Hume, Descartes, and Kant: Key Philosophical Concepts

Posted on Feb 28, 2025 in Philosophy and ethics

Hume’s Perceptions: Impressions and Ideas

Hume further divides perceptions into impressions and ideas:

  • Simple Perceptions: These do not allow any distinction or separation and cannot be divided into simpler components. Examples include color, flavor, or any singular sensory experience.
  • Complex Perceptions: These can be divided into parts. For example, the combined perception of color, flavor, and odor.

There are no innate ideas: All ideas originate from experience, specifically from impressions. Impressions are more vivid and stronger than their corresponding ideas.

Critique of Metaphysics

Hume’s method involves analyzing impressions and their corresponding ideas to understand knowledge. He identifies two types of impressions:

  • Impressions of Sensation: Perceptions that arise from unknown causes. We experience them without knowing their origin.
  • Impressions of Reflection: Impressions caused by ideas. Recalling an idea can produce a new impression, which in turn generates another idea.

Phenomenalism and Skepticism

Phenomenalism: Only phenomena, what appears in our minds, are real; everything else is speculation. Skepticism: Hume questions humanity’s ability to attain truth, consistently applying this doubt throughout his reasoning.

Descartes’ Method

First Rule of Evidence: Accept only what is undoubtedly true. Avoid haste and accept only clear and distinct ideas.

Second Rule: Analysis: Break down complex problems into simpler, well-defined parts, excluding unnecessary or inaccurate information.

Third Rule: Synthesis: Reconstruct a chain of partial insights from simple and intuitive ideas to achieve a clear and error-free understanding.

Fourth Rule: Enumeration: Review the entire process to ensure nothing is missed.

Methodical Doubt: The Cogito

Doubt is not a permanent state but a tool to reach truth and build a reliable system of knowledge. This doubt is:

  • Universal: Everything must be doubted.
  • Theoretical: Limited to the level of theory, not extending to beliefs or ethical behavior.

Descartes’ Application of Methodical Doubt:

  • Doubting the Senses: Senses can deceive us, so we cannot fully rely on them.
  • Doubting the External World: It’s not always possible to distinguish reality from dreams.
  • Doubting One’s Reasoning: Our understanding can err, even in mathematical proofs.
  • Doubting Oneself: The possibility of an evil genius leading us to error.

Cartesian Metaphysics: The Three Substances

  • Res Cogitans: The thinking self (soul).
  • Res Infinita: The perfect being, or God.
  • Res Extensa: External reality or the world.

Kant’s Ethical Framework

Material Ethics

Material ethics is:

  1. Based on the idea that there are goods, i.e., things beneficial for humans, starting with identifying the highest good.
  2. Actions are judged as good or bad based on whether they lead us closer to or further from that good.
  3. It establishes rules and precepts to guide actions, making it “material” due to its content.

Critique of Material Ethics

Kant critiques material ethics on the following grounds:

  • Empirical and A Posteriori: Precepts are derived from experience.
  • Teleological and Hypothetical: Pursues an end, and requirements are conditional to achieving it.
  • Heteronomous: For an action to be moral, the will must be autonomous, i.e., under its own law.

Formal Ethics

  1. A Priori and Universal: Based on something common to all.
  2. Explicit, Absolute, and Unconditional: Disregarding ends, circumstances, or consequences.
  3. Autonomous: Based on the subject’s structure, independent of external factors. The moral law determines good and bad, not vice versa.
  4. Formal: Devoid of all content.