Key Ideas
1. Philosophy should unite depth with clarity
Abstract inquiry is valuable when it improves judgement and remains connected with common life.
2. Impressions are more vivid than ideas
Present sensation and emotion possess greater force than memory or imagination.
3. Ideas generally copy impressions
The materials of thought originate in prior experience even when imagination rearranges them.
4. Obscure concepts should be traced to experience
A term lacking any identifiable impression may have no clear philosophical content.
5. Ideas associate through three relations
Resemblance, contiguity and cause and effect guide transitions of thought.
6. Relations of ideas are necessarily true
Their denial entails contradiction and their truth does not depend upon actual events.
7. Matters of fact are contingent
The opposite of any empirical claim remains conceivable without formal contradiction.
8. Causal knowledge is learned
No unfamiliar cause reveals its effect through pure inspection alone.
9. Induction lacks non-circular proof
Past regularity cannot justify future uniformity without already relying upon inductive reasoning.
10. Custom produces expectation
Repeated conjunction trains the mind to anticipate one event after another.
11. Belief is a lively conception
Believing differs from merely imagining through force, steadiness and connection with experience.
12. Probability admits degrees
Mixed evidence and unequal frequencies distribute confidence rather than creating certainty.
13. Necessary connexion is not sensed in objects
Experience supplies regular succession, while habit supplies the inferential transition.
14. Liberty and necessity are compatible
Actions can follow stable motives while remaining free when they express the agent’s will without constraint.
15. Animals reason through experience
Their learned expectations support a natural rather than demonstrative account of causal inference.
16. Belief should be proportioned to evidence
Testimony, regularity and alternative explanations must be weighed comparatively.
17. Miracles face an exceptional evidential burden
A report must outweigh the established experience supporting the relevant law of nature.
18. Causes should not be enlarged beyond effects
Observed results license only proportionate attributes in whatever cause is inferred.
19. Extreme scepticism cannot govern life
Human nature restores belief and action even when philosophical doubt becomes powerful.
20. Mitigated scepticism restrains dogmatism
Recognising cognitive limits encourages modest confidence and inquiry suited to human capacities.