Saul Kripke
Saul Aaron Kripke (born in
November,
1940,
Omaha,
Nebraska) is an
American philosopher and
logician now emeritus from
Princeton and professor of philosophy at
CUNY Graduate Center. He has been immensely influential in a number of fields related to
logic and
philosophy of language. Much of his work remains unpublished or exists only as tape-recordings and privately circulated manuscripts. Kripke was the winner of the 2001
Schock Prize in Logic and Philosophy.
Saul Kripke is the oldest of three children born to Dorothy and
Rabbi Myer Kripke. His father was the leader of Beth El Synagogue, the only Conservative congregation in Omaha. His mother wrote Jewish educational children's books. Saul and his two sisters, Madeline and Netta, attended
Dundee Grade School in Omaha and
Omaha Central High School. After graduating from high school in 1958, Kripke attended
Harvard University, earning a
bachelor's degree in
mathematics. During his sophmore year at Harvard, Kripke taught a graduate level logic course at nearby
MIT. Before becoming a professor at Princeton University, Kripke taught in the
philosophy department at
Rockefeller University in
New York City. Kripke married (and recently divorced)
Margaret Gilbert whose brother
Martin Gilbert is a well-known British historian. They have no children. He currently teaches courses in
Logic,
Metaphysics, and the
Philosophy of Language at the CUNY Graduate Center in midtown Manhattan.
Kripke is best known for four contributions to philosophy:
#
Kripke semantics for
modal and related logics, published in several essays beginning while he was still in his teens. # His 1970 Princeton lectures
Naming and Necessity (published in 1972 and 1980), that significantly restructured the
philosophy of language and, as some have put it, "made metaphysics respectable again". # His interpretation of the philosophy of
Wittgenstein.# His theory of
truth.
Two of Kripke's earlier works ("A Completeness Theorem in Modal Logic" and "Semantical Considerations on Modal Logic") were on the subject of
modal logic. The most familiar logics in the modal family are constructed from a weak logic called K, named after Kripke because of his contributions to modal logic.
In "Semantical Considerations on Modal Logic", published in
1963, Kripke responded to a difficulty with classical
quantification theory. The motivation for the world-relative approach was to represent the possibility that objects in one world may fail to exist in another. If standard quantifier rules are used, however, every term must refer to something that exists in all the possible worlds. This seems incompatible with our ordinary practice of using terms to refer to things that only exist contingently.
Kripke's response to this difficulty was to eliminate terms. He gave an example of a system that uses the world-relative interpretation and preserves the classical rules. However, the costs are severe. First, his language is artificially impoverished, and second, the rules for the propositional modal logic must be weakened.
Kripke's three lectures constitute an attack on the descriptivist (
Fregean,
Russellian) theory of reference with respect to
proper names, according to which a name refers to an object by virtue of the name's being associated with a description that the object in turn satisfies. He gave several examples purporting to render
descriptivism implausible (e.g., surely
Aristotle could have died at age two and so not satisfied any of the descriptions we associate with his name, and yet it would seem wrong to deny that he was Aristotle). As an alternative, Kripke adumbrated a
causal theory of reference, according to which a name refers to an object by virtue of a causal connection with the object as mediated through communities of speakers. In this way, a name is a
rigid designator: it refers to the named object in every
possible world in which the object exists. Causal theories of reference have since been elaborated and developed by
Michael Devitt,
Keith Donnellan,
David Kaplan,
Hilary Putnam,
Nathan Salmon,
Scott Soames,
Gareth Evans, and others, and are perhaps more widely held than descriptivist theories now. Notable holdouts include
John Searle,
Richard Rorty, and
Alonzo Church; also notable is the fact that
Hilary Putnam has drawn back from such a completely causal account.
Kripke also raised the prospect of
a posteriori necessities—facts that are necessarily true, though they can be known only through empirical investigation. Examples include “Hesperus is Phosphorus”, “Cicero is Tully”, and other identity claims where two names refer to the same object.
Finally, Kripke gave an argument against
identity materialism in the
philosophy of mind, the view that every mental fact is identical with some physical fact (
See talk). Kripke argued that the only way to defend this identity is as an
a posteriori necessary identity, but that such an identity—e.g., pain is C-fibers firing—could not be necessary, given the possibility of pain that has nothing to do with C-fibers firing. Similar arguments have been proposed by
David Chalmers.
Kripke delivered the
John Locke lectures in philosophy at
Oxford in
1973. Titled
Reference and Existence, they are in many respects a continuation of
Naming and Necessity, and deal with the subjects of
fictional names and perceptual error. They have never been published and the transcript is officially available only in a reading copy in the university philosophy library, which cannot be copied or cited without Kripke's permission. In fact many copies are informally circulated among philosophers. Its influence, though considerable, is thus difficult to trace. However, it has been extensively referred to by some philosophers, particularly
Gareth Evans and
Nathan Salmon.
