David Kellogg Lewis
Encyclopedia
David Kellogg Lewis was an American philosopher. Lewis taught briefly at UCLA and then at Princeton
from 1970 until his death. He is also closely associated with Australia
, whose philosophical community he visited almost annually for more than thirty years. He has made contributions in philosophy of language
, philosophy of mind
, metaphysics
, epistemology, and philosophical logic
. He is probably best known for his controversial modal realist
stance: that (i) possible worlds
exist, (ii) every possible world is a concrete entity, (iii) any possible world is causally and spatiotemporally isolated from any other possible world, and (iv) our world is among the possible worlds. This view has a wide variety of uses in providing a framework for philosophical thought, including providing a non-modal analysis of necessity and possibility. A recent poll conducted among philosophers ranked Lewis the thirteenth most important philosopher of the past 200 years.
, Ohio
, to John D. Lewis, a Professor of Government at Oberlin College
, and Ruth Ewart Kelloggs Lewis, a distinguished medieval historian. The formidable intellect for which he was known later in his life was already manifest during his years at Oberlin High School, when he attended college lectures in chemistry
. He went on to Swarthmore College
and spent a year at Oxford (1959–1960), where he was tutored by Iris Murdoch
and attended lectures by Gilbert Ryle
, H. P. Grice, P. F. Strawson
, and J. L. Austin
. It was his year at Oxford
that played a seminal role in his decision to study philosophy, and which made him the quintessentially analytic
philosopher that he would soon become. Lewis went on to receive his Ph.D from Harvard in 1967, where he studied under W. V. O. Quine, many of whose views he came to repudiate. It was there that his connection with Australia
was first established when he took a seminar with J. J. C. Smart
, a leading Australian philosopher. "I taught David Lewis," Smart would say in later years, "Or rather, he taught me."
to analyze the nature of social conventions; it won the American Philosophical Association
's first Franklin Matchette Prize for the best book published in philosophy by a philosopher under 40 years old. Lewis claimed that social conventions, such as the convention in most states that one drives on the right (not on the left), the convention that the original caller will re-call if a phone conversation is interrupted, etc., are solutions to so-called "'co-ordination problems'". Co-ordination problems were at the time of Lewis's book a much under-discussed kind of game-theoretical problem; most of the game-theoretical discussion had circulated around problems where the participants are in conflict, such as the prisoner's dilemma
.
Co-ordination problems are problematic, for, though the participants have common interests, there are several solutions. Sometimes, one of the solutions may be "'salient'", a concept invented by the game-theorist and economist Thomas Schelling
(by whom Lewis was much inspired). For example, a co-ordination problem that has the form of a meeting may have a salient solution if there is only one possible spot to meet in town. But in most cases, we must rely on what Lewis calls "precedent" in order to get a salient solution. If both participants know that a particular co-ordination problem, say "which side should we drive on?" has been solved in the same way numerous times before, both know that both know this, both know that both know that both know this, etc. (this particular state Lewis calls common knowledge
, and it has since been much discussed by philosophers and game theorists), then they will easily solve the problem. That they have solved the problem successfully will be seen by even more people, and thus the convention will spread in the society. A convention is thus a behavioural regularity that sustains itself because it serves the interests of everyone involved. Another important feature of a convention is that a convention could be entirely different: one could just as well drive on the left; it is more or less arbitrary that one drives on the right in the USA, for example.
Lewis's main goal in the book, however, wasn't simply to provide an account of convention but rather to investigate the "platitude that language is ruled by convention" (Convention, p. 1.) The last two chapters of the book (Signalling Systems and Conventions of Language; cf. also "Languages and Language", 1975) make the case that the use of a language in a population consists of conventions of truthfulness and trust among members of the population. Lewis recasts in this framework notions as those of truth and analyticity, claiming that they are better understood as relations between sentences and a language, rather than as properties of sentences.
