Scepticism and the Limits of Knowledge
Understand philosophical scepticism and evaluate whether radical doubt can be answered.
How to study A-level Philosophy
Learn each position as an argument, connect it to its strongest objection and reply, then decide what conclusion the dialectic supports.
Core concepts
Concept 1
Philosophical scepticism systematically challenges whether knowledge is possible and may be local or global.
Exam cue: State the scope of the sceptical conclusion rather than claiming that nothing is knowable.
Concept 2
Descartes's waves of doubt use illusion, dreaming and an evil demon to challenge increasingly basic sources of belief.
Exam cue: Explain whether a response disproves the scenario, shows it irrelevant or weakens the demanded standard.
Concept 3
Responses include rationalist certainty, Locke's sensitive knowledge, Berkeleyan idealism, Russell's best hypothesis and reliabilism.
Exam cue: Compare internal access to reasons with external reliability.
Targeted study blocks
Specified core
Secure the claim and its place in the debate
Reconstruct Descartes's three waves of doubt and compare the replies offered by the principal realist, idealist, rationalist and reliabilist positions.
Philosophical work
Reconstruct, challenge and judge the argument
For each response, specify the sceptical premise it targets and whether it restores certainty, knowledge or only reasonable belief.
Risk pitfalls and guardrails
Confusing normal caution or incredulity with philosophical scepticism.
Guardrail: Do not replace philosophical reasoning with quotation, biography, intuition or a philosopher's name.
Assuming a sceptical possibility is probable merely because it cannot be ruled out.
Guardrail: Do not replace philosophical reasoning with quotation, biography, intuition or a philosopher's name.
Using common sense as a reply without showing why it has epistemic force.
Guardrail: Do not replace philosophical reasoning with quotation, biography, intuition or a philosopher's name.
Memory anchors
Local scepticism
Local scepticism targets knowledge in a limited domain.
Global scepticism
Global scepticism targets knowledge across nearly all domains.
Dreaming argument
The dreaming argument challenges whether present experience guarantees wakefulness.
Evil demon
The evil-demon hypothesis imagines systematic deception even in apparently rational thought.
Best hypothesis
Russell argues that a mind-independent world is the best explanation of ordered experience.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
What is philosophical scepticism about the external world?
What role does Descartes's method of doubt play?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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