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Core Concepts

Abduction
Belief
Best Explanation
Cause
Certainty
Chance
Coherence
Correspondence
Decoherence
Divided Line
Downward Causation
Emergence
Emergent Dualism
ERR
Identity Theory
Infinite Regress
Information
Intension/Extension
Intersubjectivism
Justification
Materialism
Meaning
Mental Causation
Multiple Realizability
Naturalism
Necessity
Possible Worlds
Postmodernism
Probability
Realism
Reductionism
Schrödinger's Cat
Supervenience
Truth
Universals

Philosophers

Mortimer Adler
Rogers Albritton
Alexander of Aphrodisias
Samuel Alexander
William Alston
Anaximander
G.E.M.Anscombe
Anselm
Louise Antony
Thomas Aquinas
Aristotle
David Armstrong
Harald Atmanspacher
Robert Audi
Augustine
J.L.Austin
A.J.Ayer
Alexander Bain
Mark Balaguer
Jeffrey Barrett
William Barrett
William Belsham
Henri Bergson
George Berkeley
Isaiah Berlin
Richard J. Bernstein
Bernard Berofsky
Robert Bishop
Max Black
Susanne Bobzien
Emil du Bois-Reymond
Hilary Bok
Laurence BonJour
George Boole
Émile Boutroux
F.H.Bradley
C.D.Broad
Michael Burke
Lawrence Cahoone
C.A.Campbell
Joseph Keim Campbell
Rudolf Carnap
Carneades
Ernst Cassirer
David Chalmers
Roderick Chisholm
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Cicero
Randolph Clarke
Samuel Clarke
Anthony Collins
Antonella Corradini
Diodorus Cronus
Jonathan Dancy
Donald Davidson
Mario De Caro
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Jacques Derrida
René Descartes
Richard Double
Fred Dretske
John Dupré
John Earman
Laura Waddell Ekstrom
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Herbert Feigl
Arthur Fine
John Martin Fischer
Frederic Fitch
Owen Flanagan
Luciano Floridi
Philippa Foot
Alfred Fouilleé
Harry Frankfurt
Richard L. Franklin
Michael Frede
Gottlob Frege
Peter Geach
Edmund Gettier
Carl Ginet
Alvin Goldman
Gorgias
Nicholas St. John Green
H.Paul Grice
Ian Hacking
Ishtiyaque Haji
Stuart Hampshire
W.F.R.Hardie
Sam Harris
William Hasker
R.M.Hare
Georg W.F. Hegel
Martin Heidegger
Heraclitus
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Shadsworth Hodgson
Baron d'Holbach
Ted Honderich
Pamela Huby
David Hume
Ferenc Huoranszki
William James
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Robert Kane
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Jaegwon Kim
William King
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Thomas Kuhn
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Christoph Lehner
Keith Lehrer
Gottfried Leibniz
Jules Lequyer
Leucippus
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George Henry Lewes
C.I.Lewis
David Lewis
Peter Lipton
C. Lloyd Morgan
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Michael Lockwood
E. Jonathan Lowe
John R. Lucas
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Ruth Barcan Marcus
James Martineau
Storrs McCall
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Michael McKenna
Brian McLaughlin
John McTaggart
Paul E. Meehl
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Trenton Merricks
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Dickinson Miller
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John Norton
P.H.Nowell-Smith
Robert Nozick
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Timothy O'Connor
Parmenides
David F. Pears
Charles Sanders Peirce
Derk Pereboom
Steven Pinker
Plato
Karl Popper
Porphyry
Huw Price
H.A.Prichard
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Hilary Putnam
Willard van Orman Quine
Frank Ramsey
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Michael Rea
Thomas Reid
Charles Renouvier
Nicholas Rescher
C.W.Rietdijk
Richard Rorty
Josiah Royce
Bertrand Russell
Paul Russell
Gilbert Ryle
Jean-Paul Sartre
Kenneth Sayre
T.M.Scanlon
Moritz Schlick
Arthur Schopenhauer
John Searle
Wilfrid Sellars
Alan Sidelle
Ted Sider
Henry Sidgwick
Walter Sinnott-Armstrong
J.J.C.Smart
Saul Smilansky
Michael Smith
Baruch Spinoza
L. Susan Stebbing
Isabelle Stengers
George F. Stout
Galen Strawson
Peter Strawson
Eleonore Stump
Francisco Suárez
Richard Taylor
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R. Jay Wallace
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Roy Weatherford
C.F. von Weizsäcker
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Alfred North Whitehead
David Widerker
David Wiggins
Bernard Williams
Timothy Williamson
Ludwig Wittgenstein
Susan Wolf

