February 19: Logically Speaking

Ruth Bacan Marcus, a groundbreaking logician and professor of philosopher at Yale University, died at 90 on this date in 2012. She came to prominence with a 1946 article in The Journal of Symbolic Logic in which she proposed a formula for positing a connection between possibility and actuality. Her Barcan formula translates into words as saying: “If everything is necessarily F, then it is necessary that everything is F” -- which Oxford professor of logic Timothy Williamson sums up as meaning, “If there can be something that has a certain property, then there is something that can have that property.” Writes Margalit Fox in the New York Times: “Because of its affinities with mathematics and the hard sciences — disciplines historically unwelcoming to women — logic had long been one of philosophy’s most swaggering strains. For a woman of Professor Marcus’s generation to elbow her way into the field, then dominated by titans like Willard Van Orman Quine, Rudolf Carnap and Kurt Gödel, was almost unheard of.” Marcus was the daughter of socialists, her father a typesetter and writer for the Yiddish Forward. She was also a champion fencer, and active in political protest against the Vietnam War. For the 2001 Yale commencement, she refused to sit in her customary place onstage to protest President George W. Bush’s receiving an honorary degree. “Following her noteworthy debut on the academic stage, Marcus went on to write seminal papers on essentialism, epistemology, belief, language, and ethics. Her major contribution in the last category was her work on moral dilemmas — i.e., cases in which one has an obligation to do x and an obligation to do y, even though it is not possible to do both x and y. She rejected the then-prevailing view that any moral code that does not rule out the possibility of moral dilemmas is thereby inconsistent. A much-acclaimed collection of her essays, Modalities, was published in 1993.” — Yale News