slippery slope argument an argument that an action apparently unobjectionable in itself would set in motion a train of events leading ultimately to an undesirable outcome. The metaphor portrays one on the edge of a slippery slope, where taking the first step down will inevitably cause sliding to the bottom. For example, it is sometimes argued that voluntary euthanasia should not be legalized because this will lead to killing unwanted people, e.g. the handicapped or elderly, against their will. In some versions the argument aims to show that one should intervene to stop an ongoing train of events; e.g., it has been argued that suppressing a Communist revolution in one country was necessary to prevent the spread of Communism throughout a whole region via the so-called domino effect. Slippery slope arguments with dubious causal assumptions are often classed as fallacies under the general heading of the fallacy of the false cause. This argument is also sometimes called the wedge argument. There is some disagreement concerning the breadth of the category of slippery slope arguments. Some would restrict the term to arguments with evaluative conclusions, while others construe it more broadly so as to include other sorites arguments. See also SORITES PARADOX , VAGUENES. W.T. Smart, J(ohn) J(amieson) C(arswell) (b.1920), British-born Australian philosopher whose name is associated with three doctrines in particular: the mind–body identity theory, scientific realism, and utilitarianism. A student of Ryle’s at Oxford, he rejected logical behaviorism in favor of what came to be known as Australian materialism. This is the view that mental processes – and, as Armstrong brought Smart to see, mental states – cannot be explained simply in terms of behavioristic dispositions. In order to make good sense of how the ordinary person talks of them we have to see them as brain processes – and states – under other names. Smart developed this identity theory of mind and brain, under the stimulus of his colleague, U. T. Place, in ‘Sensations and Brain Processes’ (Philosophical Review, 1959). It became a mainstay of twentieth-century philosophy. Smart endorsed the materialist analysis of mind on the grounds that it gave a simple picture that was consistent with the findings of science. He took a realist view of the claims of science, rejecting phenomenalism, instrumentalism, and the like, and he argued that commonsense beliefs should be maintained only so far as they are plausible in the light of total science. Philosophy and Scientific Realism (1963) gave forceful expression to this physicalist picture of the world, as did some later works. He attracted attention in particular for his argument that if we take science seriously then we have to endorse the four-dimensional picture of the universe and recognize as an illusion the experience of the passing of time. He published a number of defenses of utilitarianism, the best known being his contribution to J. J. C. Smart and Bernard Williams, Utilitarianism, For and Against (1973). He gave new life to act utilitarianism at a time when utilitarians were few and most were attached to rule utilitarianism or other restricted forms of the doctrine. See also PHILOSOPHY OF MIND, SCIENTIFIC REALISM , UTILITARIANIS. P.P.