conditionals in terms of the theory of possible worlds
. He had already proposed it in some of his earlier papers - "Counterpart Theory and Quantified Modal Logic" (1968), "Anselm and Actuality" (1970), and "Counterparts of Persons and their Bodies" (1971). In spite of significant technical advantages promised by this approach, the theory was widely considered to be too implausible to be taken literally, as Lewis urged it should be. Most often the idea that there exists an infinite number of causally isolated universes, each as real as our own but different from it in some way, and that furthermore that alluding to objects in this universe as necessary in order to explain what makes certain counterfactual statements true but not others, meets with what Lewis calls the "incredulous stare" (Lewis, OPW, 2005, pg. 135-137). Lewis defends and elaborates his theory of extreme modal realism
, while insisting that there is nothing extreme about it, in On the Plurality of Worlds
(1986). Lewis acknowledges that his theory is contrary to common sense, but believes that its advantages far outweigh this disadvantage, and that therefore we should not be hesitant to pay this price.
According to Lewis, what makes a counterfactual conditional
of the form
true is that there is a world, as concrete as ours and significantly similar to it, in which my counterpart makes rather than misses the shot and the counterpart of our team wins the game. Had there been a world even more similar to ours in which my counterpart makes the shot but the counterpart of our team still loses the counterfactual would have been false. When we speak of counterfactual possibilities we speak of what is the case in some possible world or worlds. According to Lewis, "actual" is merely an indexical label we give to a world when we locate ourselves in it. Things are necessarily true when they are true in all possible worlds. (Note that Lewis is not the first one to speak of possible worlds in this context. Leibniz and C.I. Lewis, for example, both speak of possible worlds as a way of thinking about possibility and necessity, and some of David Kaplan
's early work is on the counterpart theory
. Lewis's original suggestion was that all possible worlds are equally concrete, and the world in which we find ourselves is no more real than any other possible world.)
once put it, a presidential candidate could not care less whether someone else, in another world, wins an election, but with whether he himself could have won it (Kripke 1980, p. 45). A more basic criticism is that introducing so many entities into our ontology
violates the maxim of Occam's razor
, which tells us not to multiply theoretical entities beyond what is necessary to explain the facts our theories aim to explain.
Possible worlds are employed in the work of Saul Kripke
and many others, but not in the concrete sense propounded by Lewis. While none of these alternative approaches have found anything near universal acceptance, very few philosophers accept Lewis's particular brand of modal realism.
Lewis published five volumes containing 99 papers - almost all of the papers he published during his lifetime. These papers discuss his counterfactual theory of causation
, the concept of semantic score, a contextualist analysis of knowledge, a dispositional theory of value
, among many other topics.
Lewis's last monograph, Parts of Classes (1991), on the foundations of mathematics
, sketched a reduction of set theory
and Peano arithmetic to mereology
and plural quantification
. Very soon after its publication, Lewis became dissatisfied with some aspects of its argument; it is currently out of print (his paper "Mathematics in megethology," in "Papers in Philosophical Logic," is partly a summary and partly a revision of "Parts of Classes").
. His direct and indirect influence is evident in the work of many prominent philosophers of the current generation.
failure. In July 2000 he received a kidney transplant from his wife Stephanie. The transplant allowed him to work and travel for another year, before he died suddenly and unexpectedly from further complications of his diabetes, on October 14, 2001.
Since his death a number of posthumous papers have been published, on topics ranging from truth and causation to philosophy of physics. Lewisian Themes, a collection of papers on his philosophy, was published in 2004.
Princeton University
Princeton University is a private research university located in Princeton, New Jersey, United States. The school is one of the eight universities of the Ivy League, and is one of the nine Colonial Colleges founded before the American Revolution....
from 1970 until his death. He is also closely associated with Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, whose philosophical community he visited almost annually for more than thirty years. He has made contributions in philosophy of language
Philosophy of language
Philosophy of language is the reasoned inquiry into the nature, origins, and usage of language. As a topic, the philosophy of language for analytic philosophers is concerned with four central problems: the nature of meaning, language use, language cognition, and the relationship between language...
, philosophy of mind
Philosophy of mind
Philosophy of mind is a branch of philosophy that studies the nature of the mind, mental events, mental functions, mental properties, consciousness and their relationship to the physical body, particularly the brain. The mind-body problem, i.e...
, metaphysics
Metaphysics
Metaphysics is a branch of philosophy concerned with explaining the fundamental nature of being and the world, although the term is not easily defined. Traditionally, metaphysics attempts to answer two basic questions in the broadest possible terms:...
