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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
Daniel Boyd
F.H.Bradley
C.D.Broad
Michael Burke
Lawrence Cahoone
C.A.Campbell
Joseph Keim Campbell
Rudolf Carnap
Carneades
Nancy Cartwright
Gregg Caruso
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
Austin Farrer
Herbert Feigl
Arthur Fine
John Martin Fischer
Frederic Fitch
Owen Flanagan
Luciano Floridi
Philippa Foot
Alfred Fouilleé
Harry Frankfurt
Richard L. Franklin
Bas van Fraassen
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
R.E.Hobart
Thomas Hobbes
David Hodgson
Shadsworth Hodgson
Baron d'Holbach
Ted Honderich
Pamela Huby
David Hume
Ferenc Huoranszki
Frank Jackson
William James
Lord Kames
Robert Kane
Immanuel Kant
Tomis Kapitan
Walter Kaufmann
Jaegwon Kim
William King
Hilary Kornblith
Christine Korsgaard
Saul Kripke
Thomas Kuhn
Andrea Lavazza
Christoph Lehner
Keith Lehrer
Gottfried Leibniz
Jules Lequyer
Leucippus
Michael Levin
Joseph Levine
George Henry Lewes
C.I.Lewis
David Lewis
Peter Lipton
C. Lloyd Morgan
John Locke
Michael Lockwood
Arthur O. Lovejoy
E. Jonathan Lowe
John R. Lucas
Lucretius
Alasdair MacIntyre
Ruth Barcan Marcus
Tim Maudlin
James Martineau
Nicholas Maxwell
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
Thomas Nagel
Otto Neurath
Friedrich Nietzsche
John Norton
P.H.Nowell-Smith
Robert Nozick
William of Ockham
Timothy O'Connor
Parmenides
David F. Pears
Charles Sanders Peirce
Derk Pereboom
Steven Pinker
Plato
Karl Popper
Porphyry
Huw Price
H.A.Prichard
Protagoras
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
Isabelle Stengers
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
C.F. von Weizsäcker
William Whewell
Alfred North Whitehead
David Widerker
David Wiggins
Bernard Williams
Timothy Williamson
Ludwig Wittgenstein
Susan Wolf

Scientists

David Albert
Michael Arbib
Walter Baade
Bernard Baars
Jeffrey Bada
Leslie Ballentine
Marcello Barbieri
Gregory Bateson
Horace Barlow
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
Jean Bricmont
Hans Briegel
Leon Brillouin
Stephen Brush
Henry Thomas Buckle
S. H. Burbury
Melvin Calvin
Donald Campbell
Sadi Carnot
Anthony Cashmore
Eric Chaisson
Gregory Chaitin
Jean-Pierre Changeux
Rudolf Clausius
Arthur Holly Compton
John Conway
Jerry Coyne
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
Bernard d'Espagnat
Paul Dirac
Hans Driesch
John Eccles
Arthur Stanley Eddington
Gerald Edelman
Paul Ehrenfest
Manfred Eigen
Albert Einstein
George F. R. Ellis
Hugh Everett, III
Franz Exner
Richard Feynman
R. A. Fisher
David Foster
Joseph Fourier
Philipp Frank
Steven Frautschi
Edward Fredkin
Benjamin Gal-Or
Howard Gardner
Lila Gatlin
Michael Gazzaniga
Nicholas Georgescu-Roegen
GianCarlo Ghirardi
J. Willard Gibbs
James J. Gibson
Nicolas Gisin
Paul Glimcher
Thomas Gold
A. O. Gomes
Brian Goodwin
Joshua Greene
Dirk ter Haar
Jacques Hadamard
Mark Hadley
Patrick Haggard
J. B. S. Haldane
Stuart Hameroff
Augustin Hamon
Sam Harris
Ralph Hartley
Hyman Hartman
Jeff Hawkins
John-Dylan Haynes
Donald Hebb
Martin Heisenberg
Werner Heisenberg
John Herschel
Basil Hiley
Art Hobson
Jesper Hoffmeyer
Don Howard
John H. Jackson
William Stanley Jevons
Roman Jakobson
E. T. Jaynes
Pascual Jordan
Eric Kandel
Ruth E. Kastner
Stuart Kauffman
Martin J. Klein
William R. Klemm
Christof Koch
Simon Kochen
Hans Kornhuber
Stephen Kosslyn
Daniel Koshland
Ladislav Kovàč
Leopold Kronecker
Rolf Landauer
Alfred Landé
Pierre-Simon Laplace
Karl Lashley
David Layzer
Joseph LeDoux
Gerald Lettvin
Gilbert Lewis
Benjamin Libet
David Lindley
Seth Lloyd
Hendrik Lorentz
Werner Loewenstein
Josef Loschmidt
Ernst Mach
Donald MacKay
Henry Margenau
Owen Maroney
David Marr
Humberto Maturana
James Clerk Maxwell
Ernst Mayr
John McCarthy
Warren McCulloch
N. David Mermin
George Miller
Stanley Miller
Ulrich Mohrhoff
Jacques Monod
Vernon Mountcastle
Emmy Noether
Donald Norman
Alexander Oparin
Abraham Pais
Howard Pattee
Wolfgang Pauli
Massimo Pauri
Wilder Penfield
Roger Penrose
Steven Pinker
Colin Pittendrigh
Walter Pitts
Max Planck
Susan Pockett
Henri Poincaré
Daniel Pollen
Ilya Prigogine
Hans Primas
Zenon Pylyshyn
Henry Quastler
Adolphe Quételet
Pasco Rakic
Nicolas Rashevsky
Lord Rayleigh
Frederick Reif
Jürgen Renn
Giacomo Rizzolati
Emil Roduner
Juan Roederer
Jerome Rothstein
David Ruelle
David Rumelhart
Tilman Sauer
Ferdinand de Saussure
Jürgen Schmidhuber
Erwin Schrödinger
Aaron Schurger
Sebastian Seung
Thomas Sebeok
Franco Selleri
Claude Shannon
Charles Sherrington
David Shiang
Abner Shimony
Herbert Simon
Dean Keith Simonton
Edmund Sinnott
B. F. Skinner
Lee Smolin
Ray Solomonoff
Roger Sperry
John Stachel
Henry Stapp
Tom Stonier
Antoine Suarez
Leo Szilard
Max Tegmark
Teilhard de Chardin
Libb Thims
William Thomson (Kelvin)
Richard Tolman
Giulio Tononi
Peter Tse
Alan Turing
Francisco Varela
Vlatko Vedral
Mikhail Volkenstein
Heinz von Foerster
Richard von Mises
John von Neumann
Jakob von Uexküll
C. S. Unnikrishnan
C. H. Waddington
John B. Watson
Daniel Wegner
Steven Weinberg
Paul A. Weiss
Herman Weyl
John Wheeler
Wilhelm Wien
Norbert Wiener
Eugene Wigner
E. O. Wilson
Günther Witzany
Stephen Wolfram
H. Dieter Zeh
Semir Zeki
Ernst Zermelo
Wojciech Zurek
Konrad Zuse
Fritz Zwicky