Kripke also made interesting contributions to the study of the later
Wittgenstein in lectures published as
Wittgenstein on Rules and Private Language, although his work here has been faulted for being not particularly true to the historical Wittgenstein. Indeed, many philosophers refer to the subject of Kripke's book as "
Kripkenstein," on the grounds that the argument it presents would not have been endorsed by Wittgenstein. (For alternative readings of Wittgenstein, see Colin McGinn's
Wittgenstein on Meaning.) Kripke's book has also been faulted for not giving credit to other authors who interpreted Wittgenstein similarly (see Robert J. Fogelin's
Wittgenstein). Kripke's influence has been substantial, but much of his work, unfortunately, exists only in tape-recorded or transcript form.
In his 1975 article "Outline of a Theory of Truth", Kripke showed that a language can consistently contain its own
truth predicate, which was deemed impossible by
Alfred Tarski, a pioneer in the area of formal theories of truth. The trick involves letting truth be a partially defined property over the set of grammatically well-formed sentences in the language. Kripke showed how to do this recursively by starting from the set of expressions in a language which do not contain the truth predicate, defining a truth predicate over just that segment: this adds new sentences to the language, and truth is in turn defined for all of them. Unlike Tarski's approach, however, Kripke's lets "truth" be the union of all of these definition-stages; after a denumerable infinity of steps the language reaches a "fixed point" such that using Kripke's method to expand the truth-predicate does
not change the language any further. Such a fixed point can then be taken as the basic form of a natural language containing its own truth predicate. But this predicate is undefined for any sentences that do not, so to speak, "bottom out" in simpler sentences not containing a truth predicate. That is, "'Snow is white' is true" is well-defined, as is "'"Snow is white" is true' is true," and so forth, but neither "This sentence is true" nor "This sentence is not true" receive truth-conditions; they are, in Kripke's terms, "ungrounded."
In late January 2006, Kripke attended a conference celebrating his 65th birthday and work at the Graduate Center of the City University of New York, and delivered a 70-minute talk on "The First Person", discussing the meaning and reference of the pronoun "I". (
New York Times, January 28, 2006).
* 1959. "A Completeness Theorem in Modal Logic",
Journal of Symbolic Logic 24(1):1â€"14.
* 1962. "The Undecidability of Monadic Modal Quantification Theory",
Zeitschrift für Mathematische Logik und Grundlagen der Mathematik 8:113â€"116
* 1963. "Semantical Considerations in Modal Logic",
Acta Philosophica Fennica 16:83â€"94
* 1963. "Semantical Analysis of Modal Logic I: Normal Modal Propositional Calculi",
Zeitschrift für Mathematische Logik und Grundlagen der Mathematik 9:67â€"96
* 1965. "Semantical Analysis of Intuitionistic Logic I", In
Formal Systems and Recursive Functions, edited by M. Dummett and J. N. Crossley. Amsterdam: North-Holland Publishing Co.
* 1965. "Semantical Analysis of Modal Logic II: Non-Normal Modal Propositional Calculi", In
The Theory of Models, edited by J. W. Addison, L. Henkin and A. Tarski. Amsterdam: North-Holland Publishing Co.
* 1971. "Identity and Necessity", In
Identity and Individuation, edited by M. K. Munitz. New York: New York University Press.
* 1972 (1980). "Naming and Necessity", In
Semantics of Natural Language, edited by D. Davidson and G. Harman. Dordrecht; Boston: Reidel. Sets out the
causal theory of reference.
* 1975. "Outline of a Theory of Truth",
Journal of Philosophy 72:690â€"716. Sets his theory of truth (against Alfred Tarski), where an object language can contain its own truth predicate.
* 1977. "Speaker's Reference and Semantic Reference",
Midwest Studies in Philosophy 2:255â€"276
* 1979. "A Puzzle about Belief", In
Meaning and Use, edited by A. Margalit. Dordrecht and Boston: Reidel.
* 1980.
Naming and Necessity. Cambridge, Mass.: Harvard University Press. ISBN 0674598458 and reprints 1972.
* 1982.
Wittgenstein on Rules and Private Language: an Elementary Exposition. Cambridge, Mass.: Harvard University Press. ISBN 0674954017. Sets out his interpretation of
Wittgenstein aka
Kripkenstein.
* 2005. "Russell's Notion of Scope",
Mind 114:1005â€"1037
*G.W. Fitch (2005),
Saul Kripke. ISBN 0773528857.
*Scott Soames (2002),
Beyond Rigidity: The Unfinished Semantic Agenda of Naming and Necessity. ISBN 0195145291.
*Christopher Hughes (2004),
Kripke : Names, Necessity, and Identity. ISBN 0198241070.
*
Philosophy Professor information*
Saul Kripke, Genius Logician by Andreas Saugstad, February 25, 2001
*
1st World Congress on Universal Logic, Switzerland, 2005 â€" attended by Kripke
*
The Origins and Nature of Computation, Israel, 2006 â€" attended by Kripke
