Marcus, Ruth Barcan

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Ruth Barcan Marcus, though she has published in a number of areas, is best known for her groundbreaking papers in modal and philosophical logic. In 1946 she initiated the first systematic treatment of quantified modal logic (see Barcan, 1946), therein provoking W. V. Quine's decades-long attack upon the meaningfulness of quantification into alethic modal contexts. The ensuing dispute focused attention on the phenomenon of referential opacity and led to important developments in logic, metaphysics, and philosophy of language. In subsequent papers Marcus extended the first-order formalization to second order with identity (Barcan, 1947) and to modalized set theory (Marcus, 1963, 1974). Particularly significant theses presented in these works were the axiom (x)Fx (x)Fx, known as the Barcan formula (Barcan, 1946), and the proof of the necessity of identity (Barcan, 1947; Marcus, 1961). It is of some historical interest that Marcus introduced the now standard "box" operator for necessity.

Marcus's response to criticisms of quantified modal logic took many forms and was a theme to which she returned repeatedly throughout her career. In her 1961 paper (and elsewhere) she sought to dispel certain puzzles about substitutivity of identity in modal contexts; she was an early advocate of a substitutional interpretation of the quantifiers for certain purposes (Marcus, 1961, 1962, 1972), as for example in modal and fictional discourse; she maintained that quantification into modal contexts involves no commitment to an objectionable essentialism (Marcus, 1961), and she later developed and defended a version of Aristotelian essentialism within a modal framework (Marcus, 1967, 1976). Finally, in the mid-1980s she offered an explicit defense of the metaphysical actualism that had informed her early papers in modal logic (Marcus, 19851986). Here once again Marcus employed an objectual interpretation of the quantifiers, construing our core modal discourse as counterfactual discourse about actual objects.

Allied doctrines of enduring significance either originated or evolved in other writings by Marcus. For example, she introduced a flexible notion of extensionality whereby languages and theories are extensional to the extent that they identify relatively stronger equivalence relations with relatively weaker ones (Marcus, 1960, 1961). She also proposed that ordinary proper names are contentless directly referential tags (Marcus, 1961). In so doing, Marcus rejected earlier "descriptivist" accounts, often associated with Gottlob Frege and Bertrand Russell, and laid the cornerstone of the so-called new theory of direct reference later elaborated by Saul Kripke, Keith Donnellan, David Kaplan, and others.

Writing in moral theory, Marcus exposed defects in the structure of standard deontic logic (Marcus, 1966). She also argued that moral dilemmas are real and, moreover, that their reality is compatible with the consistency of the moral principles from which they derive (Marcus, 1980). Reasoning from a straightforward analogue of semantic consistency, she called into question familiar arguments from the existence of moral dilemmas to ethical antirealism. The resulting account also yielded some second-order principles of conflict avoidance.

Finally, in a series of papers on the nature of belief (Marcus, 1981, 1983, 1990), Marcus rejected language-centered theories according to which beliefs are attitudes to linguistic or quasilinguistic entities (sentences of English or "Mentalese," for instance). Her proposal was that an agent X believes that S if and only if X is disposed to respond as if S obtains, where S is a possible state of affairs and what is to count as such a response is a function of environmental factors and internal states such as X 's needs and desires. This object-centered theory, as opposed to the language-centered views of Donald Davidson and Jerry Fodor, for example, more naturally accommodates unconscious beliefs and beliefs of infralinguals and nonlinguals. It also accommodates a more robust notion of rationality and explains, as its rivals cannot, why a fully rational agent would not believe a contradiction. In the wide sense of the term, a rational agent is one who, among other things, strives to maintain the global coherence of the behavioralthat is, verbal as well as nonverbalindicators of his beliefs. Thus, although a rational agent might assent to a contradiction, his assent would not "go over" into a belief. Indeed, upon discovering the contradiction, he would retract his earlier (contradictory) belief claim. On Marcus's view, just as one cannot know what is false, one cannot believe what is impossible.

Marcus was professor of philosophy and chair of the department at the University of Illinois at Chicago from 1964 to 1970, professor of philosophy at Northwestern University from 1970 to 1973, and the Reuben Post Halleck Professor of Philosophy at Yale, where she succeeded her mentor Frederick B. Fitch, from 1973 to the time of her retirement in 1992. In addition to her scholarly achievements Marcus changed the face of the philosophical profession by her efforts on behalf of women. Perhaps most noteworthy in this connection was the reform of hiring practices instituted by the American Philosophical Association during her tenure as an officer and subsequently as chairman of its National Board of Officers.

See also Davidson, Donald; Fodor, Jerry A.; Frege, Gottlob; Kaplan, David; Kripke, Saul; Logic, History of; Metaethics; Metaphysics; Modal Logic; Philosophy of Language; Quine, Willard Van Orman; Rationality; Russell, Bertrand Arthur William; Set Theory.


works by marcus

Barcan, R. C. "A Functional Calculus of First Order Based on Strict Implication." Journal of Symbolic Logic 11 (1946): 116.

Barcan, R. C. "The Identity of Individuals in a Strict Functional Calculus of First Order." Journal of Symbolic Logic 12 (1947): 1215.

Marcus, R. B. "Extensionality." Mind 69 (273) (1960): 5562.

Marcus, R. B. "Modalities and Intensional Languages." Synthese 13 (1961): 303322.

Marcus, R. B. "Interpreting Quantification." Inquiry 5 (1962): 252259.

Marcus, R. B. "Classes and Attributes in Extended Modal Systems." Proceedings of the Colloquium in Modal and Many Valued Logic, Acta philosophica fennica 16 (1963): 123136.

Marcus, R. B. "Iterated Deontic Modalities." Mind 75 (300) (1966): 580582.

Marcus, R. B. "Essentialism in Modal Logic." Noûs 1 (1967): 9196.

Marcus, R. B. "Essential Attribution." Journal of Philosophy 67 (1971): 187202.

Marcus, R. B. "Quantification and Ontology." Noûs 6 (1972): 240250.

Marcus, R. B. "Classes, Collections, and Individuals." American Philosophical Quarterly 11 (1974): 227232.

Marcus, R. B. "Dispensing with Possibilia." Presidential address, Proceedings of the American Philosophical Association 49 (1976): 3951.

Marcus, R. B. "Moral Dilemmas and Consistency." Journal of Philosophy 77 (3) (1980): 121135.

Marcus, R. B. "A Proposed Solution to a Puzzle about Belief." In The Foundations of Analytic Philosophy, edited by P. French, T. Uehling, H. K. Wettstein. Midwest Studies in Philosophy 6. Minneapolis: University of Minnesota Press, 1981.

Marcus, R. B. "Rationality and Believing the Impossible." Journal of Philosophy 75 (1983): 321337.

Marcus, R. B. "Possibilia and Possible Worlds." Edited by R. Haller. Grazer philosophische Studien 2526 (19851986): 107132.

Marcus, R. B. "Some Revisionary Proposals about Belief and Believing." Philosophy and Phenomenological Research (Supplement 1990): 133154.

Marcus, R. B. Modalities. New York: Oxford University Press, 1993.

Diana Raffman (1996)

G. Schumm (1996)

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