Presentations

Biosemiotics
Free Will
Mental Causation
James Symposium
 
John R. Lucas

Lucas is perhaps best known for his 1959 article "Minds. Machines, and Gödel," which led to a debate with Douglas Hofstadter, whose "Gödel, Escher, Bach" includes a strong criticism of Lucas and defense of the idea of artificial intelligent machines.
Gödel's theorem seems to me to prove that Mechanism is false, that is, that minds cannot be explained as machines. So also has it seemed to many other people: almost every mathematical logician I have put the matter to has confessed to similar thoughts, but has felt reluctant to commit himself definitely until he could see the whole argument set out, with all objections fully stated and properly met. This I attempt to do.

Gödel's theorem states that in any consistent system which is strong enough to produce simple arithmetic there are formulae which cannot be proved-in-the-system, but which we can see to be true. Essentially, we consider the formula which says, in effect, "This formula is unprovable-in-the-system". If this formula were provable-in-the-system, we should have a contradiction: for if it were provablein-the-system, then it would not be unprovable-in-the-system, so that "This formula is unprovable-in-the-system" would be false: equally, if it were provable-in-the-system, then it would not be false, but would be true, since in any consistent system nothing false can be provedin-the-system, but only truths. So the formula "This formula is unprovable-in-the-system" is not provable-in-the-system, but unprovablein-the-system. Further, if the formula "This formula is unprovablein-the-system" is unprovable-in-the-system, then it is true that that formula is unprovable-in-the-system, that is, "This formula is unprovable-in-the-system" is true.

Gödel's theorem must apply to cybernetical machines, because it is of the essence of being a machine, that it should be a concrete instantiation of a formal system. It follows that given any machine which is consistent and capable of doing simple arithmetic, there is a formula which it is incapable of producing as being true---i.e., the formula is unprovable-in-the-system-but which we can see to be true. It follows that no machine can be a complete or adequate model of the mind, that minds are essentially different from machines.

