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Sidgwick, Henry (1838-1900)

English moral and political philosopher. In The Methods of Ethics (1874) and Outlines of the History of Ethics (1886), Sidgwick surveyed the varieties of argument that may be applied to moral judgments, including intuitive common-sense, calculation of self-interest, and a utilitarian normative theory. He supposed that although each is well-founded, the three cannot be wholly reconciled with each other. We are therefore perpetually vulnerable to the possibility of conflicting moral obligations.

Recommended Reading: The Works of Henry Sidgwick, ed. by John Slater (Thoemmes, 1997); Henry Sidgwick, Essays on Ethics and Method, ed. by Marcus G. Singer (Oxford, 2001); Henry Sidgwick, Philosophy: Its Scope and Relations (St. Augustine, 1998); Henry Sidgwick, ed. by Ross Harrison (Oxford, 2001); J. B. Schneewind, Sidgwick's Ethics and Victorian Moral Philosphy (Oxford, 1977); and Essays on Henry Sidgwick, ed. by Bart Schultz (Cambridge, 1992).

Also see SEP, EB, and Soshichi Uchii.

Siger of Brabant (1235-1282)

French philosopher. As one of the radical Aristoteleans in Paris, Siger endorsed the philosophy of Ibn Rushd and rejected medieval preoccupation with theological concerns in his Quaestiones in Metaphysicam (Metaphysical Questions). Suspected of pursuing a "double truth," Siger became one of the chief targets of the Condemnation of 1270.

Recommended Reading: Tony Dodd, The Life and Thought of Siger of Brabant (Edwin Mellen, 1998).

Also see EB.


Latin for "simply" or "naturally" (in contrast with secundum quid). Hence, what anything is when considered absolutely or without qualification.

Simplification (Simp.)

A rule of inference of the form:

	p • q


Example: "Jevona is tall and Jevona is thin. Therefore, Jevona is tall."

Although trivial in ordinary language, this pattern of reasoning is vital for proof construction in the propositional calculus.

sine qua non

Latin for "without which, not;" hence, an alternative way of expressing the presence of a necessary condition.

Singer, Peter (1946- )

Australian philosopher. Singer is an ethicist whose Practical Ethics (1979) emphasizes the application of consequentialist moral principles to matters of personal and social concern. He is most widely admired for Animal Liberation (1975), in which Singer shows that, since a difference of species entails no moral distinction between sentient beings, it is wrong to mistreat non-human animals; it follows that animal experimentation and the eating of animal flesh are morally indefensible. In "Do Animals Feel Pain?, Singer argues for the moral relevance of animal pain.

Recommended Reading: Peter Singer, How Are We to Live?: Ethics in an Age of Self-Interest (Prometheus, 1995); Peter Singer, Rethinking Life & Death: The Collapse of Our Traditional Ethics (St. Martin's 1996); Peter Singer, Ethics Into Action (Rowman & Littlefield, 1998); Peter Singer, Writings on an Ethical Life (Ecco, 2000); and Singer and His Critics, ed. by Dale Jamieson (Blackwell, 1999).

Also see EB.

singular proposition

A statement that some individual has a particular feature. In categorical logic, since its subject term designates a unit class, the singular proposition should be interpreted as the conjuction of corresponding universal and particular propositions (either as A and I or as E and O).

Recommended Reading: Krista Lawlor, New Thoughts about Old Things: Cognitive Policies as the Ground of Singular Concepts (Garland, 2001).

Also see SEP on singular terms and singular propositions.

Sinn / Bedeutung

Frege's German distinction between the sense and reference of a term, intended to account for the possibility of genuinely informative statements of identity.


Belief that some or all human knowledge is impossible. Since even our best methods for learning about the world sometimes fall short of perfect certainty, skeptics argue, it is better to suspend belief than to rely on the dubitable products of reason. Classical skeptics include Pyrrho and Sextus Empiricus. In the modern era, Montaigne, Bayle, and Hume all advocated some form of skeptical philosophy. Fallibilism is a more moderate response to the lack of certainty.

