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Philosophers

Mortimer Adler
Rogers Albritton
Alexander of Aphrodisias
Samuel Alexander
G.E.M.Anscombe
Anselm
Louise Antony
Thomas Aquinas
Aristotle
David Armstrong
Harald Atmanspacher
Augustine
J.L.Austin
A.J.Ayer
Alexander Bain
Mark Balaguer
Jeffrey Barrett
William Belsham
Henri Bergson
Isaiah Berlin
Bernard Berofsky
Robert Bishop
Susanne Bobzien
Emil du Bois-Reymond
Hilary Bok
George Boole
Émile Boutroux
F.H.Bradley
C.D.Broad
C.A.Campbell
Joseph Keim Campbell
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
Carl Ginet
Nicholas St. John Green
H.Paul Grice
Ian Hacking
Ishtiyaque Haji
Stuart Hampshire
W.F.R.Hardie
William Hasker
R.M.Hare
Georg W.F. Hegel
Martin Heidegger
R.E.Hobart
Thomas Hobbes
David Hodgson
Shadsworth Hodgson
Ted Honderich
Pamela Huby
David Hume
Ferenc Huoranszki
William James
Lord Kames
Robert Kane
Immanuel Kant
Tomis Kapitan
Jaegwon Kim
William King
Christine Korsgaard
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
James Martineau
Storrs McCall
Hugh McCann
Colin McGinn
Michael McKenna
Brian McLaughlin
Paul E. Meehl
Uwe Meixner
Alfred Mele
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
Huw Price
H.A.Prichard
Hilary Putnam
Willard van Orman Quine
Frank Ramsey
Ayn Rand
Thomas Reid
Charles Renouvier
Nicholas Rescher
C.W.Rietdijk
Richard Rorty
Josiah Royce
Bertrand Russell
Paul Russell
Gilbert Ryle
Kenneth Sayre
T.M.Scanlon
Moritz Schlick
Arthur Schopenhauer
John Searle
Wilfrid Sellars
Henry Sidgwick
Walter Sinnott-Armstrong
J.J.C.Smart
Saul Smilansky
Michael Smith
L. Susan Stebbing
George F. Stout
Galen Strawson
Peter Strawson
Eleonore Stump
Richard Taylor
Kevin Timpe
Mark Twain
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
Ludwig Wittgenstein
Susan Wolf

Scientists

Michael Arbib
Bernard Baars
John S. Bell
Charles Bennett
Ludwig von Bertalanffy
Susan Blackmore
Margaret Boden
David Bohm
Niels Bohr
Ludwig Boltzmann
Emile Borel
Max Born
Walther Bothe
Hans Briegel
Leon Brillouin
Stephen Brush
Henry Thomas Buckle
Donald Campbell
Anthony Cashmore
Eric Chaisson
Jean-Pierre Changeux
Arthur Holly Compton
John Conway
E. H. Culverwell
Charles Darwin
Terrence Deacon
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
Joseph Fourier
Michael Gazzaniga
GianCarlo Ghirardi
Nicolas Gisin
Paul Glimcher
Thomas Gold
A.O.Gomes
Brian Goodwin
Joshua Greene
Jacques Hadamard
Stuart Hameroff
Patrick Haggard
Augustin Hamon
Sam Harris
Martin Heisenberg
Werner Heisenberg
William Stanley Jevons
Pascual Jordan
Simon Kochen
Stephen Kosslyn
Ladislav Kovàč
Rolf Landauer
Alfred Landé
Pierre-Simon Laplace
David Layzer
Benjamin Libet
Hendrik Lorentz
Josef Loschmidt
Ernst Mach
Henry Margenau
James Clerk Maxwell
Ernst Mayr
Ulrich Mohrhoff
Jacques Monod
Wolfgang Pauli
Massimo Pauri
Roger Penrose
Steven Pinker
Max Planck
Susan Pockett
Henri Poincaré
Daniel Pollen
Ilya Prigogine
Hans Primas
Adolphe Quételet
Jerome Rothstein
David Ruelle
Erwin Schrödinger
Aaron Schurger
Claude Shannon
Herbert Simon
Dean Keith Simonton
B. F. Skinner
Roger Sperry
Henry Stapp
Tom Stonier
Antoine Suarez
Leo Szilard
William Thomson (Kelvin)
Peter Tse
John von Neumann
Daniel Wegner
Steven Weinberg
Paul A. Weiss
Norbert Wiener
Eugene Wigner
E. O. Wilson
H. Dieter Zeh
Ernst Zermelo
Wojciech Zurek
 
Benjamin Libet

Benjamin Libet's experiments and measurements of the time before a subject is aware of self-initiated actions have had a enormous, mostly negative, impact on the case for human free will, despite Libet's view that his work does nothing to deny human freedom.

