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Philosophers

Mortimer Adler
Rogers Albritton
Alexander of Aphrodisias
Samuel Alexander
William Alston
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 Belsham
Henri Bergson
Isaiah Berlin
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
C.A.Campbell
Joseph Keim Campbell
Rudolf Carnap
Carneades
Ernst Cassirer
David Chalmers
Roderick Chisholm
Chrysippus
Cicero
Randolph Clarke
Samuel Clarke
Anthony Collins
Antonella Corradini
Diodorus Cronus
Jonathan Dancy
Donald Davidson
Mario De Caro
Democritus
Daniel Dennett
Jacques Derrida
René Descartes
Richard Double
Fred Dretske
John Dupré
John Earman
Laura Waddell Ekstrom
Epictetus
Epicurus
Herbert Feigl
John Martin Fischer
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
R.E.Hobart
Thomas Hobbes
David Hodgson
Shadsworth Hodgson
Baron d'Holbach
Ted Honderich
Pamela Huby
David Hume
Ferenc Huoranszki
William James
Lord Kames
Robert Kane
Immanuel Kant
Tomis Kapitan
Jaegwon Kim
William King
Hilary Kornblith
Christine Korsgaard
Saul Kripke
Andrea Lavazza
Keith Lehrer
Gottfried Leibniz
Leucippus
Michael Levin
George Henry Lewes
C.I.Lewis
David Lewis
Peter Lipton
John Locke
Michael Lockwood
E. Jonathan Lowe
John R. Lucas
Lucretius
Ruth Barcan Marcus
James Martineau
Storrs McCall
Hugh McCann
Colin McGinn
Michael McKenna
Brian McLaughlin
John McTaggart
Paul E. Meehl
Uwe Meixner
Alfred Mele
Trenton Merricks
John Stuart Mill
Dickinson Miller
G.E.Moore
C. Lloyd Morgan
Thomas Nagel
Friedrich Nietzsche
John Norton
P.H.Nowell-Smith
Robert Nozick
William of Ockham
Timothy O'Connor
David F. Pears
Charles Sanders Peirce
Derk Pereboom
Steven Pinker
Plato
Karl Popper
Porphyry
Huw Price
H.A.Prichard
Hilary Putnam
Willard van Orman Quine
Frank Ramsey
Ayn Rand
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
George F. Stout
Galen Strawson
Peter Strawson
Eleonore Stump
Francisco Suárez
Richard Taylor
Kevin Timpe
Mark Twain
Peter Unger
Peter van Inwagen
Manuel Vargas
John Venn
Kadri Vihvelin
Voltaire
G.H. von Wright
David Foster Wallace
R. Jay Wallace
W.G.Ward
Ted Warfield
Roy Weatherford
William Whewell
Alfred North Whitehead
David Widerker
David Wiggins
Bernard Williams
Timothy Williamson
Ludwig Wittgenstein
Susan Wolf

Scientists

Michael Arbib
Bernard Baars
Gregory Bateson
John S. Bell
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
Jean-Pierre Changeux
Arthur Holly Compton
John Conway
John Cramer
E. P. Culverwell
Charles Darwin
Terrence Deacon
Louis de Broglie
Max Delbrück
Abraham de Moivre
Paul Dirac
Hans Driesch
John Eccles
Arthur Stanley Eddington
Paul Ehrenfest
Albert Einstein
Hugh Everett, III
Franz Exner
Richard Feynman
R. A. Fisher
Joseph Fourier
Lila Gatlin
Michael Gazzaniga
GianCarlo Ghirardi
J. Willard Gibbs
Nicolas Gisin
Paul Glimcher
Thomas Gold
A.O.Gomes
Brian Goodwin
Joshua Greene
Jacques Hadamard
Patrick Haggard
Stuart Hameroff
Augustin Hamon
Sam Harris
Hyman Hartman
John-Dylan Haynes
Martin Heisenberg
Werner Heisenberg
John Herschel
Jesper Hoffmeyer
E. T. Jaynes
William Stanley Jevons
Roman Jakobson
Pascual Jordan
Ruth E. Kastner
Stuart Kauffman
Simon Kochen
Stephen Kosslyn
Ladislav Kovàč
Rolf Landauer
Alfred Landé
Pierre-Simon Laplace
David Layzer
Benjamin Libet
Seth Lloyd
Hendrik Lorentz
Josef Loschmidt
Ernst Mach
Donald MacKay
Henry Margenau
James Clerk Maxwell
Ernst Mayr
Ulrich Mohrhoff
Jacques Monod
Emmy Noether
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
Juan Roederer
Jerome Rothstein
David Ruelle
Erwin Schrödinger
Aaron Schurger
Claude Shannon
David Shiang
Herbert Simon
Dean Keith Simonton
B. F. Skinner
Roger Sperry
Henry Stapp
Tom Stonier
Antoine Suarez
Leo Szilard
William Thomson (Kelvin)
Peter Tse
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
H. Dieter Zeh
Ernst Zermelo
Wojciech Zurek