Recommended Reading: Skepticism: A Contemporary Reader, ed. by Keith Derose and Ted A. Warfield (Oxford, 1998); Skepticism, ed. by Ernest Sosa an, Enrique Villanueva (Blackwell, 2000); Richard Henry Popkin, The History of Skepticism from Erasmus to Spinoza (California, 1979); Barry Stroud, The Significance of Philosophical Skepticism (Clarendon, 1984); Ross Harrison, Hobbes, Locke, and Confusion's Masterpiece: An Examination of Seventeenth Century Philosophy (Cambridge, 2002); Robert C. Solomon, Spirituality for the Skeptic: The Thoughtful Love of Life (Oxford, 2002); Michael Huemer, Skepticism and the Veil of Perception (Rowman and Littlefield, 2001); Panayot Butchvarov, Skepticism in Ethics (Indiana, 1989); and Skepticism, ed. by Michael Williams (Dartmouth, 1993).

Also see IEP articles on ancient skepticism, a target="new" href="">modern skepticism, and contemporary skepticism, SEP on skepticism, ancient skepticism, medieval skepticism, and moral skepticism, Peter Suber, EB, Danilo Marcondes de Souza Filho, DPM, CE, and ISM.

Skinner, Burrhus Frederic (1904-1990)

American psychologist; author of Science and Human Behavior (1953) and Verbal Behavior (1957). Expanding on the behaviorist theories of Watson, Skinner engaged in strict scientific study of human behavior and proposed the application of psychology to the deliberate engineering of human societies. Skinner's Two Types of Conditioned Reflex (1935) provided a technical description of the ways in which animals acquire novel patterns of behavior. Walden 2 (1948) proposed the systematic use of psychological conditioning in pursuit of an improved society. Skinner rejected the notion of moral autonomy more generally in Beyond Freedom and Dignity (1971). In The Origins of Cognitive Thought (1989) Skinner offered a behaviourist explanation for human thinking.

Recommended Reading: B. F. Skinner, About Behaviorism (Random House, 1976); William T. O'Donohue and Kyle E. Ferguson, The Psychology of B. F. Skinner (Sage, 2001); Modern Perspectives on B. F. Skinner and Contemporary Behaviorism, ed. by James T. Todd and Edward K. Morris (Greenwood, 1995); and Robert D. Nye, The Legacy of B. F. Skinner: Concepts and Perspectives, Controversies and Misunderstandings (Wadsworth, 1992).

Also see EB and C. George Boeree.

Smart, John Jamieson Carswell (1920- )

English-Australian philosopher. Influenced by the methods of Ryle, Smart defends a strictly physicalist philosophy of mind in Philosophy and Scientific Realism (1963). Smart's noncognitivist approach to morality yields a defence of act utilitarianism in Utilitarianism: For and Against (1973), co-authored with Bernard Williams.

Recommended Reading: J. J. C. Smart and J. J. Haldane, Atheism and Theism (Blackwell, 1996).

Smith, Adam (1723-1790)

Scottish philosopher and economist. Smith modified the moral sense theory in his Theory of Moral Sentiments (1759), placing greater emphasis than had Hutcheson on the sentiment of sympathy and the virtue of self-control. Smith's An Inquiry into the Nature and Causes of the Wealth of Nations (1776) proposed the economic theory that social goods are maximized when individual human beings are permitted to pursue their own interests, restricted only by the most general principles of justice.

Recommended Reading: Jack Russell Weinstein, On Adam Smith (Wadsworth, 2000); Three Great Economists: Smith, Malthus, Keynes, ed. by D. D. Raphael, Donald Winch, Robert Skidelsky, and Keith Thomas (Oxford, 1997); James R. Otteson, Adam Smith's Marketplace of Life (Cambridge, 2002); Charles L. Griswold, Jr., Adam Smith and the Virtues of Enlightenment (Cambridge, 1998); and Jerry Z. Muller, Adam Smith in His Time and Ours (Princeton, 1995).

Also see EB and ELC.


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