John Locke on Primary and Secondary Qualities
Overview
- John Locke: Empiricist (tabula rasa, blank slate)
- Distinction between Primary and Secondary Qualities
- Arguments supporting the distinction
- His view of the material world
Empiricism vs. Rationalism
- Empiricists (e.g., Hobbes, Locke): Knowledge comes from sensory experience. Babies are born as blank slates.
- Rationalists (e.g., Descartes): Innate ideas are hardwired into the mind from birth.
Skepticism of the Senses
- Locke acknowledges Descartes' skepticism: Senses might deceive us (dreams, brain-in-a-vat scenarios)
- Locke still believes sensory experience is foundational
- Descartes’ rational response: Cogito ergo sum (I think therefore I am), existence of a non-deceptive God
Locke’s Argument on Senses and Reality
- Argument for senses: Sensations reinforce each other (e.g., sight and touch confirm object’s existence)
- Contradiction in Sensations: Dreams vs. reality, but sensations cohere in waking life
Material World According to Locke
- Qualities: Inherent features of matter
- Primary Qualities: Solidity, extension, figure, motion
- Secondary Qualities: Color, taste, sound, which are not actually inherent in objects
- Substance: A necessary, imperceptible support for qualities
- Similar to the concept of dark matter in contemporary physics
Primary vs. Secondary Qualities
- Primary Qualities: Inherent, inseparable from matter, detectable through multiple senses
- Secondary Qualities: Not actually present in objects, result from primary qualities interacting with senses
- Example: Color is an effect caused by primary qualities (e.g., texture causing light reflection)
Perception and Reality
- Causal Theory of Perception: Primary qualities cause sensations, secondary qualities are effects
- Locke’s experiment: Multiple sensations confirm reality (e.g., hot and cold water experiment)
- Heat and Cold: Caused by molecular motion, not properties of objects
- Pain: Sensible idea caused by an external object, doesn't resemble the object
Practical Examples
- Stick hand in fire: Sensation of pain proves pain isn't in fire
- Water tub experiment: Sensation of temperature varies based on previous exposure
- Almond example: Pounding affects secondary qualities like taste, not primary qualities like matter
Importance of Primary Qualities
- Shape and motion of molecules cause secondary qualities
- Example of a pen: Solidity, extension vs. color, taste
Conclusions
- Ideas of Primary Qualities: Resemble the actual qualities in objects
- Ideas of Secondary Qualities: Do not resemble any actual qualities in objects, are effects caused by primary qualities
Summary: Locke supports the existence of a material world grounded in primary qualities. Secondary qualities are sensory effects without real counterparts in objects, demonstrating the complexity of perceived vs. actual reality. This setup provokes further philosophical inquiry, as seen with later philosophers like Berkeley.
Key Terms: Empiricism, Rationalism, Primary Qualities, Secondary Qualities, Substance, Causal Theory of Perception