, epistemology, and philosophical logic
Philosophical logic
Philosophical logic is a term introduced by Bertrand Russell to represent his idea that the workings of natural language and thought can only be adequately represented by an artificial language; essentially it was his formalization program for the natural language...
. He is probably best known for his controversial modal realist
Modal realism
Modal realism is the view, notably propounded by David Kellogg Lewis, that all possible worlds are as real as the actual world. It is based on the following tenets: possible worlds exist; possible worlds are not different in kind from the actual world; possible worlds are irreducible entities; the...
stance: that (i) possible worlds
Possible world
In philosophy and logic, the concept of a possible world is used to express modal claims. The concept of possible worlds is common in contemporary philosophical discourse and has also been disputed.- Possibility, necessity, and contingency :...
exist, (ii) every possible world is a concrete entity, (iii) any possible world is causally and spatiotemporally isolated from any other possible world, and (iv) our world is among the possible worlds. This view has a wide variety of uses in providing a framework for philosophical thought, including providing a non-modal analysis of necessity and possibility. A recent poll conducted among philosophers ranked Lewis the thirteenth most important philosopher of the past 200 years.
Early life and education
Lewis was born in OberlinOberlin, Ohio
Oberlin is a city in Lorain County, Ohio, United States, to the south and west of Cleveland. Oberlin is perhaps best known for being the home of Oberlin College, a liberal arts college and music conservatory with approximately 3,000 students...
, Ohio
Ohio
Ohio is a Midwestern state in the United States. The 34th largest state by area in the U.S.,it is the 7th‑most populous with over 11.5 million residents, containing several major American cities and seven metropolitan areas with populations of 500,000 or more.The state's capital is Columbus...
, to John D. Lewis, a Professor of Government at Oberlin College
Oberlin College
Oberlin College is a private liberal arts college in Oberlin, Ohio, noteworthy for having been the first American institution of higher learning to regularly admit female and black students. Connected to the college is the Oberlin Conservatory of Music, the oldest continuously operating...
, and Ruth Ewart Kelloggs Lewis, a distinguished medieval historian. The formidable intellect for which he was known later in his life was already manifest during his years at Oberlin High School, when he attended college lectures in chemistry
Chemistry
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....
. He went on to Swarthmore College
Swarthmore College
Swarthmore College is a private, independent, liberal arts college in the United States with an enrollment of about 1,500 students. The college is located in the borough of Swarthmore, Pennsylvania, 11 miles southwest of Philadelphia....
and spent a year at Oxford (1959–1960), where he was tutored by Iris Murdoch
Iris Murdoch
Dame Iris Murdoch DBE was an Irish-born British author and philosopher, best known for her novels about political and social questions of good and evil, sexual relationships, morality, and the power of the unconscious...
and attended lectures by Gilbert Ryle
Gilbert Ryle
Gilbert Ryle , was a British philosopher, a representative of the generation of British ordinary language philosophers that shared Wittgenstein's approach to philosophical problems, and is principally known for his critique of Cartesian dualism, for which he coined the phrase "the ghost in the...
, H. P. Grice, P. F. Strawson
P. F. Strawson
Sir Peter Frederick Strawson FBA was an English philosopher. He was the Waynflete Professor of Metaphysical Philosophy at the University of Oxford from 1968 to 1987. Before that he was appointed as a college lecturer at University College, Oxford in 1947 and became a tutorial fellow the...
, and J. L. Austin
J. L. Austin
John Langshaw Austin was a British philosopher of language, born in Lancaster and educated at Shrewsbury School and Balliol College, Oxford University. Austin is widely associated with the concept of the speech act and the idea that speech is itself a form of action...
. It was his year at Oxford
University of Oxford
The University of Oxford is a university located in Oxford, United Kingdom. It is the second-oldest surviving university in the world and the oldest in the English-speaking world. Although its exact date of foundation is unclear, there is evidence of teaching as far back as 1096...
that played a seminal role in his decision to study philosophy, and which made him the quintessentially analytic
Analytic philosophy
Analytic philosophy is a generic term for a style of philosophy that came to dominate English-speaking countries in the 20th century...
philosopher that he would soon become. Lewis went on to receive his Ph.D from Harvard in 1967, where he studied under W. V. O. Quine, many of whose views he came to repudiate. It was there that his connection with Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
was first established when he took a seminar with J. J. C. Smart
J. J. C. Smart
John Jamieson Carswell "Jack" Smart AC is an Australian philosopher and academic who is currently Emeritus Professor of Philosophy at Monash University, Australia...
