Discourse on the Method of Rightly Conducting One’s Reason and of Seeking Truth in the Sciences (1637) Informative Summary


Descartes, dissatisfied with the traditional scholastic approach to knowledge, embarked on a quest for truth based on reason and doubt. He meticulously sought to dismantle all previously held beliefs, starting with the certainty of his own existence, famously articulated in the phrase “I think, therefore I am.” This foundational principle, coupled with the idea of God as a perfect and benevolent being, forms the basis of his philosophy.

Descartes then applied his methodical approach to understanding the physical world, envisioning a hypothetical “new world” created by God. He analyzed the laws of nature governing the interaction of matter, explaining phenomena such as the movement of the heavens, the formation of the earth, and the properties of light and heat. He explored human beings as intricate machines, theorizing about the mechanics of the heart and arteries.

Key Findings:

  • The Power of Doubt: Descartes argues that by systematically doubting everything, we can arrive at truths that are unshakeable.
  • Cogito Ergo Sum: The most fundamental truth, “I think, therefore I am,” is the starting point for all other knowledge.
  • The Existence of God: Through reason, Descartes establishes the existence of God as a perfect and benevolent being, the source of all truth and reality.
  • Mind-Body Dualism: He posits a clear distinction between the immaterial mind and the physical body, suggesting that the mind is distinct from and more easily known than the body.
  • Mathematical Model for Knowledge: Descartes proposes that mathematics, with its demonstrable certainty, serves as a model for acquiring knowledge in all areas.


  1. The “Cogito” is a self-evident truth: This is because the very act of doubting one’s existence implies that one is existing, thinking about that doubt.
  2. The mind is distinct from the body: Descartes argues that the mind can be conceived of independently of the body, proving its unique essence.
  3. God is a perfect being: This is implied by the very idea of a perfect being, which necessarily includes existence as a perfection.
  4. Everything that we know comes from God: Descartes believes that God, being perfect and the source of all creation, is the ultimate source of our knowledge and ideas.
  5. Doubt is a tool for discovering truth: By systematically doubting, we eliminate false beliefs and arrive at firmer conclusions.
  6. The world is governed by natural laws established by God: These laws are not arbitrary but reflect God’s perfect and rational nature.
  7. The universe is a machine governed by mechanical principles: Descartes’ understanding of the physical world is based on mechanical and mathematical principles, influenced by the burgeoning scientific revolution.
  8. The human heart is a mechanical pump: He accurately describes the heart’s function as a pump, influenced by the recent anatomical discoveries of his time.
  9. Animals are purely mechanical beings: Descartes believes that animals lack a rational soul and are driven solely by instinct and mechanical processes.
  10. Light travels in an instant: While not completely accurate, Descartes believed that light travels instantaneously, a reflection of the limited understanding of the speed of light at the time.
  11. The earth’s gravity is independent of its weight: He theorized that gravity exists even in the absence of weight, a concept reflecting the development of early ideas about gravity.
  12. The tides are caused by the moon: Descartes correctly attributes the tides to the moon’s gravitational pull, though he lacked the precise understanding of gravity later developed by Newton.
  13. Heat is a form of fire without light: He understood that heat could exist without visible light, demonstrating some insight into the nature of energy.
  14. Glass is formed from the intense heat of ashes: This observation highlights Descartes’ interest in scientific experimentation and the relationship between matter and heat.
  15. The human body is a machine: Descartes’ view of the body as a complex machine, controlled by a rational soul, was influential in shaping later scientific thinking.
  16. The soul gives humans their unique characteristics: He believed that the soul is responsible for our ability to reason, think, and feel, setting us apart from animals.
  17. The human senses can be deceived: Descartes emphasizes the fallibility of human perception and the importance of relying on reason to determine truth.
  18. Reason is a tool for overcoming the limitations of our senses: He believed that reason, not just sensory experience, is essential for understanding the world.
  19. Knowledge is a continuous process of improvement: Descartes saw the pursuit of knowledge as an ongoing process of refining our beliefs and reaching a closer approximation of truth.
  20. It is more likely that God created the world as it is, rather than through a gradual process: While he described the creation of a “new world” through natural laws, he acknowledges that God could have simply created the world in its current state.


