Descartes and Hume: A Comparison of Philosophical Ideas
Descartes: The Method of Doubt
DESCARTES: The aim is to establish certain knowledge against strong doubt. He insists on science, mathematics, and science in particular. * The search for unity: The human way of knowing is unique. Descartes escapes skepticism, deductively constructing a system of indubitable truths. * The problem of ideas: What the spirit or consciousness perceives directly can be: a representation of things in the external world, a memory, or a feeling. Ideas differ in 3 types: “adventitious” or representative of things in the world, “fictitious” invented by the imagination, and “innate” ideas that do not depend on the senses. The ultimate term of experience is the idea of God, which guarantees human knowledge and the correspondence between representations and the world. Under another double referential, ideas are: “clear,” easy to understand, and “dark,” where the mind does not perceive with clarity. Different ideas are often confused. The criterion of truth is that they are real when reason captures ideas perceived clearly and distinctly. * The method of reason: There are only two ways of knowledge: “intuition,” which is clear evidence, and “deduction,” which obtains truths from others. The procedure is from absolute truths to the rest. The deductive method follows 4 rules: “intellectual evidence,” ideas that are clear and distinct; analysis, breaking down into simple elements; synthesis, linking simple elements to reconstruct the complex; and revision, to avoid errors. Observing these 4 rules, reason discovers undoubted truths. * Cartesian metaphysics: For Descartes, the individual is not a particular substance, as in the Aristotelian tradition, but “a thing that exists in such a way that it needs no other to exist.” The substance is characterized by its independence and arises with consciousness as an innate idea. There are 3 substances: “the infinite thing,” the thinking thing, conscious mental activity; and “the extended thing,” something measurable. Each substance manifests a series of attributes. In the realm of the finite, he radically separates the spiritual from the material, granting mental freedom to the world, which is deterministic. Both substances depend on a mechanism of bodies. * God and the justification of the method: The steps of the deductive process are: the doubt approach: theoretical, universal, methodical; the cogito: “I think, therefore I am,” the first truth; the idea of infinity; the demonstration of God’s existence; and the criterion that ensures truth. Descartes begins by doubting everything that can be doubted. There are 3 great fields of doubt: “sensitive information,” which can be erroneous; the existence of things, which could be a result of fantasy; and the capacity of human reason to know the truth. The first doubt leads to the famous “I think, therefore I am.” An innate idea of the thinking substance is identified with God. From the infinite idea, he proves the existence of God. God validates the criterion of truth, eliminating the evil genius hypothesis and guaranteeing the existence of external reality. 2-The relationship between body and spirit. Cartesian anthropology is dualistic: the human being is composed of the self and the body, thinking substance and extended substance. The human body is a machine, its fundamental attribute being extension. The self manifests itself in various ways, such as understanding, memory, imagination, and will. The problem is the interaction between body and spirit. Descartes locates this interaction in the brain.
David Hume: A Moderate Skeptic
DAVID HUME. * A moderate skeptic: Hume’s empiricism does not value metaphysical terms. Sensitive information is the only valid source of knowledge. Math and logic are valid but do not provide knowledge of the world. Empirical science only provides probable hypotheses, never accurate truths. * Human nature and knowledge: All human knowledge is related to the science of human nature, which is the foundation of all other sciences. All sciences are based on experience and observation. Theory of knowledge: Hume addresses impressions and ideas. The study of the human understanding is a psychological analysis. Not all mental content has the same force. Impressions are first, and ideas are second. * The association of ideas: Complex ideas originate from simple ideas through mental laws. The most frequent mental operations are: similarity, contiguity in space and time, and causal relationship. * Types of knowledge: Relations of ideas are formal sciences like mathematics, whose propositions are analytical. The truth is that the contrary proposition is contradictory. The truth does not depend on empirical experience. Matters of fact are empirical sciences like physics, whose propositions are synthetic. The truth is probable and based on experience. * Analysis of causality: To explain an event, it is necessary to find its natural causes. Rationalists see God as the cause of the world. Empiricists deny access to the substance of things. We only have appearances. * Causality, habit, and belief: Causal inference is acceptable if it has empirical support. The only thing we have is the constant conjunction of impressions. Inferences about the future are based on habit and cannot be justified rationally. This does not affect ordinary life. * Critical concept of substance: The external world does not have constancy and coherence beyond our impressions. We cannot know things in themselves. We believe in the continuous existence of bodies due to imagination. We cannot assert the existence of the self as a substance. God’s existence cannot be demonstrated through experience. Hume’s theory is a moderate skepticism. Human understanding affects theoretical knowledge but not practical life. Human life only reaches probable truths, and we must be humble and tolerant.