, a leading Australian philosopher. "I taught David Lewis," Smart would say in later years, "Or rather, he taught me."
Early work on convention
Lewis's first monograph was Convention: A Philosophical Study (1969), which is based on his doctoral dissertation and uses concepts of game theoryGame theory
Game theory is a mathematical method for analyzing calculated circumstances, such as in games, where a person’s success is based upon the choices of others...
to analyze the nature of social conventions; it won the American Philosophical Association
American Philosophical Association
The American Philosophical Association is the main professional organization for philosophers in the United States. Founded in 1900, its mission is to promote the exchange of ideas among philosophers, to encourage creative and scholarly activity in philosophy, to facilitate the professional work...
's first Franklin Matchette Prize for the best book published in philosophy by a philosopher under 40 years old. Lewis claimed that social conventions, such as the convention in most states that one drives on the right (not on the left), the convention that the original caller will re-call if a phone conversation is interrupted, etc., are solutions to so-called "'co-ordination problems'". Co-ordination problems were at the time of Lewis's book a much under-discussed kind of game-theoretical problem; most of the game-theoretical discussion had circulated around problems where the participants are in conflict, such as the prisoner's dilemma
Prisoner's dilemma
The prisoner’s dilemma is a canonical example of a game, analyzed in game theory that shows why two individuals might not cooperate, even if it appears that it is in their best interest to do so. It was originally framed by Merrill Flood and Melvin Dresher working at RAND in 1950. Albert W...
.
Co-ordination problems are problematic, for, though the participants have common interests, there are several solutions. Sometimes, one of the solutions may be "'salient'", a concept invented by the game-theorist and economist Thomas Schelling
Thomas Schelling
Thomas Crombie Schelling is an American economist and professor of foreign affairs, national security, nuclear strategy, and arms control at the School of Public Policy at University of Maryland, College Park. He is also co-faculty at the New England Complex Systems Institute...
(by whom Lewis was much inspired). For example, a co-ordination problem that has the form of a meeting may have a salient solution if there is only one possible spot to meet in town. But in most cases, we must rely on what Lewis calls "precedent" in order to get a salient solution. If both participants know that a particular co-ordination problem, say "which side should we drive on?" has been solved in the same way numerous times before, both know that both know this, both know that both know that both know this, etc. (this particular state Lewis calls common knowledge
Common knowledge (logic)
Common knowledge is a special kind of knowledge for a group of agents. There is common knowledge of p in a group of agents G when all the agents in G know p, they all know that they know p, they all know that they all know that they know p, and so on ad infinitum.The concept was first introduced in...
, and it has since been much discussed by philosophers and game theorists), then they will easily solve the problem. That they have solved the problem successfully will be seen by even more people, and thus the convention will spread in the society. A convention is thus a behavioural regularity that sustains itself because it serves the interests of everyone involved. Another important feature of a convention is that a convention could be entirely different: one could just as well drive on the left; it is more or less arbitrary that one drives on the right in the USA, for example.
Lewis's main goal in the book, however, wasn't simply to provide an account of convention but rather to investigate the "platitude that language is ruled by convention" (Convention, p. 1.) The last two chapters of the book (Signalling Systems and Conventions of Language; cf. also "Languages and Language", 1975) make the case that the use of a language in a population consists of conventions of truthfulness and trust among members of the population. Lewis recasts in this framework notions as those of truth and analyticity, claiming that they are better understood as relations between sentences and a language, rather than as properties of sentences.
