Descartes's Rationalism: Foundations of Modern Knowledge

Descartes's Quest for Knowledge and Method

Our understanding of reality stems from various sources. While empiricism posits that knowledge originates from our senses, rationalism asserts that true and valid knowledge about reality is derived from reason. This rationalist perspective, particularly as championed by René Descartes, is deeply connected with the foundational ideas of modern science, emphasizing deduction. For Descartes, our knowledge of reality can be established deductively from certain self-evident ideas and principles, which he considered innate.

Background to Descartes's Philosophy

• 1. Motivations for a New Method

  • Negative Motivation: Descartes was critical of his contemporary educational environment, which he found to be based on rote repetition and rigid tradition. He believed this approach hindered the acquisition of new knowledge and lacked a systematic, reliable method for discovery.
  • Positive Motivation: Descartes was inspired by the rapid advancements in experimental methods within physical sciences and astronomical work, notably by figures like Johannes Kepler, Nicolaus Copernicus, and Galileo Galilei. He observed that these breakthroughs were fundamentally grounded in mathematics, which, unlike traditional scholastic methods, fostered innovation rather than mere repetition. Descartes sought to apply a similar mathematical rigor to philosophy.

• 2. Critique of Deductive Syllogism

  Descartes, along with Francis Bacon, precisely sought a new method that would characterize the modern age, moving beyond the limitations of traditional scholastic thought. They aimed to replace the prevailing world of ideas and beliefs with a new method capable of explaining fundamental facts of nature, as well as the spiritual and social life of humanity. A new criterion of truth was needed to supersede Aristotle's syllogism, which, while useful for organizing existing knowledge, could only be applied provided a general truth was already known. Scholastic syllogistic reasoning primarily served to deduce particular cases from general principles, often derived from revealed truth or faith. It was not designed to discover new truths or generate novel insights.

  Both Descartes and Bacon were leading critics of the syllogism, holding it responsible for the perceived stagnation of science. Bacon famously stated that Aristotelian logic was "useless for invention." Descartes concurred, arguing that the syllogism was ineffective for investigating truth; its primary utility lay in merely facilitating the exposition of what was already known to others.

• 3. Influence of Mathematics: The Mathematical-Analytical Method

  • a. Mathematical Aspect: Descartes's method is profoundly mathematical because he adopted mathematics as his model for rigorous inquiry. This approach is founded on two fundamental concepts: order and measure.
  • b. Analytical Aspect: For Descartes, the analytical process gave primacy to the simple over the complex. He believed that true understanding comes from breaking down complex problems into their simplest, most fundamental components. Only these simple components possess clarity and distinctness.
    • Clarity: Anything that is not identical with itself, or that appears obscure and confused, is considered "dark" or unclear to us. A good logical inference, according to Descartes, is one that leads to the establishment of an identity or a tautology between ideas, ensuring their clear and distinct perception.