Descartes and Locke: Rationalism and Empiricism

Descartes' Project (Overview)

• Philosophy focuses on three primary subjects:

  • God

  • Self

  • World

Descartes' Approach to Proving Existence

• Descartes begins his philosophical journey from doubt and aims to establish the certainty of:

  • Self

  • "Cogito, ergo sum" meaning "I think, therefore I am."

  • Establishes the self as a thinking entity.

  • God

  • The self, as a thinking being, offers thoughts reflecting on ideas within the mind.

  • Found an idea of a perfect being which cannot be self-generated or produced by an evil demon.

  • This idea of perfection implies the existence of a perfect being, as causes must be greater than their effects, linking to the Ontological Argument.

  • World

  • Not discussed in detail but noted as significant.

Trusting Perceptions of the World

• Importance of trusting perceptions is acknowledged, although not covered in detail.

• Doubt about accuracy in perceptions leads to the seeking of a definitive conclusion.

• As a scientist, Descartes emphasizes the need for reliability in senses for scientific endeavors.

Argument on Reliability of Perceptions

• Since a perfect God exists, one can trust that:

  1. An evil demon cannot be deceiving thoughts (perfect God wouldn't allow it).

  2. The senses can be generally trusted (a good God wouldn't create unreliable means of gaining knowledge).

• Concludes:

  • Physical things represented by clear and distinct ideas (like the body) must exist.

  • While errors can occur, there is enough confidence in senses as a way to attain knowledge.

Rationalism

• Descartes' epistemology is categorized as Rationalism.

Key Aspects of Rationalism

• Primacy of Reason:

  • Reason is regarded as the most reliable source of knowledge.

  • Trust in senses is conditioned by what reason dictates; conflicts are resolved in favor of reason.

• Dualism:

  • Fundamental division into two entities: material (physical) and non-material (spiritual).

  • The non-material aspect is superior, as it doesn't decay or break down.

• Innate Ideas:

  • These ideas exist within humans from birth.

  • First and foremost would be the idea of God.

  • Other potential innate ideas include self, logic, mathematics, and ethical principles.

Indirect Realism

• Exploration of Indirect Realism is postponed for later discussion.

Descartes' Notorious Dualism

• Often referred to as Cartesian Dualism, distinct from Plato's ideas.

• The Mind-Body Problem:

  • The existence of mind (non-physical) alongside body (physical).

  • Interaction between mind and body is essential:

  • Mind affects body (i.e., ability to will actions).

  • Body influences mind (i.e., physical injuries affecting memory and perception).

• Descartes theorized that the mind is situated in the pineal gland.

John Locke

• Overview of Rationalists vs. Empiricists

• Rationalists include Descartes, Leibniz, and Spinoza - all from Continental Europe.

• Key Themes in Rationalism:

  • Reason is the primary source of knowledge.

  • Reliance on reason over senses in conflict situations.

  • Acceptance of innate ideas.

• Empiricists like Locke, Berkeley, and Hume stem from Britain/Ireland, arguing:

  • Both reason and experiences are trustworthy but deny innate ideas.

  • The mind starts as a "tabula rasa", blank slate, requiring experience to acquire ideas.

Locke's Essay (Concerning Human Understanding)

Chapter 1: Introduction

1. The inquiry into the human mind is essential as it differentiates humans from animals.

2. Focus on understanding origin, certainty, and scope of knowledge, while avoiding the mind-body connection (acknowledging Descartes' unresolved issue).

3. Locke identifies as a dualist.

Chapter 2: Neither Principles nor Ideas Are Innate

1. Argument against innate ideas:

   • Presenting a clear explanation of idea generation.

2. Critique on the argument for innate ideas based on universal consensus:

   • Universality does not confirm innateness. Example regarding dogs and animals demonstrates a false converse.

3. Challenge to universal logical principles claimed by innatists:

   • Locke recognizes that not all agree on foundational logical phrases, thus dismissing the notion of innate ideas.

4. Discussion on how children and those in lower cognitive states support the non-existence of innate principles.

5. Addresses counterarguments about innate ideas emerging at the age of reason, labelling it as unsatisfactory.

6. Reminder that knowledge does not confirm innate qualities, as growth results in idea acquisition over time.

7. Concept of the mind as an "empty cabinet" being filled with ideas from experience, supporting statement that ideas deemed innate are merely clear and distinct to the rationalists.

Chapter 1: Of Ideas

1. Definition of Idea:Object of thought, encompasses concepts such as color, shape, and quality.

2. Origin of ideas solely rooted in experience, breaking down into:

   • Sensation: Information from the five senses.

   • Reflection: Introspection and internal mental processes.

3. Primary vs. Secondary Qualities:

   • Primary Qualities: Objective characteristics — extension, shape, size, motion that remain unchanged when divided.

   • Secondary Qualities: Subjective perceptions such as color and taste, which might differ across individuals and vanish when a substance is divided.

4. Acknowledges the discrepancy between perception and reality; senses can betray actual properties of the world.

Indirect Realism Explained

• Agreement between rationalists and empiricists on mind-body dualism.

• Framework of Indirect Realism:

  • Knowledge of the external world (physical) requires perception through senses, which are grounded in mental processes.

  • Explains interaction between the physical and mental by noting that perception is initiated by a physical stimulus (e.g., a tree).

• Indicates an intrinsic link between the physical and the incorporeal mind, essential for comprehension of perception and awareness within philosophical discourse.