Rationalism vs. Empiricism: Descartes' Quest for Certainty

Rationalism vs. Empiricism: Core Tenets

Shared Ground and Key Differences

Rationalism and empiricism share common ground:

• The subject is central, deciding the truth or falsity of statements.
• Both begin with an analysis of knowledge to determine its scope.

However, they diverge significantly. Rationalism places the criterion of truth in the autonomy of reason, constructing knowledge deductively from innate principles, independent of sense experience. Conversely, Empiricism starts with experience and uses induction to reach explanatory hypotheses about phenomena.

Descartes: A Rationalist Landmark

Influence and Platonic Parallels

René Descartes profoundly influenced his era and subsequent philosophy. His work fits within a philosophical lineage, connecting Plato and scholastic thought.

Comparisons can be drawn with Plato, particularly regarding their dualistic conception of reality. However, for Descartes, thinking substance (mind) and bodily substance (matter) are independent. Furthermore, unlike Plato's Forms, the Cartesian subject is not a transcendent reality. Both philosophers distrust the senses as a source of certain knowledge, though for different reasons: Plato emphasized the changing nature of the sensible world, while Descartes noted that the senses sometimes deceive us. Reason, for Descartes, is the sole faculty capable of grasping truth, particularly self-evident, obvious truths (clear and distinct ideas).

Contrasts with Aristotle and Aquinas

Descartes' epistemology differs radically from that of Aristotle. Similarly, his approach contrasts with St. Thomas Aquinas. While Aquinas argues for God's existence based on observations of the world (a posteriori), Descartes bases his proof on the innate idea of infinity (a priori).

The Central Epistemological Debate

Reason vs. Senses in Accessing Reality

A key distinction from ancient and medieval philosophy lies in the relationship between our mental representations and external reality. Early modern Rationalism (epitomized by Descartes) and Empiricism engaged in intense debate over this problem. Given that the subject does not perceive reality directly, knowledge must be accessed via either reason or the senses. Rationalists champion reason as the reliable path, while Empiricists maintain that all knowledge originates from and is justified by experience.

Bridging the Divide: Kant's Synthesis

Immanuel Kant later synthesized these opposing views to some extent. He proposed that while knowledge begins with experience, the subject's understanding actively structures that experience through innate categories.

Modern Echoes: Husserl's Phenomenology

More recently, Edmund Husserl, influenced by Descartes, revived aspects of this focus. Rejecting naturalism and psychologism, Husserl's phenomenology 'brackets' the question of external reality's existence to concentrate on the structure of consciousness itself.