David Hume

A Treatise of Human Nature

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A Treatise of Human Nature Summary

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A Treatise of Human Nature (1738) is the most comprehensive work published by the Scottish philosopher David Hume, widely regarded as the most influential English-language philosopher and one of the most important figures in philosophical history. The Treatise aims to place the study of human nature on the same empirical footing which Hume’s contemporary Isaac Newton brought to the physical sciences. Contrary to the philosophical rationalists of his day, Hume argues that emotion and mental habit, rather than reason, form the basis of most human beliefs. By examining his own inner landscape, and deploying skeptical reasoning about what he finds there, Hume concludes that there is no rational basis for any belief in morality, cause-and-effect, or personal identity. As well as making an essential contribution to the philosophical doctrines of empiricism, skepticism, and naturalism, A Treatise of Human Nature has been extremely influential in the fields of psychology and cognitive science.

Hume introduces the Treatise by setting out his proposal to bring an empirical methodology to the study of the human mind. He argues that without a scientific understanding of human thought itself, the other sciences, and all other intellectual disciplines including philosophy, are built on unknown and uncertain foundations. Since controlled experimentation is impossible where mental processes are concerned, Hume proposes to base his “science” on his own mind and the behavior of people around him.

The first of the Treatise’s three books is “Of the Understanding,” in which Hume attempts to set out “the extent and force of human understanding.” In Parts I & II of this book, Hume takes aim at the rationalist belief in innate ideas which derive from the intellect alone. He argues that all ideas derive ultimately from sensory impressions. Complex ideas are collections of simple ones. Abstract ideas, he suggests, are formed from sense impressions by a particular habit of mind. This applies even to such abstractions as space, time, and existence.

In Part III, Hume classifies the types of possible knowledge. He argues that in addition to knowledge gained directly from sensory experience, there is also knowledge which arises from the relations between our ideas, such as the intuitive knowledge that one color is brighter than another, and the knowledge that can be demonstrated by mathematical reasoning. Noting that we are also able to achieve knowledge inductively—that is, by observing the constant relationship between a cause and its effect—he asks where our idea of causation comes from. He concludes that our belief in cause and effect is a product of the mind’s natural habit of associating ideas which have appeared together in the past.

Part IV considers the philosophical position of skepticism: the belief that no certain knowledge is possible. Hume concludes that this position is simply irrefutable, but that the horror of skepticism can easily be overcome by “carelessness and inattention.” He advances skeptical critiques of arguments for the existence of an external world, the mind and personal identity, arguing that all these ideas derive from natural habits of the mind. Hume concludes the book by subjecting even his skepticism to skeptical doubt, suggesting that the habit of philosophical inquiry is just that: a habit.

Book II, “Of the Passions,” begins by classifying types of human emotion, analyzing how emotion arises in the mind and attaches itself to particular ideas. He tests his account by examining examples of pride, humility, love, hatred, and “compound passions” (made up of one or more simple emotions). Throughout, he argues that identical processes can be observed in animals as well as humans.

Part III of the second book discusses the question of free will. He argues that other than by violent restraint or compulsion, which can restrain our freedom, human beings’ actions are completely determined. Our belief that we could have acted differently than we did derives from the vague, imaginary idea we can conjure of our alternative course. From there, Hume goes on to examine the mental causes that determine our actions.

Book III, “Of Morals,” sets out Hume’s argument that moral judgment derives from mental impressions—emotions that attach to particular ideas—rather than rational distinctions. He argues that reason is useless in moral argument, concluding famously that the way things “ought” to be can never be deduced from the way things “are.” Part II considers justice and injustice, arguing that they are “artificial virtues” created by social convention. He goes on to attempt a historical analysis of how these conventions came into existence. He develops this analysis to account for the existence of laws, governments, and patriarchal conventions governing women’s behavior.

Finally, Hume turns to the “natural virtues,” arguing that our ideas of such virtues as courage and benevolence ultimately derive from sympathy and an innate preference for what is useful to us and to society. He concludes by reassuring readers that his system need not undermine our sense of the value of morals.

When the Treatise was received poorly by contemporary readers, Hume substantially reworked it into two volumes, An Enquiry Concerning Human Understanding (1748) and An Enquiry Concerning the Principles of Morals (1751). However, the Treatise’s reputation has grown with Hume’s, and it is now regarded by many as the most important philosophical work written in English.