Counterfactuals and modal realism
Lewis went on to publish Counterfactuals (1973), which contained an analysis of counterfactualCounterfactual
Counterfactual may refer to:* Counterfactual conditional, a grammatical form * Counterfactual subjunctive, grammatical forms which in English are known as the past and pluperfect forms of the subjunctive mood* Counterfactual thinking* Counterfactual history* Alternate history, a literary genre*...
conditionals in terms of the theory of possible worlds
Possible Worlds
Possible Worlds may refer to:* Possible worlds, a concept in philosophy* Possible Worlds , by John Mighton** Possible Worlds , by Robert Lepage, based on the Mighton play* Possible Worlds , by Peter Porter...
. He had already proposed it in some of his earlier papers - "Counterpart Theory and Quantified Modal Logic" (1968), "Anselm and Actuality" (1970), and "Counterparts of Persons and their Bodies" (1971). In spite of significant technical advantages promised by this approach, the theory was widely considered to be too implausible to be taken literally, as Lewis urged it should be. Most often the idea that there exists an infinite number of causally isolated universes, each as real as our own but different from it in some way, and that furthermore that alluding to objects in this universe as necessary in order to explain what makes certain counterfactual statements true but not others, meets with what Lewis calls the "incredulous stare" (Lewis, OPW, 2005, pg. 135-137). Lewis defends and elaborates his theory of extreme modal realism
Modal realism
Modal realism is the view, notably propounded by David Kellogg Lewis, that all possible worlds are as real as the actual world. It is based on the following tenets: possible worlds exist; possible worlds are not different in kind from the actual world; possible worlds are irreducible entities; the...
, while insisting that there is nothing extreme about it, in On the Plurality of Worlds
On the Plurality of Worlds
On the Plurality of Worlds is a book by the philosopher David Lewis that defends the thesis of modal realism, "The thesis states that the world we are part of is but one of a plurality of worlds," as he writes in the Preface, "and that we who inhabit this world are only a few out of all the...
(1986). Lewis acknowledges that his theory is contrary to common sense, but believes that its advantages far outweigh this disadvantage, and that therefore we should not be hesitant to pay this price.
According to Lewis, what makes a counterfactual conditional
Counterfactual conditional
A counterfactual conditional, subjunctive conditional, or remote conditional, abbreviated , is a conditional statement indicating what would be the case if its antecedent were true...
of the form
"Had I made that shot our team would have won the game."
true is that there is a world, as concrete as ours and significantly similar to it, in which my counterpart makes rather than misses the shot and the counterpart of our team wins the game. Had there been a world even more similar to ours in which my counterpart makes the shot but the counterpart of our team still loses the counterfactual would have been false. When we speak of counterfactual possibilities we speak of what is the case in some possible world or worlds. According to Lewis, "actual" is merely an indexical label we give to a world when we locate ourselves in it. Things are necessarily true when they are true in all possible worlds. (Note that Lewis is not the first one to speak of possible worlds in this context. Leibniz and C.I. Lewis, for example, both speak of possible worlds as a way of thinking about possibility and necessity, and some of David Kaplan
David Kaplan (philosopher)
David Benjamin Kaplan is an American philosopher and logician teaching at UCLA. His philosophical work focuses on logic, philosophical logic, modality, philosophy of language, metaphysics, and epistemology. He is best known for his work on demonstratives, on propositions, and on reference in...
's early work is on the counterpart theory
Counterpart theory
In philosophy, specifically in the area of modal metaphysics, counterpart theory is an alternative to standard possible-worlds semantics for interpreting quantified modal logic. Counterpart theory still presupposes possible worlds, but differs in certain important respects from the Kripkean view...
. Lewis's original suggestion was that all possible worlds are equally concrete, and the world in which we find ourselves is no more real than any other possible world.)
Criticisms
This theory has faced a number of criticisms. In particular, it is not clear how we could know what goes on in other worlds. After all, they are causally disconnected from ours; we can't look into them to see what is going on there. A related objection is that, while people are concerned with what they could have done, they are not concerned with what some people in other worlds, no matter how similar to them, do. As Saul KripkeSaul Kripke
Saul Aaron Kripke is an American philosopher and logician. He is a professor emeritus at Princeton and teaches as a Distinguished Professor of Philosophy at the CUNY Graduate Center...
once put it, a presidential candidate could not care less whether someone else, in another world, wins an election, but with whether he himself could have won it (Kripke 1980, p. 45). A more basic criticism is that introducing so many entities into our ontology
Ontology
Ontology is the philosophical study of the nature of being, existence or reality as such, as well as the basic categories of being and their relations...
violates the maxim of Occam's razor
Occam's razor
Occam's razor, also known as Ockham's razor, and sometimes expressed in Latin as lex parsimoniae , is a principle that generally recommends from among competing hypotheses selecting the one that makes the fewest new assumptions.-Overview:The principle is often summarized as "simpler explanations...
