand, limits knowledge to what is available through sensory experience. From the position of empiricism, it is very difficult to understand the operations of thought, which is an enormously complex process. Without thought, synthesis, abstraction, generalization, specification, deduction, and induction, it is very difficult to explain how knowledge via the abstract concepts of mathematics, the basic principles of natural sciences, as well as the categories of social and philosophical disciplines, is possible. However, it is very plausible that we, in fact, possess this knowledge. It seems as if experience alone is not enough to grasp this kind of knowledge, especially sensory-perceptive experience. Empiricism, however, is unable to accept sources of knowledge that are independent of experience.
An alternative to the teachings of rationalism and empiricism is Immanuel Kant’s theory of knowledge. His theory is an attempt to overcome the weak points and limitations of both sides; he merges their strengths into one coherent whole. Kant says that knowledge begins with experience (sensibility), then through reason (categories), it ends in the mind (principles). Our knowledge, says Kant, comes from two basic sources of the spirit: the reception of representations (perceptions) and the ability to know an object with the help of these representations (thinking and understanding). Through the first source, the object is given to us, and through the second, it is imagined, says Kant. Accordingly, perceiving (sensibility) and understanding (reasoning) are the two essential powers of human cognition. Thus, Kant concludes that knowledge is impossible without both faculties.