Scientists

Michael Arbib
Walter Baade
Bernard Baars
Jeffrey Bada
Leslie Ballentine
Gregory Bateson
John S. Bell
Mara Beller
Charles Bennett
Ludwig von Bertalanffy
Susan Blackmore
Margaret Boden
David Bohm
Niels Bohr
Ludwig Boltzmann
Emile Borel
Max Born
Satyendra Nath Bose
Walther Bothe
Hans Briegel
Leon Brillouin
Stephen Brush
Henry Thomas Buckle
S. H. Burbury
Donald Campbell
Anthony Cashmore
Eric Chaisson
Gregory Chaitin
Jean-Pierre Changeux
Arthur Holly Compton
John Conway
John Cramer
Francis Crick
E. P. Culverwell
Antonio Damasio
Olivier Darrigol
Charles Darwin
Richard Dawkins
Terrence Deacon
Lüder Deecke
Richard Dedekind
Louis de Broglie
Stanislas Dehaene
Max Delbrück
Abraham de Moivre
Paul Dirac
Hans Driesch
John Eccles
Arthur Stanley Eddington
Gerald Edelman
Paul Ehrenfest
Albert Einstein
Hugh Everett, III
Franz Exner
Richard Feynman
R. A. Fisher
David Foster
Joseph Fourier
Philipp Frank
Steven Frautschi
Edward Fredkin
Lila Gatlin
Michael Gazzaniga
GianCarlo Ghirardi
J. Willard Gibbs
Nicolas Gisin
Paul Glimcher
Thomas Gold
A. O. Gomes
Brian Goodwin
Joshua Greene
Jacques Hadamard
Mark Hadley
Patrick Haggard
J. B. S. Haldane
Stuart Hameroff
Augustin Hamon
Sam Harris
Hyman Hartman
John-Dylan Haynes
Donald Hebb
Martin Heisenberg
Werner Heisenberg
John Herschel
Art Hobson
Jesper Hoffmeyer
E. T. Jaynes
William Stanley Jevons
Roman Jakobson
Pascual Jordan
Ruth E. Kastner
Stuart Kauffman
Martin J. Klein
William R. Klemm
Christof Koch
Simon Kochen
Hans Kornhuber
Stephen Kosslyn
Ladislav Kovàč
Leopold Kronecker
Rolf Landauer
Alfred Landé
Pierre-Simon Laplace
David Layzer
Joseph LeDoux
Benjamin Libet
Seth Lloyd
Hendrik Lorentz
Josef Loschmidt
Ernst Mach
Donald MacKay
Henry Margenau
James Clerk Maxwell
Ernst Mayr
John McCarthy
Warren McCulloch
George Miller
Stanley Miller
Ulrich Mohrhoff
Jacques Monod
Emmy Noether
Alexander Oparin
Abraham Pais
Howard Pattee
Wolfgang Pauli
Massimo Pauri
Roger Penrose
Steven Pinker
Colin Pittendrigh
Max Planck
Susan Pockett
Henri Poincaré
Daniel Pollen
Ilya Prigogine
Hans Primas
Adolphe Quételet
Jürgen Renn
Juan Roederer
Jerome Rothstein
David Ruelle
Tilman Sauer
Jürgen Schmidhuber
Erwin Schrödinger
Aaron Schurger
Claude Shannon
Charles Sherrington
David Shiang
Herbert Simon
Dean Keith Simonton
B. F. Skinner
Lee Smolin
Ray Solomonoff
Roger Sperry
John Stachel
Henry Stapp
Tom Stonier
Antoine Suarez
Leo Szilard
Max Tegmark
William Thomson (Kelvin)
Giulio Tononi
Peter Tse
Vlatko Vedral
Heinz von Foerster
John von Neumann
John B. Watson
Daniel Wegner
Steven Weinberg
Paul A. Weiss
John Wheeler
Wilhelm Wien
Norbert Wiener
Eugene Wigner
E. O. Wilson
Stephen Wolfram
H. Dieter Zeh
Ernst Zermelo
Wojciech Zurek
Konrad Zuse
Fritz Zwicky

