Where does knowledge come from? Empiricists say experience. The mind starts as a blank slate, and the senses fill it. John Locke argued that all ideas trace back to sensation and reflection. George Berkeley pushed further, denying matter altogether and reducing reality to perceptions. David Hume systematized empiricism, arguing that causation, substance, and the self are not given in experience but constructed by habit and imagination. The tradition contrasts with rationalism, which holds that reason can grasp truths independent of experience.

Empiricism shaped modern science. Francis Bacon argued for observation and experiment over speculation. The logical positivists of the early 20th century tried to ground all meaningful statements in empirical verification. That program collapsed under its own weight, since the verification principle itself is not empirically verifiable. Empiricism also faces the problem of induction, which Hume raised: no amount of observed regularity guarantees the next case. The sun has risen every day, but that does not prove it will rise tomorrow. Empiricists have responded with various accounts of probability, inference, and scientific method, but the problem remains unresolved.

Empiricist themes

• Experience. The senses are the source of knowledge.
• Blank slate. The mind begins empty.
• Induction. General knowledge comes from particular observations.
• Verification. Claims must be testable by experience.

Empiricism is not the same as science, but it is the philosophy that most closely informs scientific practice.