  1. Nine years: The length of time Descartes spent traveling and reflecting before settling down to write his Discourse.
  2. Twenty-three years old: Descartes’ age when he began his serious philosophical inquiry.
  3. Eight years: The duration of Descartes’ solitary retreat in Holland before publishing his Discourse.
  4. Three or four maxims: The number of principles comprising Descartes’ provisional code of morals.
  5. Two or three months: The time Descartes dedicated to mastering mathematical concepts.
  6. Four precepts: Descartes’ core methodological principles: clarity and distinctness, division, order, and enumeration.
  7. Hundreds of pages: The estimated length of the treatise Descartes planned to write containing his scientific discoveries.
  8. One instant of time: Descartes’ belief that light travels instantaneously across vast distances.
  9. Thousands of years: The timeframe over which the matter of the “new world” gradually organizes into a cosmos.
  10. No weight: The initial assumption Descartes makes regarding the matter of the earth in his description of the “new world”.
  11. From east to west: The direction of the current of air and water that Descartes predicted in his hypothetical world.
  12. Many parts: The diversity of elements that constitute the earth, according to Descartes’s model.
  13. One fire: The source of heat in the human body that Descartes identified, similar to the fire in fermenting wine.
  14. Infinite perfection of God: The foundational principle used by Descartes in his scientific explanations.
  15. One single body: The shared material nature of all bodies, according to Descartes.
  16. One single soul: The individual and unique nature of the human soul, which Descartes considered distinct from the body.


  1. Cogito ergo sum: (Latin for “I think, therefore I am”) – This is Descartes’ most famous phrase, expressing the fundamental truth of his own existence.
  2. Method: A systematic approach to knowledge, involving doubt, reason, and clarity of understanding.
  3. Substance: A thing that exists independently, with its own essence or nature.
  4. Dualism: The philosophical idea of a separation between mind and matter.
  5. Innate ideas: Ideas that are not derived from experience but are inherent in the human mind.
  6. Rationalism: A philosophical approach that emphasizes the role of reason in acquiring knowledge.
  7. Skepticism: A philosophical position that questions the possibility of certain knowledge.
  8. Perfect Being: An ideal being that possesses all perfections, including existence.
  9. Mechanical philosophy: A view of the universe as a machine governed by physical laws.
  10. Natural laws: Rules governing the behavior of matter and the universe, established by God.


  1. The “Cogito” as an example of self-evident truth: The very act of doubting one’s existence proves that one must exist to doubt.
  2. Dreaming as an example of the fallibility of senses: Our senses can deceive us, as evidenced by the vivid illusions we experience in dreams.
  3. The geometrical triangle as an example of a mathematical object: Descartes uses the triangle to illustrate how mathematics offers certain knowledge through clear and distinct reasoning.
  4. The idea of God as an example of an innate idea: Descartes argues that the idea of a perfect being is not derived from experience but exists within the mind.
  5. The human heart as an example of a mechanical system: Descartes provides a detailed mechanical explanation for the functioning of the heart.
  6. The flow and ebb of the tides as an example of natural law: Descartes attributes the tides to the gravitational pull of the moon, illustrating the influence of celestial bodies.
  7. The formation of glass from ashes as an example of scientific observation: Descartes demonstrates his interest in experimental science by describing this remarkable transmutation.
  8. The ability to reason as an example of the human soul’s unique power: Descartes believes that the soul, distinct from the body, is responsible for our capacity for thought and reason.
  9. A person in the jaundice seeing everything as yellow as an example of sensory deception: This illustrates how our perceptions can be distorted, highlighting the need for reason.
  10. A chimaera as an example of a figment of the imagination: Descartes argues that we should not accept the existence of things based solely on what we imagine.

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