Overview
This lecture examines major theories of knowledge, focusing on empiricism, skepticism, and the classical "justified true belief" account, and explores key challenges to defining knowledge.
Empiricism and Locke's Three Kinds of Knowledge
- Empiricists like John Locke argued that knowledge begins with perception and sensation.
- Locke identified intuitive knowledge as truths known by understanding word meanings (e.g., a square is not a circle).
- Demonstrative knowledge comes from logical reasoning based on other knowledge (e.g., using triangle properties to understand the Pythagorean theorem).
- Sensitive knowledge is obtained directly through sensory perception (e.g., knowing there is a cat on the mat by seeing it).
- Locke believed concepts like justice arise from observing people and experiences, not just from intuition.
Hume's Skepticism
- David Hume was skeptical not of perception itself, but of assumptions about cause and effect.
- Hume argued we only observe events together (correlation) but cannot prove causation.
- He questioned the enduring self, claiming we only observe thoughts, not a persistent "self."
- Hume challenged arguments for miracles, seeing them as unsupported by usual experience.
- He did not endorse global skepticism; he believed doubting everything is impractical.
Justified True Belief and Its Problems
- Plato and later philosophers defined knowledge as "justified true belief": S knows P if P is true, S believes P, and S is justified in believing P.
- Truth in this context means the proposition corresponds with reality ("correspondence theory of truth").
- Gettier cases show problems with this account: someone can have a justified true belief without having knowledge (e.g., believing the correct time from a broken clock by coincidence).
- The issue of reliance on false beliefs complicates defining knowledge (e.g., a detective with mostly correct but one false testimony).
- Philosophers find it difficult to clearly define when a false belief undermines real knowledge.
Key Terms & Definitions
- Empiricism — the theory that knowledge comes primarily from sensory experience.
- Intuitive Knowledge — knowledge known immediately, often through understanding definitions or concepts.
- Demonstrative Knowledge — knowledge proven through logical reasoning from other knowledge.
- Sensitive Knowledge — knowledge gained directly through perception.
- Justified True Belief — the classical definition of knowledge as belief that is true and justified.
- Gettier Problem — situations showing that justified true belief may not always count as knowledge.
Action Items / Next Steps
- Review challenges to the justified true belief theory.
- Prepare to discuss potential solutions or alternatives to the Gettier problem for the next class.