Explanation
Impressions and ideas
The distinction concerns force and vivacity, not two separate worlds. Remembering pain and feeling pain may share content while differing dramatically in experiential presence.
The copy principle
Tracing ideas to impressions is both a psychological hypothesis and a method of criticism. Its difficulty lies in complex concepts assembled, abstracted or transformed beyond any single experience.
The missing shade
Hume admits that someone could imagine one unexperienced shade between familiar colours. His willingness to preserve the counterexample shows that the principle is general rather than exceptionless.
Relations of ideas and matters of fact
This division anticipates later distinctions between analytic or necessary truths and contingent empirical claims. The categories differ in what establishes them and what it means to deny them.
Why causation matters
Memory and present sensation reach only what is immediately given. Every inference to absent objects, past events or future outcomes relies upon causal reasoning.
The problem of induction
Past regularity does not logically entail future regularity. Demonstration cannot establish uniformity, and experiential justification becomes circular. The problem concerns rational foundation, not the practical usefulness of prediction.
The sceptical solution
Hume replaces justification by mechanism at a key point. Custom explains why expectation occurs and why it is unavoidable, even though it does not convert induction into demonstrative proof.
Belief as a manner of conception
A believed proposition may contain the same basic ideas as an imagined one. What differs is the steadiness and vivacity supplied by connection with impressions and habit.
Probability and calibrated confidence
Evidence admits degrees. Contrary cases divide expectation, making Hume’s approach relevant to probabilistic reasoning even though it predates modern formal probability.
Necessary connexion
We observe events following events, never a sensory bond compelling the second. Necessity becomes regular succession plus the mental transition created by repeated experience.
Humean laws of nature
On a common interpretation, laws summarise stable patterns rather than govern events through hidden powers. Whether Hume denies real powers or only denies our knowledge of them remains debated.
Compatibilism
Freedom does not require actions without causes. It requires conduct flowing from the agent’s will rather than external compulsion. Predictable character is what makes responsibility intelligible.
Animal reasoning
Continuity between human and animal learning supports a naturalistic psychology. Sophisticated inference grows from mechanisms visible in non-verbal creatures, not from pure logical demonstration.
Testimony as evidence
Hume does not reject testimony generally. Social knowledge depends upon it. Reports are weighed against background regularity, witness quality and alternative explanations.
What counts as a miracle
A rare event is not automatically miraculous. A miracle violates a law supported by uniform experience, making the evidential burden exceptionally high.
Religion and competing testimony
Miracle stories from rival traditions undermine one another when each supports incompatible doctrines. Cultural enthusiasm and transmission add further possibilities of error.
Proportional inference
An observed effect licenses only attributes necessary to explain it. Inferring an infinitely perfect cause from a finite mixed world goes beyond the evidence and cannot justify new predictions.
Mitigated scepticism
Hume rejects both dogmatism and total suspension. Awareness of fallibility should moderate confidence and focus inquiry without preventing ordinary reasoning and action.
Naturalism and reason
Human nature supplies practices that abstract reason cannot independently ground. Philosophy becomes the study and refinement of these unavoidable operations rather than an attempt to escape them entirely.
The closing “commit it to the flames” passage
The statement targets works with no demonstrative or experiential content. Its rhetoric is stronger than Hume’s own broad practice, which values history, morals and criticism when grounded in human experience.