The original discovery that an electrical potential (of just a few microvolts - μV) is visible in the brain long before the subject flexes a finger was made by Kornhuber and Deecke (1964). They called it a "Bereitschaftspotential" or readiness potential.

The neurobiologist John Eccles speculated that the subject must become conscious of the intention to act before the onset of this readiness potential. Benjamin Libet decided to test Eccles's idea.

Libet's 1983 experiments measured the time when the subject became consciously aware of the decision to move the finger. Libet created a dot on the screen of an oscilloscope circulating like the hand of a clock. The subject was asked to note the position of the moving dot when he/she was aware of the conscious decision to move a finger or wrist.

As shown on Kornhuber's RP diagram, Libet found that although conscious awareness of the decision preceded the subject's finger motion by only 200 milliseconds (the red arrow), the rise in the readiness potential was clearly visible at about 550 milliseconds before the flex of the wrist (blue arrow). The subject showed unconscious activity to flex about 350 milliseconds before reporting conscious awareness of the decision to flex. Indeed an earlier slow and very slight rise in the readiness potential can be seen as early as 1.5 seconds before the action.

Libet's results were eagerly adopted by the deniers of free will to indicate that the mind had been made up unconsciously, long before any awareness of "conscious will."

Psychologist Daniel Wegner thinks that conscious will may be just an epiphenomenon, something that is caused by brain events, not the cause of such events. As he put it in his 2002 book The Illusion of Conscious Will,

We don't know what specific unconscious mental processes the RP might represent....The position of conscious will in the time line suggests perhaps that the experience of will is a link in a causal chain leading to action, but in fact it might not even be that. It might just be a loose end — one of those things, like the action, that is caused by prior brain and mental events.

Does the compass steer the ship? In some sense, you could say that it does, because the pilot makes reference to the compass in determining whether adjustments should be made to the ship's course. If it looks as though the ship is headed west into the rocky shore, a calamity can be avoided with a turn north into the harbor. But, of course, the compass does not steer the ship in any physical sense. The needle is just gliding around in the compass housing, doing no actual steering at all. It is thus tempting to relegate the little magnetic pointer to the class of epiphenomena — things that don't really matter in determining where the ship will go.

Conscious will is the mind's compass. As we have seen, the experience of consciously willing action occurs as the result of an interpretive system, a course-sensing mechanism that examines the relations between our thoughts and actions and responds with "I willed this" when the two correspond appropriately. This experience thus serves as a kind of compass, alerting the conscious mind when actions occur that are likely to be the result of one's own agency. The experience of will is therefore an indicator, one of those gauges on the control panel to which we refer as we steer. Like a compass reading, the feeling of doing tells us something about the operation of the ship. But also like a compass reading, this information must be understood as a conscious experience, a candidate for the dreaded "epiphenomenon" label.

Bernard Baars says there are two important time scales of consciousness

Sensory events occurring within a tenth of a second merge into a single conscious sensory experience, suggesting a 100-millisecond scale. But working memory, the domain in which we talk to ourselves or use our visual imagination, stretches out over roughly 10-second steps. The tenth-of-a-second level is automatic, while the 10-second level is shaped by conscious plans and goals.
The kinds of deliberative and evaluative processes that are important for free will involve longer time periods than those studied by Benjamin Libet.

Note also that the abrupt and rapid decisions to flex a finger measured by Libet bear little resemblance to the kinds of two-stage deliberate decisions for which we can first freely generate alternative possibilities for action, then evaluate which is the best of these possibilities in the light of our reasons, motives, and desires - first "free," then "will."

We can correlate the beginnings of the readiness potential (350ms before Libet's conscious will time "W" appears) with the early stage of the two-stage model, when alternative possibilities are being generated, in part at random. The early stage may be delegated to the subconscious, which is capable of considering multiple alternatives (William James' "blooming, buzzing confusion") that would congest the single stream of consciousness.

Alfred Mele has criticized the interpretation of the Libet results on two grounds. First, the mere appearance of the RP a half-second or more before the action in no way makes the RP the cause of the action. It may simply mark the beginning of forming an intention to act. In the two-stage model, it is the considering of possible options.

Libet himself argued that there is enough time after the W moment (a window of opportunity) to veto the action, but Mele's second criticism points out that such examples of "free won't" would not be captured in Libet experiments, because the recording device is triggered by the action (typically flicking the wrist) itself.

Thus, although all Libet experiments ended with the wrist flicking, we are not justified in assuming that the rise of the RP (well before the moment of conscious will) is a cause of the wrist flicking. Libet knew that there were very likely other times when the RP rose, but which did not lead to a flick of the wrist.

Thinkers (e.g., Daniel Wegner, Patrick Haggard) who claim that the Libet experiments prove that our conscious will and subsequent actions are caused by prior neural activity - the popular view that "my neurons made me do it" - are simply wrong.

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