David Hume, a Scottish philosopher, was one of the most important figures in the history of philosophy. His thought marks the culmination of the British philosophical movement of the 1700's known as empiricism. The empiricists tried to show that all human thought and knowledge is based on the direct experience of the world through the senses. In order to show this, Hume and the other empiricists had to analyze the workings of the human mind.

Hume distinguished between impressions and ideas. Impressions are made on the mind when we directly experience anything. Ideas do not arise directly from experience, but are formed from previous impressions. For example, one's idea of a table or of a triangle is based on previous impressions and experiences of those things. We can form ideas of things we have never experienced, but only by combining previous experiences in new ways.

Hume applied this theory to philosophical questions, especially questions about the limits of knowledge. He maintained that since ideas must be based on experience, ideas without such basis lack a proper foundation. Hume argued that a number of ideas central to traditional philosophy are problematic in this way. These include the ideas of substance, the self, and causality.

The idea of substance is the idea of the stuff or matter of a thing, as opposed to its qualities. These qualities (for example, color, shape, smell, or taste) are considered to be qualities of something--that is, of the substance or matter. But we can experience only the qualities, and we never can experience the substance itself. Thus, the idea of substance has no meaning.

The idea of the self is the idea of something in a person that remains identical through time. I have the idea that I remain the same person despite the changes that occur in me. But, since I cannot locate in myself an element that is always present and never changes, the idea of such a self has no basis in experience.

The idea of causality is the idea that two events are connected in such a way that one causes the other. For example, it seems that one billiard ball rolling into another causes the second ball to move. Hume pointed out that, in such cases, we perceive only that events like the cause are regularly followed by events like the effect. The rolling of one ball into another is regularly followed by the second ball starting to move. But we never observe anything that actually connects the two events. But causes are supposed to connect events. Thus, the idea of causality, like the ideas of substance and self, has no basis in experience.

Hume argued that there are only two kinds of things about which we can know anything: matters of fact and relations of ideas. Statements about matters of fact are really descriptions of our experience of the world and ourselves. Statements about relations of ideas concern the truths of logic and mathematics and the definitions of words and ideas. They are supposedly discoverable by the operations of reason alone without reliance on sense experience. For example, we need not take a survey of bachelors to know that bachelors must be unmarried and male. This truth is discoverable solely on examination of the ideas involved. According to Hume, any statement is worthless that neither makes clear the meanings of ideas nor tells us anything about experience. Hume believed there were many such statements in traditional philosophy and theology. His aim was to expose long-accepted but unsound ideas.

In ethics, Hume argued that it is impossible to conclude from how things and people are anything about how they should be. He also believed that our basic choices are determined, not by reason, but by desires and passions that use reason as a tool to attain their goals. In religion, Hume criticized the argument that the world resembles a large and complex artifact--that is, something made by design and intention. Thus, it seems natural to conclude that it must have been made by a being capable of such a grand achievement, who could only be God. But Hume objected that it could have come into existence without any conscious plan or effort on the part of a God.

Hume was born and educated in Edinburgh. His first major work was A Treatise of Human Nature (1739). His other works include An Enquiry concerning Human Understanding (1748), An Enquiry concerning the Principles of Morals (1751), Dialogues concerning Natural Religion (1779), an influential history of Great Britain, and many essays.

SOURCE: IBM 1999 WORLD BOOK