Descartes’ Philosophy: A Path to Certainty

Posted on Mar 21, 2025 in Philosophy and ethics

Introduction: Descartes’ Discourse on Method

This piece delves into Descartes’ masterpiece, *Discourse on Method*, a philosophical work that seeks to answer every question posed, aiming to find a universal science applicable to all.

The Method (Part II)

Descartes developed a method based on mathematics and logic to achieve true knowledge. It comprises four rules:

  1. Evidence: Intuitively recognizing something as true, carefully avoiding haste and bias—the two errors of doubt—and accepting only what is presented so clearly and distinctly to the mind that there is no reason to doubt it. This includes explaining methodical doubt.
  2. Analysis: Breaking down complex ideas into simpler ones, allowing for intuitive understanding.
  3. Synthesis: Ordering thoughts, starting with the simplest and easiest-to-understand concepts and progressing to the most complex.
  4. Enumeration: Thoroughly reviewing to ensure no complex ideas have been overlooked.

Application of Universal Doubt (Part IV)

To find the self-evident, Descartes began by doubting everything. He applied doubt to:

  • The senses, as they can be unreliable.
  • Arguments, because humans can make reasoning errors.
  • The distinction between waking and sleeping.

He posited that everything we have known might be false, introducing the idea of an “evil genius” deceiving us, making good appear evil and vice-versa. This doubt is universal, orderly, voluntary, theoretical, and provisional.

Having questioned everything, Descartes arrived at the indubitable truth: Cogito, ergo sum – “I think, therefore I am.” This establishes the existence of the self as a thinking entity, rather than a mere collection of thoughts.

Demonstration of the Existence of God (Part IV)

The author, confined to the self, uses this to demonstrate God’s existence. Descartes presents three arguments:

  1. We are imperfect because we doubt.
  2. We possess ideas of perfection, which must have been placed in us by a perfect being, as we could not have created them ourselves.
  3. The ontological argument: God possesses all perfections, including existence; therefore, God exists.

Ideas of God (Part IV)

The idea of God cannot be adventitious (from external sources), as everything known from the outside is less perfect than the self. Nor can it be factitious (constructed), because the effect cannot be greater than the cause. Therefore, it is innate, placed within us. God is objective and provides us with evidence; therefore, God is true, good, and does not deceive us.

Descartes identifies three types of substances: God (the only true substance), res cogitans (thinking substance, the mind), and res extensa (extended substance, the body). The problem arises with the mind-body union, as each substance is autonomous. Although there is a substantial union between the latter two, they are distinct. Descartes proposed that their union occurs in the pineal gland.

Conclusion

Descartes’ goal was to find a universal science. He metaphorically described this through the *tree of science*, where the roots are metaphysics (the self, God, the external world), the trunk is physics, and the branches/fruits are the practical sciences (medicine, ethics, mechanics).