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Any abstract notion or idea by virtue of which we apply general terms to things.

Recommended Reading: Christopher Peacocke, A Study of Concepts (Bradford, 1995).

Also see SEP, EB, and DPM.


Solution to the problem of universals. According to Abelard, general terms are applied to individual things by reference to abstract ideas or concepts.

Recommended Reading: David Wiggins, Sameness and Substance Renewed (Cambridge, 2001).

Also see EB and ISM.


A proposition whose truth has been inferred on the basis of other propositions assembled with it in a logical argument.

Also see EB.

Concomitant Variation, Method of

One of Mill's Methods. If an antecedent circumstance is observed to change proportionally with the occurrence of a phenomenon, it is probably the cause of that phenomenon.

Example: "The more coffee I drink, the more difficult it is to fall asleep at night. Therefore, drinking coffee may be a cause of my insomnia."

Recommended Reading: John Stuart Mill, System of Logic (Classworks, 1986).

Condillac, Étienne Bonnot de (1715-1780)

French philosopher and clergyman; author of Logique (Logic) (1741), Essai sur l'origine des connaissances humaines (Essay on the Origin of Human Knowledge) (1746), Traité des systèmes (Treatise on Systems) (1749), Traité des sensations (Treatise on Sense Perception) (1754), Traité des animaux (Treatise on Animals) (1755), and Langue des calculs (The Language of Numbers) (1777). As one of the Encyclopedists, Condillac was the foremost French popularizer of the empiricist philosophy of Locke.

Recommended Reading: Philosophical Writings of Etienne Bonnot, Abbe De Condillac, ed. by Franklin Phillip (Erlbaum, 1987) and Jacques Derrida, The Archeology of the Frivolous: Reading Condillac, tr. by John P. Leavey (Nebraska, 1987).

Also see SEP, EB, Alfred Weber, ELC, WSB, and CE.


Any statement of the form: "If (antecedent), then (consequent)." Although conditionals may have several uses in ordinary language, all share at least the truth-functional structure of material implication.

Recommended Reading: Anthony Appiah, Assertion and Conditionals (Cambridge, 1985); Nelson Goodman, Fact, Fiction, and Forecast (Harvard, 1983); Frank Jackson, Conditionals (Oxford, 1991); H. McLaughlin, On the Logic of Ordinary Conditionals (SUNY, 1990); and Michael Woods, Conditionals, ed. by David Wiggins and Dorothy Edgington (Clarendon, 1997).

Also see SEP and EB.


The relationship between empirical evidence and the scientific hypotheses it is used to support. Although abductive reasoning can provide only partial or incomplete support for such hypotheses, their falsification by contadictory evidence can be absolute. Hempel pointed out a systematic paradox regarding the nature of confirming instances.

Recommended Reading: Karl R. Popper, Logic of Scientific Discovery (Routledge, 1992); Richard Swinburne, An Introduction to Confirmation Theory (Methuen, 1973); Lawrence Sklar, Probability and Confirmation (Garland, 1999); and Induction, Probability, and Confirmation, ed. by Maxwell Grover and Robert Anderson.

Also see Michael Huemer and SEP.

 p  q  p • q 

A compound statement that is true just whenever both of its component statements (the conjuncts) are true. Conjunctions are symbolized here in the form:

	p • q

Example: "Jennie is tall and Salaam is thin.".

Conjunction (Conj.)

A rule of inference of the form:



	p • q

Example: "Kay has a doctorate. Alan has a doctorate. Therefore, both Kay and Alan have doctorates."

Although obvious in ordinary language, this pattern of reasoning must be formally justified in the propositional calculus.

Also see EB.


A logical symbol used to make compound statements out of simpler component statements. The truth-functional connectives used here include:

~      for negation,
•      for conjunction,
∨      for disjunction,
⊃     for implication, and
      for equivalence.

Also see SEP and EB.


The associative meaning of a term, including especially those features in virtue of which the term is properly applied; see denotation / connotation.

