PHIL190 - CLASS 2: Comprehensive Study Notes on Epistemology, Cartesian Doubt, and Rationalism

Direct Empirical Evidence

Knowledge acquired through direct sensory perception and observation of physical objects, events, or environments.

Testimony

Knowledge acquired through the statements, reports, or claims of other individuals, whether oral or written.

Pure Rational Thought

Knowledge derived from internal logical reasoning, critical conceptual analysis, and a priori inference rather than sensory data.

Actual Doubt vs. Possibility of Doubt

Actual doubt is currently experiencing suspicion about a belief, whereas possibility of doubt is the ability to conceive a hypothetical scenario in which a belief could be false.

The Cogito ($\text{Cogito, ergo sum}$)

Descartes' foundational certainty that the very act of thinking or doubting logically guarantees the existence of the experiencing subject.

Extended Substance ($\text{res extensa}$)

Physical matter and bodies characterized by spatial extension and governed by mechanical laws.

Thinking Substance ($\text{res cogitans}$)

The non-extended mind or soul characterized by conscious thought and reflection.

Method of Doubt

The philosophical methodology of withholding assent from any opinion that is not completely indubitable in order to find absolute foundations for knowledge.

Dream Argument

The skeptical argument that because waking experiences lack definitive operational marks distinguishing them from vivid dreams, sensory perceptions are unreliable for establishing absolute certainty.

Evil Demon Hypothesis

A radical skeptical thought experiment positing an all-powerful deceiver to show that even basic mathematical truths and logical intuitions could hypothetically be false.