A Treatise of Human Nature is a philosophical text by the Scottish philosopher David Hume. The work contains three books: "Of the Understanding", "Of the Passions" and "Of Morals". Written by Hume when he was 26, it is considered by many to be Hume's best work and one of the most important books in philosophy's history.

David Hume (7 May 1711 – 25 August 1776) was a Scottish philosopher, historian, economist, and essayist, who is best known today for his highly influential system of philosophical empiricism, skepticism, and naturalism. Hume's empiricist approach to philosophy places him with John Locke, Francis Bacon and Thomas Hobbes as a British Empiricist. Beginning with his A Treatise of Human Nature (1739), Hume strove to create a total naturalistic science of man that examined the psychological basis of human nature. Against philosophical rationalists, Hume held that passion rather than reason governs human behaviour. Hume argued against the existence of innate ideas, positing that all human knowledge is founded solely in experience; Hume thus held that genuine knowledge must either be directly traceable to objects perceived in experience, or result from abstract reasoning about relations between ideas which are derived from experience, calling the rest "nothing but sophistry and illusion", a dichotomy later given the name Hume's fork.

In what is sometimes referred to as Hume's problem of induction, he argued that inductive reasoning and belief in causality cannot be justified rationally; instead, our trust in causality and induction result from custom and mental habit, and are attributable only to the experience of "constant conjunction" of events. This is because we can never actually perceive that one event causes another, but only that the two are always conjoined. Accordingly, to draw any causal inferences from past experience it is necessary to presuppose that the future will resemble the past, a presupposition which cannot itself be grounded in prior experience.