Recommended Reading: Beatriz Garza-Cuaron, Connotation & Meaning (De Gruyter, 1991).

Also see EB.


Inner awareness of the difference between right and wrong in one's own actions, usually understood as a divinely-inspired moral sense. Although Aquinas noted that an individual conscience may err, Butler held that it is the fundamental motive for good conduct.

Recommended Reading: Joseph Butler, Fifteen Sermons on Human Nature (Classworks, 1986) and James Q. Wilson, The Moral Sense (Simon & Schuster, 1997).

Also see SEP, EB, IEP, and Steven Darwall.

consciousness {Ger. Bewußtsein}

The subjective phenomenon of self-awareness that normally accompanies human experience. Correct analysis of consciousness is a central goal in the philosophy of mind.

Recommended Reading: William Seager, Theories of Consciousness (Routledge, 1999); Daniel C. Dennett, Consciousness Explained (Little, Brown, 1992); William G. Lycan, Consciousness (Bradford, 1995); Joseph S. Catalano, Thinking Matter: Consciousness from Aristotle to Putnam and Sartre (Routledge, 2000); Mark Rowlands, The Nature of Consciousness (Cambridge, 2001); M.R. Bennett and P.M.S. Hacker, Philosophical Foundations of Neuroscience (Blackwell, 2003); David J. Chalmers, The Conscious Mind: In Search of a Fundamental Theory (Oxford, 1997); and The Nature of Consciousness: Philosophical Debates, ed. by Ned Block and Owen Flanagan (MIT, 1997).

Also see Eric Lormand, John Searle, David J. Chalmers, EB, SEP on consciousness, seventeenth-century views, the unity of consciousness, consciousness and intentionality, representational theories, higher-order theories, temporal consciousness, animal consciousness, and the language of thought, DPM, Ralph Ellis, and CE.


The element of a conditional statement that states its outcome or result. For example, "You'll see me tomorrow" is the consequent of both:

"If you come by the office, then you'll see me tomorrow." and

"You'll see me tomorrow, unless I see you first.".


Any normative theory holding that human actions derive their moral worth solely from the outcomes or results that they produce. Utilitarianism is a consequentialist theory that typically identifies happiness or pleasure as the favored consequence. One of the difficulties inherent in the practical application of any such theory is our notoriously feeble ability (or willingness) to predict accurately what consequences our own actions will produce.

Recommended Reading: Consequentialism, ed. by Philip Pettit (Dartmouth, 1993); Anthony Quinton, Utilitarian Ethics (Open Court, 1989); Brad Hooker, Ideal Code, Real World (Oxford, 2000); Tim Mulgan, The Demands of Consequentialism (Oxford, 2001); Samuel Scheffler, Consequentialism and Its Critics (Oxford, 1988); and Marcia Baron, Philip Pettit, and Michael Slote, Three Methods of Ethics - A Debate For and Against: Consequences, Maxims, and Virtues (Blackwell, 1997).

Also see IEP, EB, SEP, and ISM.


Feature of any formal system from whose axioms no direct contradiction follows. The customary proof of consistency is to show that there is at least one interpretation of the system upon which all of its axioms are true.

Recommended Reading: Richard C. Jeffrey, Formal Logic: Its Scope and Limits (McGraw-Hill, 1990).

Also see EB and SEP on paraconsistent logic and inconsistent mathematics.


In a system of formal logic, any symbol that—unlike a variable—specifically designates an item. Thus, the propositional calculus employs statement constants, while quantification theory makes use of both individual and predicate constants.

Constructive Dilemma (C.D.)

A rule of inference of the form:

	( p ⊃ q ) • ( r ⊃ s )

	p ∨ r

	q ∨ s

Example: "If it's sunny tomorrow we'll have a picnic, and if it rains we'll go bowling. But either it will be sunny or it will rain tomorrow. Therefore, either we'll have a picnic or we'll go bowling."

The reliability of this pattern of reasoning is established by a truth-table.

