Epistomology

1.3. Scepticism: The Challenge to Knowledge

Scepticism is a philosophical position that questions the possibility of knowledge. Sceptics argue that we cannot have certainty about anything. They raise doubts about our ability to know the external world, our own minds, or even basic truths of logic and mathematics.

Sceptics argue that justification is impossible due to:

1. Deceptive Senses: Our senses can deceive us. Illusions, dreams, and hallucinations can lead us to form false beliefs about the world. For example, a stick may appear bent when placed in water, but it is actually straight. Similarly, in a dream, we may experience events that are not real.

2. Infinite Regress: Every justification requires another justification, ad infinitum. This means that we can never reach a point where our beliefs are fully justified. For example, if we believe that the sky is blue because we see it as blue, we can then ask why we should trust our vision. This leads to an infinite regress of justifications.

Two Responses to Scepticism:

1. Empiricism: Empiricists claim that knowledge comes from sense experience. They argue that our senses provide us with reliable information about the world. Empiricists acknowledge that our senses can sometimes deceive us, but they maintain that we can correct these errors through careful observation and experimentation.

2. Rationalism: Rationalists claim that knowledge comes from pure reason. They argue that we can gain knowledge through intuition, deduction, and innate ideas. Rationalists believe that reason is a more reliable source of knowledge than sense experience. They point to the fact that our senses can be easily deceived, while reason is more consistent and reliable.

2. Empiricism: Sense Experience & Its Limits

2.1. Core Tenets of Empiricism

• Tabula Rasa (Locke): The mind is a "blank slate" at birth; all knowledge comes from experience.

• A Posteriori Knowledge: Knowledge derived from observation (e.g., "The sky is blue").

2.2. Sceptical Challenges to Empiricism

1. The Argument from Illusion (e.g., bent stick in water).

2. The Argument from Dreams (How do you know you’re not dreaming now?).

3. The Argument from Hallucination (e.g., drug-induced perceptions).

Empiricist Responses:

• Triangulation: Using multiple senses to verify observations.

• Normal Conditions: Assuming reliability in healthy, standard environments.

2.3. Hume’s Problem of Induction

• Induction: Reasoning from observed to unobserved (e.g., "The sun has risen every morning, so it will rise tomorrow").

• Hume’s Critique: Induction is invalid—past observations don’t guarantee future outcomes.

• Possible Solutions:

1. No True Scotsman: Rejecting counterexamples by redefining terms (unsatisfactory).

2. Principle of Uniformity of Nature (PUN): "The future resembles the past" (but how to justify PUN?).

3. Probabilism: Future events are likely based on past data (still invalid).

4. Popper’s Deductivism: Science progresses by falsifying hypotheses, not confirming them.

3. Rationalism: Reason as the Source of Knowledge

3.1. Descartes & the Cogito

• Method of Doubt: Reject all beliefs that can be doubted.

• Cogito Ergo Sum: "I think, therefore I am" — the one indubitable truth.

• Cartesian Circle: Descartes relies on God to guarantee clear & distinct ideas, but his proof of God depends on those very ideas.

3.2. Euclidean Geometry as a Rationalist Model

• Axiomatic Method: Start with self-evident axioms (e.g., "A straight line can be drawn between any two points").

• Synthetic A Priori Knowledge: Truths known independently of experience but not tautologies (e.g., "7 + 5 = 12").

Examples of Rationalist Aspiration:

• Hobbes: Applied Euclidean method to political philosophy (Leviathan).

• Einstein: Euclidean geometry inspired his confidence in pure reasoning.

3.3. Kant’s Synthetic A Priori & the Limits of Reason

• Kant’s Big Idea: The mind structures experience through innate categories (space, time, causality).

• Analogy of Rose-Tinted Glasses: We can’t perceive reality "as it is" (noumena), only as it appears (phenomena).

• Fishing Net Analogy (Eddington): We only "catch" what our cognitive "net" allows.

Implications:

• Space & Time: Not external realities but frameworks of human perception.

• Causality: We can’t experience uncaused events because causation is a mental category.

4. Challenges to Rationalism: Non-Euclidean Geometry & Einstein

4.1. The Fall of Euclidean Geometry

• Playfair’s Axiom: "Given a line and a point not on it, only one parallel line can be drawn."

• Alternative Geometries:

• Hyperbolic (angles sum to <180°).

• Elliptic (angles sum to >180°).

• Einstein’s Relativity: Space is non-Euclidean; Euclidean geometry is an approximation.

4.2. Implications for Rationalism

• Kant’s Mistake: He thought Euclidean geometry was synthetic a priori, but it’s not universally true.

• Empiricist Victory: The structure of space must be discovered a posteriori (through science).

5. Conclusion: The State of the Debate

5.1. Key Takeaways

1. JTB Theory is useful but flawed (Gettier cases).

2. Empiricism relies on senses but struggles with induction.

3. Rationalism relies on reason but overestimates a priori knowledge.

4. Kant’s Revolution: Knowledge is a collaboration between mind and world.

5. Modern Science favors empiricism but uses rationalist methods (e.g., math in physics).

5.2. Open Questions

• Can probabilistic reasoning justify induction?

• Does neuroscience support Kant’s categories?

• Is Popper’s falsificationism the best model for science?

These notes provide a detailed, exam-ready breakdown of PHIL 101’s epistemology unit, integrating lecture content, philosophical arguments, and critical analysis. For further depth, consult **Hume’s *Enquiry, **Kant’s *Critique of Pure Reason, and Popper’s Logic of Scientific Discovery