Presentations

Biosemiotics
Free Will
Mental Causation
James Symposium
 
David Lewis
The analytic language philosopher David Lewis was a possibilist. He developed the philosophical methodology known as modal realism based on the idea of possible worlds. He claims that
  • Possible worlds exist and are just as real as our world.
  • Possible worlds are the same sort of things as our world – they differ in content, not in kind.
  • Possible worlds cannot be reduced to something more basic – they are irreducible entities in their own right.
  • Actuality is indexical. When we distinguish our world from other possible worlds by claiming that it alone is actual, we mean only that it is our world.
  • Possible worlds are unified by the spatiotemporal interrelations of their parts; every world is spatiotemporally isolated from every other world.
  • Possible worlds are causally isolated from each other.

Possible Worlds Without Possibilitiesl
Modal realism implies the existence of infinitely many parallel universes, an idea similar to Hugh Everett III's many-worlds interpretation of quantum mechanics. In the information interpretation of quantum mechanics, quantum systems evolve in two ways: the first is the wave function deterministically exploring all the possibilities for interaction; the second is the particle randomly choosing one of those possibilities to become actual.

But David Lewis is a materialist and determinist who believes that our world, the actual world, could not have been otherwise. Thus, Lewis is not a true possibilist. He insists that all his possible worlds are real and actual (cf. Hegel's "the real is the actual"). In each of Lewis's possible worlds, there are no possibilities other than the completely determined actualities.
All of David Lewis's possible worlds are actual worlds!

There are no real possibilities in any of David Lewis's possible worlds. For information philosophy, possibilities are of course not real in the sense of actual, but are realized when they are actualized. Possibilities have the same existential or ontological status as ideas, especially multiple ideas in a mind that are evaluated as .alternative possibilities for action.

Possible worlds and modal reasoning made "counterfactual" arguments extremely popular in current philosophy. Possible worlds, especially the idea of "nearby worlds" that differ only slightly from the actual world, are used to examine the validity of modal notions such as necessity and contingency, possibility and impossibility, truth and falsity.

But counterfactuals and Lewis's counterpart theory are just language games, ways of talking, that analytic language philosophers and metaphysicians have found productive. They do have an ontological commitment to possibilities or ideas.

Lewis appears to have believed that the truth of his counterfactuals was a result of believing that for every non-contradictory statement there is a possible world in which that statement is true.

  • True propositions are those that are true in the actual world.
  • False propositions are those that are false in the actual world.
  • Necessarily true propositions are those that are true in all possible worlds.
  • Contingent propositions are those that are true in some possible worlds and false in others.
  • Possible propositions are those that are true in at least one possible world.
  • Impossible propositions are those that are true in no possible world .

Possible Worlds, Evil, and Free Will
In his essay, Evil for Freedom's Sake, Lewis was interested in the problem of evil as something that could be analyzed in terms of possible worlds. He examined compatibilism and incompatibilism.
Adequate determination by our character, reasons, motives, is NOT predetermination from before we make our decisions
Compatibilism says that our choices are free insofar as they manifest our characters (our beliefs, desires, etc.) and are not determined via causal chains that bypass our characters. If so, freedom is compatible with predetermination of our choices via our characters. The best argument for compatibilism is that we know better that we are sometimes free than that we ever escape predetermination; wherefore it may be for all we know that we are free but predetermined.

This is a misinterpretation of indeterminism as a factor in the two-stage model of free will
Incompatibilism says that our choices are free only if they have no determining causes outside our characters - not even causes that determine our choices via our characters. The best argument for incompatibilism rests on a plausible principle that unfreedom is closed under implication.

Consider the prefix 'it is true that, and such-and-such agent never had any choice about whether', abbreviated 'Unfree'; suppose we have some premises (zero or more) that imply a conclusion; prefix 'Unfree' to each premise and to the conclusion; then the closure principle says that the prefixed premises imply the prefixed conclusion. Given determinism, apply closure to the implication that takes us from preconditions outside character - long ago, perhaps - and deterministic laws of nature to the predetermined choice. Conclude that the choice is unfree. Compatibilists must reject the closure principle. Let's assume that incompatibilists accept it. Else why are they incompatibilists? I'll speak of compatibilist freedom' and 'incompatibilist freedom'. But I don't ask you to presuppose that these are two varieties of freedom. According to incompatibilism, compatibilist freedom is no more freedom than counterfeit money is money.

It seems that free-will theodicy must presuppose incompatibilism. God could determine our choices via our characters, thereby preventing evil-doing while leaving our compatibilist freedom intact. Thus He could create utopia, a world where free creatures never do evil.

