Hume’s Enquiry (1748) is the clearest statement of empiricist philosophy and one of the most influential works in Western thought. It argues that all knowledge derives from experience and exposes the limits of human reason.
Impressions and Ideas
Hume distinguishes “impressions” (vivid sensory experiences) from “ideas” (faint copies of impressions). All ideas ultimately derive from impressions. There are no innate ideas—the mind starts as a blank slate.
“When we entertain any suspicion that a philosophical term is employed without any meaning or idea, we need but enquire, from what impression is that supposed idea derived?”
This becomes a powerful tool for critiquing metaphysical concepts that lack experiential basis.
The Problem of Causation
Hume’s analysis of causation is revolutionary. When we see one billiard ball strike another, we observe only succession and contiguity—one event followed by another. We never observe the “necessary connection” that would make the second event inevitable.
Our belief in causation rests on custom and habit, not reason. We expect the future to resemble the past, but this expectation cannot be rationally justified.
Miracles and Religion
Hume argues that testimony can never establish a miracle. By definition, miracles violate natural laws established by uniform experience. Any testimony is less reliable than our experience of nature’s regularity.
The Limits of Reason
The Enquiry shows that much of what we take for knowledge rests on psychological habits rather than rational justification. Yet Hume is not a nihilist—he accepts that we must rely on custom in practical life.
This tension between philosophical skepticism and natural belief remains central to epistemology.