In 1970, Lucas published The Freedom of the Will, which uses quantum uncertainty and the mathematical uncertainty in Gödel's theorem to attack deterministic and compatibilist accounts and to defend freedom of the will. Of course the indeterminism of quantum chance only provides the proof against determinism. It does not explain the adequate determinism of the second stage of our free will model that explains moral responsibility, which Lucas defended in his important 1995 book Responsibility.
The three great problems of philosophy, according to Kant, 1- are God, freedom, and immortality. Of these, freedom, that is, the Freedom of the Will, is the one most accessible to reason, and has continued to perplex us to the present day. We have a profound conviction of freedom. We know we are free. Yet when we think of ourselves from a scientific point of view, we do not see how we can be free. It would be a denial of science, we feel, to make man an exception to the universal laws of nature, and say that although everything else could be explained in terms of cause and effect, men were different, and were mysteriously exempt from the sway of natural laws. Men, scientifically speaking, are no different from anything else. There is no special privilege of humanity, so far as science is concerned, which makes human behaviour not susceptible of scientific enquiry and scientific explanation. There must be causes of human behaviour, as there are causes of everything else. To think otherwise is pure superstition. For there is no evidence to the contrary, and already physiologists, neurologists, and psychologists have been remarkably successful in explaining human behaviour. To maintain a doctrine of freedom in the face of these facts is mere anthropomorphic obscurantism. And yet we are reluctant to surrender our freedom without a struggle. The doctrine that we are not free runs counter to something we know to be true so surely that only the most irrefragable arguments could shake the intimations of our everyday experience. Moreover, if we did abandon our belief in freedom, we should have to abandon much else in our view of ourselves and of our moral and rational life. Nor is it clear that we ought not to think anthropomorphically. After all, we are men: we do regard men, ourselves and others, as being different from the rest of creation. Men are rational, and ought to be treated not merely as means, but always also as ends. We condemn the nazis for regarding non-Aryan men as mere animals, and treating them scientifically, as mere objects of scientific research. We are entitled at least to put the case against freedom to the test. The claim needs to be stated with precision, and the arguments expressed in full, and counter-arguments considered. Much depends on the conclusion. If it be superstition to believe in freedom, and we conclude in favour of freedom, we shall be committed to superstition. 2 If, on the other hand, we conclude that man is not free, we may have to revise many of our present concepts about man and morality, responsibility and punishment, history and humanity. Kant was right in thinking freedom to be an unavoidable problem set by pure reason, though wrong in despairing of the power of reason to solve it. For the very fact that freedom is a problem for reason is itself a reason for believing that we are free. Many men have sensed this, but the argument is extremely difficult to articulate and assess. I have attempted to articulate it in Section 21, and in the following sections to reformulate it in formal terms with the aid of a profound theorem of mathematical logic discovered by Godel in 1929. It is a controversial argument, and I have tried to meet objections raised against it, for I believe it to be ultimately a decisive argument which will refute the one sort of determinism—physical determinism—which seriously worries men today. But it is not the only argument, and its bearing is difficult to assess except in the context of the whole debate; and in the first two thirds of the book I discuss, in a more orthodox fashion, the main points at issue, to which innumerable men have contributed many arguments in many forms. I have not tried to do justice to them. Exhaustive treatments are exhausting. Moreover, philosophy has to be self-thought if it is to be thought at all. It is an activity, rather than a set of propositions. Each man needs to think out the problems and their solutions for himself, and although other men's philosophizing may help him in his own, he cannot accept their conclusions, or even understand their arguments, until he has already argued a lot with himself. I have aimed to be, so far as one can be, unsophisticated. The footnotes are intended to supply the deficiency, and show the reader where he can follow up any particular line of argument in greater detail and with greater subtlety. Although I think some conclusions can be reasonably well established, I do not offer any formal proofs, but only, I hope, show how one may think one's way through to these conclusions for oneself. But only the reader, not I, can carry the programme through.
In 1992, Lucas looked back at the efforts of C. S. Lewis fifty years earlier to attack the scientific view of man and restore a "moral objectivism," which had come under attack by philosophers, who argued that morals were subjective and relative to cultures. Lewis had attacked the superficial "selective skepticism" being taught to students, who were then ready to debunk traditional values, but not the values inculcated by their sophisticated philosophy professors. Lewis, says Lucas, opposed what he saw as the "thorough-going rejection of all moral judgment." In the United States, this was the theme of B. F. Skinner's behavioral psychology, soon to become "cognitive science."
Lewis has two lines of argument. One, which recurs in his novels and in his inaugural lecture at Cambridge, is that we destroy man's humanity if we treat him merely as a means, and not also as an autonomous, rational, end in himself. Emancipated from the shackles of morality, a man will treat other men merely as things, manipulating them to serve his own ends. Lewis was particularly afraid of genetic engineering, and in this, again, he was prescient. We might take issue with him on some points. Not all genetic counselling and therapy need be manipulative. And some measure of control is not the same as complete control. We always have had some measure of control over future generations---the monks of Durham were able to secure that no sons of theirs would ever sin. What frightened Lewis, and ought to frighten us, is the possibility that, by genetic engineering or social conditioning, we could program people to behave exactly as we pleased. For then they would not be people, beings other than ourselves with a mind of their own, but merely artefacts---things we could use, but not persons we could communicate with, share with, identify with, or care about.

Lewis's second argument concerns the manipulators rather than those manipulated. Emancipation for them is liberation into a vacuum. If everything is permitted, nothing is worthwhile. The Conditioners, who have no scruples to prevent them manipulating and refashioning man to their own liking, have no grounds for liking any one thing rather than any other. For a time, Lewis thinks, they may be guided by vestiges of objective values not yet completely dethroned, but in the end they can have no rational motives to guide them in deciding how to fashion subsequent generations. The same sense of human worth which ought to restrain them from manipulating other men merely as means to their own purposes provides the purposes that alone make our goals worthwhile and our decisions meaningful. In liberating ourselves from the tie of obligation to others, we diminish ourselves too, and deprive ourselves of any standards of achievement by reference to which we could hope to have done well. We are no longer rational agents, but. like other men, the playthings of heredity and environment, instinct and social conditioning.

Articles by J. R. Lucas
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