Presentations

Biosemiotics
Free Will
Mental Causation
James Symposium

 
C.I. Lewis

C.I. Lewis was prominent in the Harvard Philosophy Department between the era of William James and Willard van Orman Quine. Like Quine, Lewis' specialty was logic. He began as an Absolute Idealist following the thought of his adviser Josiah Royce. Royce was the principal spokesman in America for the school of idealists in Europe, notably F. H. Bradley in England, who were transcendental idealists in the tradition of Georg Wilhelm Friedrich Hegel

Lewis' early graduate student work was a criticism of Bertrand Russell's definition of "material implication" (a → b as "a implies b") in the Principia Mathematica.

Lewis proposed a definition for "strict implication" which prevented false antecedents from implying true consequents. In this work he defined an intensional modal operator that marked the beginning of modern modal logic and possible worlds analysis of various truths.

Lewis' first office as a Harvard Professor was the room in Widener Library that contained all the manuscripts of Charles Sanders Peirce. Lewis began his career as an Idealist, following his thesis adviser Josiah Royce.

Lewis was thus a "postmodern" who rejected the "grounds" by modern and traditional thinkers.
Influenced by Peirce's arguments, Lewis in 1923 proposed the radical idea that a priori systems of thought are invented by humans and validated empirically.

In a short paper, A Pragmatic Conception of the A Priori, Lewis claimed that there is not just one logic, but many logics from which we must choose the one that best explains our experience. This eventually is the basis for Quine's naturalization of epistemology, and perhaps Quine's attack on the analytic/synthetic "dogma," which distinction was defended by P. F. Strawson and H. Paul Grice.

After a decade browsing through Peirce's papers, Lewis declared himself a "conceptual pragmatist" in his 1929 book Mind and the World Order. The Roycean, Kantian, and Hegelian transcendental absolute mind imposing order and regulative principles on the world disappeared from Lewis' thought, replaced by the action of human minds constructing various a priori conceptual schemes to make sense of the raw perceptions of the world that Lewis called the "given."

Following Peirce, Lewis took the "truth" or meaning of a concept to be its consequences in experience, and he thought of concepts as relations. Influenced by Percy Bridgman's operationalism, Lewis could bypass the problem of different subjective experiences for different persons, something his Harvard colleague Ralph Barton Perry and fellow "New Realists" had called "the egocentric predicament."

One such subjective epistemological problem is spectrum inversion - "what I see as red, you see as green."

What is important is how you act on the perception. As long as you always stop at a traffic light that I see as red, we have the same relation of information in our minds to information in objects and processes in the world. Lewis concluded:

"If your hours are felt as twice as long as mine, your pounds twice as heavy, that makes no difference, which can be tested, in our assignment of physical properties to things."
Lewis criticized the Logical Positivists, including Russell but also Rudolf Carnap and his Vienna Circle colleagues. They were empiricists like Lewis, but focused on the linguistic meaning of a statement, which they found in its direct verification by perception. Carnap felt we had no choice but to build up our knowledge of the world logically (Der logische Aufbau der Welt) on what he called "methodological solipsism," despite the egocentric predicament.

Lewis thought the verification of empirical meaning depended on experience, and more importantly on the common relational experiences of many observers. This came to be called pragmatic meaning. The positivist idea was called semantic meaning.

The Positivists hoped to build up their system of knowledge starting with "logical atoms" that could be the foundation on which all knowledge could be made certain. They believed that logic and mathematics could be shown to have an a priori truth and many basic linguistic concepts could be regarded as analytic - since they were true by definition, such as "a bachelor is an unmarried man."

Lewis pointed out that all such analytic linguistic definitions could have been otherwise (indeed they are in other languages, as well as in other contexts) and the Kantian notion of a priori truths had failed. Kant's idea that Euclidean geometry and deterministic Newtonian physics were fundamental categories of the understanding was simply wrong.

We choose from among the possible geometries based on their usefulness in explaining experience. And so must we choose among possible logics, by empirically testing their applicability in the world. Long before Quine's Two Dogmas of Empiricism, Lewis knew that analytic truths have an empirical or "synthetic" basis. And that knowledge depends on relations between concepts and not atomistic reductions of statements to their supporting observation sentences.

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Notes

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Bibliography

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