Plantinga once responded to compatibilist opponents as if their objection were a terminological quibble. The hypothesis is that God permits evil so that our actions may be not determined. If you find 'free' a tendentious word, use another word: 'unfettered', say. But of course the issue is one of value, not terminology. The opponents grant the value of compatibilist freedom. But they think that if God permits evil for the sake of incompatibilist freedom, what He gains is worthless.

There are no real possibilities in any of David Lewis's possible worlds.
Yet for purposes of mere 'defence' it needn't be true, or even plausible, that incompatibilist freedom has value. It is enough that it be possible. Plantinga's short way with the compatibilists would have been fair if, but only if, it was common ground that a false and implausible value judgement is nevertheless possible.

Before we turn back to the free-will theodicy that does presuppose incompatibilism, let's consider the compatibilist alternative a little further. Suppose God did determine our choices via our characters, preventing evil-doing while leaving us free.

Lewis is a materialist and determinist who believes the world is causally closed under the laws of nature.
How might He do it? By a wise choice of initial conditions and uniform, powerful, simple laws of nature? - That might be mathematically impossible. The problem might be overconstrained. It might be like the problem: find a curve which is given by an equation no more than fifteen characters long, and which passes through none of the following hundred listed regions of the plane.

Many philosophers criticize the idea of "gaps" in the laws of nature, some equating it with ontological chance
Rather, God might attain utopia by elaborate contrivance; Instead of uniform and powerful laws of nature, He could leave the laws gappy, leaving Him room to intervene directly in the lives of His creatures and guide them constantly back to the right path. Or (if indeed this is possible) His laws might be full of special quirks designed to apply only to very special cases. Either way, despite our compatibilist freedom, God would be managing our lives in great detail, making extensive use of His knowledge and power.
In a 1981 article in Theoria, David Lewis said that van Inwagen's Consequence Argument fails as a reductio ad absurdum argument. Van Inwagen agreed and called Lewis' article “the finest essay that has ever been written in defense of compatibilism – possibly the finest essay that has ever been written about any aspect of the free will problem”. ("How to Think about the Problem of Free Will”, Journal of Ethics (2008) 12, 337-341).

Kadri Vihvelin has written a critical analysis of van Inwagen and Lewis's reply. She says "The Consequence Argument was supposed to show that if we attribute ordinary abilities to deterministic agents, we are forced to credit them with incredible past or law-changing abilities as well. But no such incredible conclusion follows. All that follows is something that we must accept anyway, as the price of our non-godlike nature: that the exercise of our abilities depends partly on circumstances outside our control." Vihveilin thinks humans have "finite minds," which is the idea of impossibilism.

Temporal Parts
Besides his extravagant and outlandish (literally!) invention of infinite possible worlds, Lewis also exploded our actual world into an infinity of "temporal parts," with properties he calls "temporary intrinsics."

In his analysis of the metaphysical problem of the persistence of objects, the question of their identity over time, Lewis proposes the idea of temporal parts. He calls his solution "perdurance," which he distinguishes from "endurance," which he says is different from ordinary persistence, but this difference is not made clear.

Lewis says:

Our question of overlap of worlds parallels the this-worldly problem of identity through time; and our problem of accidental intrinsics parallels a problem of temporary intrinsics, which is the traditional problem of change. Let us say that something persists iff, somehow or other, it exists at various times; this is the neutral word.
The road parts do not exactly persist. They are intrinsically different parts. The enduring entity does persist simpliciter. There is zero evidence of a discontinuous process that produces a disappearance and reappearance. It would violate physical conservation laws
Something perdures iff it persists by having different temporal parts, or stages, at different times. though no one part of it is wholly present at more than one time; whereas it endures iff it persists by being wholly present at more than one time. Perdurance corresponds to the way a road persists through space; part of it is here and part of it is there, and no part is wholly present at two different places. Endurance corresponds to the way a universal, if there are such things, would be wholly present wherever and whenever it is instantiated. Endurance involves overlap: the content of two different times has the enduring thing as a common part. Perdurance does not.

This is a variation of an Academic Skeptic argument about growth, that even the smallest material change destroys an entity and another entity appears. There is no physical or metaphysical reason for this wild assumption. Nevertheless, Lewis's "counterfactual" thinking is highly popular among modern metaphysicians. .

Note that the modern defender of "modally real" possible worlds is a determinist who does not believe that alternative possibilities are real. Ironically, Lewis is an actualist, in every "possible" world.

References
Lewis, D. K. (1981). "Are We Free to Break the Laws?," Theoria 47 (1981), 113-121) [PDF]
Lewis, D. K. (1986). On the plurality of worlds. Oxford: Blackwell.

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