, which tells us not to multiply theoretical entities beyond what is necessary to explain the facts our theories aim to explain.
Possible worlds are employed in the work of Saul Kripke
Saul Kripke
Saul Aaron Kripke is an American philosopher and logician. He is a professor emeritus at Princeton and teaches as a Distinguished Professor of Philosophy at the CUNY Graduate Center...
and many others, but not in the concrete sense propounded by Lewis. While none of these alternative approaches have found anything near universal acceptance, very few philosophers accept Lewis's particular brand of modal realism.
Books
- Convention: A Philosophical Study, Harvard University Press 1969.
- Counterfactuals, Harvard University Press 1973; revised printing Blackwell 1986.
- Semantic Analysis: Essays Dedicated to Stig Kanger on His Fiftieth Birthday, Reidel 1974.
- On the Plurality of Worlds, Blackwell 1986.
- Parts of Classes, Blackwell 1991.
Lewis published five volumes containing 99 papers - almost all of the papers he published during his lifetime. These papers discuss his counterfactual theory of causation
Causality
Causality is the relationship between an event and a second event , where the second event is understood as a consequence of the first....
, the concept of semantic score, a contextualist analysis of knowledge, a dispositional theory of value
Theory of value
Theory of value is an ambiguous term, and may mean:*Theory of value , where value is meant as economic worth of goods and services.*Value theory, where value is meant in the philosophical sense....
, among many other topics.
- Philosophical Papers, Vol. I (1983) includes his early work on counterpart theoryCounterpart theoryIn philosophy, specifically in the area of modal metaphysics, counterpart theory is an alternative to standard possible-worlds semantics for interpreting quantified modal logic. Counterpart theory still presupposes possible worlds, but differs in certain important respects from the Kripkean view...
, and the philosophy of languagePhilosophy of languagePhilosophy of language is the reasoned inquiry into the nature, origins, and usage of language. As a topic, the philosophy of language for analytic philosophers is concerned with four central problems: the nature of meaning, language use, language cognition, and the relationship between language...
and of mindPhilosophy of mindPhilosophy of mind is a branch of philosophy that studies the nature of the mind, mental events, mental functions, mental properties, consciousness and their relationship to the physical body, particularly the brain. The mind-body problem, i.e...
; - Philosophical Papers, Vol. II (1986) includes his work on counterfactuals, causation, and decision theoryDecision theoryDecision theory in economics, psychology, philosophy, mathematics, and statistics is concerned with identifying the values, uncertainties and other issues relevant in a given decision, its rationality, and the resulting optimal decision...
. Its preface discusses "Humean Supervenience," the name Lewis gave to his overarching philosophical project; - Papers in Philosophical LogicPhilosophical logicPhilosophical logic is a term introduced by Bertrand Russell to represent his idea that the workings of natural language and thought can only be adequately represented by an artificial language; essentially it was his formalization program for the natural language...
(1998); - Papers in MetaphysicsMetaphysicsMetaphysics is a branch of philosophy concerned with explaining the fundamental nature of being and the world, although the term is not easily defined. Traditionally, metaphysics attempts to answer two basic questions in the broadest possible terms:...
and Epistemology (1999) contains "Elusive Knowledge" and "Naming the Colours," honored by being reprinted in the Philosopher's Annual for the year they were first published; - Papers in EthicsEthicsEthics, also known as moral philosophy, is a branch of philosophy that addresses questions about morality—that is, concepts such as good and evil, right and wrong, virtue and vice, justice and crime, etc.Major branches of ethics include:...
and Social PhilosophySocial philosophySocial philosophy is the philosophical study of questions about social behavior . Social philosophy addresses a wide range of subjects, from individual meanings to legitimacy of laws, from the social contract to criteria for revolution, from the functions of everyday actions to the effects of...
