David Hume
1711 CE – 1776 CE · Enlightenment Era
“All knowledge derives from experience; reason alone cannot establish matters of fact.”
Biography
David Hume was a Scottish philosopher, historian, and essayist whose cheerful temperament belied the force of his philosophical arguments. Born in Edinburgh, he conceived his philosophical masterwork, A Treatise of Human Nature, while still in his early twenties during a period of intense study in France, and was bitterly disappointed when it 'fell dead-born from the press,' attracting almost no attention. He rewrote his ideas in more accessible form as the Enquiries, which fared better, but his real fame in his own lifetime came from his six-volume History of England and his elegant literary essays. His philosophical reputation, however, grew enormously after his death. Hume pushed empiricism, the doctrine that all knowledge comes from experience, to its logical conclusions with results so bold that they shook the foundations of science, morality, and religion. Kant credited Hume with awakening him from his 'dogmatic slumber,' and virtually every major epistemological debate since has been, in some sense, a response to Hume's challenges.
Major Works
Key Arguments
Click “Philosophy 101” to read the full exploration of each argument.
The Problem of Induction
Every day the sun has risen. Every time we have dropped a stone, it has fallen. But can we rationally justify our belief that the sun will rise tomorrow, or that the next stone will fall? Hume argued that we cannot. Our confidence in the regularity of nature rests on the assumption that the future will resemble the past, but that assumption is itself based on past experience (the future has always resembled the past before), which means we are reasoning in a circle. We cannot prove the uniformity of nature by appealing to experience, because the reliability of experience is precisely what is in question. Hume concluded that our belief in causation and natural regularity is not grounded in reason at all but in custom and habit, the mind's tendency to expect familiar patterns to continue. This does not mean we should stop trusting experience, we cannot help ourselves, but it means that the foundation of empirical knowledge is psychological rather than logical.
Why it matters: Still unsolved. It challenges the rational basis of scientific reasoning itself, and every proposed solution, from Kant's synthetic a priori to Popper's falsificationism to Bayesian probability, is still debated.
The Is-Ought Problem
Hume noticed something peculiar about moral reasoning: writers on ethics constantly begin with factual observations about human nature or God's commands, and then suddenly shift, without justification, to conclusions about what people ought to do. But there is a logical gap between 'is' and 'ought', between descriptions of how things are and prescriptions about how they should be. From the fact that humans naturally seek pleasure, it does not logically follow that they ought to seek pleasure. From the fact that God commands something, it does not logically follow (without additional premises) that we ought to obey. Hume argued that moral judgments are not discoveries of reason but expressions of sentiment, we call things 'virtuous' because they produce a feeling of approval in us, not because reason has detected some moral property in the world. Reason can inform us about facts and consequences, but the ultimate source of moral judgment is feeling.
Why it matters: Fundamental to metaethics and the fact-value distinction. Hume's challenge forced every subsequent moral philosopher to explain how moral claims can be justified, and his sentimentalist approach to ethics has experienced a major revival in contemporary moral psychology.
Critique of Causation
We believe that causes necessarily produce their effects, that fire necessarily causes heat, that billiard balls necessarily move when struck. Hume argued that this belief, despite feeling absolutely certain, has no rational basis. When we observe one billiard ball striking another, what do we actually see? We see one ball move, contact the other, and the second ball move. We see sequence and contiguity, one event followed by another, but we never observe the 'necessary connection' between them. We never see the power or force by which one event produces another. Our idea of necessary causation comes not from observing the world but from the mind's habit of associating events that have regularly occurred together. After seeing flame followed by heat many times, the mind automatically expects heat when it sees flame, but this expectation is a psychological habit, not a rational insight into the nature of reality.
Why it matters: Undermined the metaphysical foundations of science (which depends on causal reasoning), provoked Kant's entire critical philosophy as a response, and paralleled Al-Ghazali's similar critique of causation, made six centuries earlier from a theological direction, by arriving at comparable conclusions through secular empiricism.
Lasting Influence
Awakened Kant from his 'dogmatic slumber.' Influenced positivism, cognitive science, and remains central to epistemology.
Your Reading Path
The Companion Guide
Seven eras of philosophy in one volume — reading lists, key terms, journal prompts · $19.99