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Impressed by Isaac Newton's success at explaining the apparently diverse and chaotic physical world with a few universal principles, David Hume (1711-1776), while still in his teens, proposed that the same might be done for the realm of the mind. Through observation and experimentation, Hume hoped to uncover the mind's "secret springs and principles." Hume's proposal for a science of the mind was published as A Treatise of Human Nature in 1740, and subtitled "An Attempt to introduce the experimental Method of Reasoning into moral subjects." Though it is now one of the most widely read works in Western philosophy, the reception of the Treatise in Hume's lifetime was disappointing. In My Own Life Hume says that the Treatise "fell dead-born from the press." Considered an atheist by the clergy, which controlled university appointments, Hume sought but never received a professorship.
Hume is widely regarded as belonging with Locke and Berkeley to the philosophical movement called British Empiricism (see RATIONALISM VS. EMPIRICISM). The mind contains two kinds of perceptions: impressions and ideas. Impressions are the original lively SENSATIONS and EMOTIONS. Ideas are fainter copies of impressions. Like Locke, Hume rejected the NATIVISM of the rationalists. There are no ideas without prior impressions, so no ideas are innate. Impressions and ideas may be simple or complex. The imagination freely concatenates perceptions; the understanding and the passions organize perceptions by more regular rules of association. MEMORY ideas, for example, preserve the order and position of the impressions from which they derive. Hume's theory of ideas is an empiricist account of concept formation (see CONCEPTS).
Hume held that the ability to form beliefs, in contrast to having sensations and emotions, was a matter of inference. The belief that bread nourishes is an inference from the constant conjunction of the ingestion of bread with nourishment. In what is now called the problem of INDUCTION, Hume argued that this inference is not a deductive inference, because the proof of the conclusion is not guaranteed by the truth of the premises, and any proof based on experience is itself an inductive inference, making it thus a circular proof. Hume's conclusion is a skeptical one. There is no rational justification for CAUSAL REASONING.
Causal inference leading to belief is a matter of custom and habit. The constant conjunction of perceptions experienced lead cognitive agents to have certain lively ideas or beliefs. One cannot help but believe that fire is hot. Hume emphasized that both humans and other animals make such inductive or causal inferences to predict and explain the world, in spite of the fact that such inferences cannot be rationally justified. In the section of the Treatise entitled "Of the reason of animals," Hume anticipated COGNITIVE ETHOLOGY by appealing to evidence about nonhuman animals in support of the claim that inferences from past instances are made by members of many species. The possession of language by humans, Hume held, makes it possible for humans to make more precise inferences than other animals, but this is a matter of degree, not of kind.
If beliefs are habitual responses to environmental regularities, how is it that beliefs that deny such regularities are held? Hume's critical examination of religious belief and the belief in the existence of miracles inspired him to offer a fuller account of the nature of belief formation and credulity. Hume noted several belief-enlivening associative me chanisms in addition to constant conjunction. Belief is influenced by such factors as proximity, resemblance, and repetition. A pilgrimage to the Red Sea, for example, will serve to make one more receptive to the claim that the sea parted. Hume's treatment of the factors influencing belief anticipates the studies of Kahneman and TVERSKY (Tversky and Kahneman 1974) on the selective availability of evidence in PROBABILISTIC REASONING.
Hume rejected DESCARTES's claim that the mind is a mental substance on the grounds that there is no impression from which such an idea of mental substance could be derived. Introspection provides access to the mind's perceptions, but not to anything in which those perceptions inhere. "When I enter most intimately into what I call myself, I always stumble on some particular perception or other, of heat or cold, light or shade, love or hatred, pain or pleasure. I never can catch myself at any time without a perception, and never can observe any thing but the perception" (Treatise, p. 252). The mind, Hume concludes, "is nothing but a heap or collection of different perceptions."
The bundle theory of the mind has been criticized by recent philosophers of mind. Hume attempted to account for mental representation by the dynamic interaction of mental items -- impressions and ideas. It is not clear that Hume was able to characterize such interaction as mental without appealing to the fact that impressions and ideas are the perceptions of a mind. According to Hume's critics, Hume helps himself to the concept of mind rather than account for it in nonmentalistic terms. Dennett (1978) refers to this as Hume's Problem. Haugeland (1984) argues that such mechanistic accounts of the mind, which predate the notion of automatic symbol manipulation, cannot avoid Hume's problem.
The perceptions of the mind include emotions and passions as well as beliefs, and Hume attempted to offer a unified account of all mental operations. Beliefs are lively or vivacious ideas that result from a certain kind of mental preparation, a constant conjunction of pairs of impressions such as impressions of flame joined with impressions of heat. The lively idea of heat gets its vivacity from the habit or custom formed by the experience of the constantly conjoined impression pair. Beliefs, then, are themselves feelings. Both emotions and beliefs are strongly held perceptions, and the mechanisms that actuate one can influence the other. Fear of falling from a precipice may, for example, displace a belief that one is secure. Like recent theorists, Hume held that both probability and the degree of the severity of anticipated pain or pleasure play a role in the resolution of conflicts of emotion and judgment.
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Copyright © 1999 Massachusetts Institute of Technology