Also see EB.

continence / incontinence

Distinction between modes of human action in the ethics of Aristotle. A continent agent is able to carry out actions that conform to the demands of reason, while an incontinent agent is overcome by desire and said to suffer from weakness of the will.

Recommended Reading: Nichomachean Ethics, tr. by Terence Irwin (Hackett, 1985); Robert Dunn, The Possibility of Weakness of Will (Hackett, 1987); and Anthony Kenny, Aristotle's Theory of the Will (Yale, 1979).


The status of a proposition that could, depending upon the circumstances, be either true or false. See necessary / contingent. A compound statement in the propositional calculus is contingent if its truth depends upon that of its simpler components.


A logical falsehood. A statement which, by virtue of its form, cannot be used to make a true assertion.

For example: "Sugar is sweet and sugar is not sweet."

Recommended Reading: Aristotle & Lukasiewicz on the Principle of Contradiction, ed. by Frederick Seddon (Modern Logic, 1996).

Also see SEP and EB.


A pair of categorical propositions, each of which is true if and only if the other is false. In the traditional square of opposition, an A proposition and its corresponding O are contradictories, as are an E proposition and its corresponding I. Thus, for example:

All dogs are mammals and Some dogs are not mammals

are contradictories, as are

No fish are tuna and Some fish are tuna.

Also see EB.


The reciprocal relationship between two categorical propositions of the same form such that the subject term of each is the complement of the predicate term of the other. Contraposition is a valid immediate inference for both A and O propositions. Thus, for example:

All voters are citizens and All non-citizens are non-voters

Some ants are not biters and Some non-biters are not non-ants

are legitimate cases of contraposition.

Also see EB.


A pair of categorical propositions which (provided that we assume existential import) cannot both be true, but can both be false. In the traditional square of opposition, an A proposition and its corresponding E are contraries. Thus, for example:

All cars are green and No cars are green are contraries.

Also see EB.


Belief that judgments of a specific sort are grounded only on (explicit or implicit) agreements in human society, rather than by reference to external reality. Although this view is commonly held with respect to the rules of grammar and the principles of etiquette, its application to the propositions of law, ethics, science, mathematics, and logic is more controversial.

Recommended Reading: Alan Sidelle, Necessity, Essence, and Individuation: A Defense of Conventionalism (Cornell, 1989).

Also see SEP and EB.

converse accident {Lat. a dicto secundum quid ad dictum simpliciter}

The informal fallacy of using exceptional specific cases as the basis for a general rule, omitting reference to their qualifying features.

Example: "It rained on my birthday this year and it rained on my birthday last year. Therefore, it always rains on my birthday."

Also see FF and GLF.


The reciprocal relationship between two categorical propositions of the same form such that the subject term of each is the predicate term of the other. Conversion is a valid immediate inference for both E and I propositions. Thus, for example:

No snakes are mammals and No mammals are snakes, like

Some carnivors are birds and Some birds are carnivors

are each the converse of the other.

Also see EB.

converting the conditional

A fallacy of the form:

	p ⊃ q

	q ⊃ p

Example: "If Sally voted last year, then she is over 21. Therefore, if Sally is over 21, then she voted last year."

Reasoning of this sort should not be confused with legitimate instances of Transposition.

Also see FF.

Conway, Anne (Finch) (1631-1679)

English philosopher; author of Principia philosophiae antiquissimae et recentissimae de Deo, Christo & Creatura (The Principles of the Most Ancient and Modern Philosophy) (1690). A student of Henry More, she engaged in a lengthy correspondence with Leibniz, who borrowed her use of the term, "monad." Conway developed and defended a monistic system in which all beings are modes of god, the one and only spiritual substance.

Recommended Reading: The Conway Letters: The Correspondence of Anne, Viscountess Conway, Henry More, and Their Friends, 1642-1684, ed. by Marjorie Hope Nicolson (Clarendon, 1992) and Women Philosophers of the Early Modern Period, ed. by Margaret Atherton (Hackett, 1994).

Also see SEP, Bill Uzgalis, and ELC.


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