(2000).
Lewis's last monograph, Parts of Classes (1991), on the foundations of mathematics
Foundations of mathematics
Foundations of mathematics is a term sometimes used for certain fields of mathematics, such as mathematical logic, axiomatic set theory, proof theory, model theory, type theory and recursion theory...
, sketched a reduction of set theory
Set theory
Set theory is the branch of mathematics that studies sets, which are collections of objects. Although any type of object can be collected into a set, set theory is applied most often to objects that are relevant to mathematics...
and Peano arithmetic to mereology
Mereology
In philosophy and mathematical logic, mereology treats parts and the wholes they form...
and plural quantification
Plural quantification
In mathematics and logic, plural quantification is the theory that an individual variable x may take on plural, as well as singular values. As well as substituting individual objects such as Alice, the number 1, the tallest building in London etc...
. Very soon after its publication, Lewis became dissatisfied with some aspects of its argument; it is currently out of print (his paper "Mathematics in megethology," in "Papers in Philosophical Logic," is partly a summary and partly a revision of "Parts of Classes").
Influence
At Princeton, Lewis was a gifted mentor of young philosophers, and trained dozens of successful figures in the field, including several current Princeton faculty members, as well as people now teaching at a number of the leading philosophy departments in the U.S. Among his most prominent students are Bob Brandom, L.A. Paul, Cian Dorr, Philip Bricker, David Velleman, and Peter RailtonPeter Railton
Peter Albert Railton is John Stephenson Perrin Professor of Philosophy at the University of Michigan, Ann Arbor. He received his Ph.D. from Princeton in 1980. His research interests center on contemporary metaethics and normative ethics, as well as consequentialism...
. His direct and indirect influence is evident in the work of many prominent philosophers of the current generation.
Later life and death
Lewis suffered from severe diabetes for much of his life, which eventually grew worse and led into kidneyKidney
The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...
failure. In July 2000 he received a kidney transplant from his wife Stephanie. The transplant allowed him to work and travel for another year, before he died suddenly and unexpectedly from further complications of his diabetes, on October 14, 2001.
Since his death a number of posthumous papers have been published, on topics ranging from truth and causation to philosophy of physics. Lewisian Themes, a collection of papers on his philosophy, was published in 2004.
Selected Papers
- "Counterpart Theory and Quantified Modal Logic." Journal of Philosophy 65 (1968): pp. 113–126.
- "Truth in Fiction." American Philosophical Quarterly 15 (1978): pp. 37–46.
- "How to Define Theoretical Terms." Journal of Philosophy 67 (1979): pp. 427–46.
- "Scorekeeping in a Language Game." Journal of Philosophical Logic 8 (1979): pp. 339–59.
- "Mad pain and Martian painMad pain and Martian painMad Pain and Martian Pain is a philosophical article written by David Kellogg Lewis. Lewis argues that a theory of pain must be able to reflect the most basic intuitions of both functionalism and identity theory. As such, he proposes the existence of two beings both in pain - one whose physical...
." Readings in the Philosophy of Psychology Vol. I. N. Block, ed. Harvard University PressHarvard University PressHarvard University Press is a publishing house established on January 13, 1913, as a division of Harvard University, and focused on academic publishing. In 2005, it published 220 new titles. It is a member of the Association of American University Presses. Its current director is William P...
(1980): pp. 216–222. - "Are We Free to Break the Laws?" Theoria 47 (1981): pp. 113–21.
- "New Work for a Theory of Universals." Australasian Journal of Philosophy 61 (1983): pp. 343–77.
- "Elusive Knowledge", Australasian Journal of Philosophy, 74/4 (1996): pp. 549–567.
See also
- Lewis's GeneralizationLewis's GeneralizationLewis's Generalization is an analysis of the non-monotonic semantics of definite descriptions. It was proposed, as an aside, by David Lewis in Counterfactuals : a sort of corollary to possible world semantics...
- American philosophyAmerican philosophyAmerican philosophy is the philosophical activity or output of Americans, both within the United States and abroad. The Internet Encyclopedia of Philosophy notes that while American philosophy lacks a "core of defining features, American Philosophy can nevertheless be seen as both reflecting and...
- List of American philosophers