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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
John Herschel
Werner Heisenberg
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
 
Ulrich Mohrhoff

Ulrich Mohrhoff trained as a physicist in Göttingen and at the Indian Institute of Science in Bangalore. He does research in the foundations of physics and looks for connections between quantum physics and Indian philosophy/psychology, especially the Vedas and Upanishads. He has investigated the "free-will problem" from the standpoint of interactions between mind and body, and formulated a new interpretation of quantum mechanics that he calls the Pondicherry Interpretation.

In his 1999 article, "The Physics of Interactionism," Mohrhoff investigated "another hard problem" (beyond David Chalmers's consciousness), namely "how anything material can have freedom." He says:

Denying randomness is the second part of the standard argument against free will
By 'freedom' I mean a person's ability to behave in a purposive, non-random fashion that is not determined by neurophysiological structure and physical law. I do not mean the absence of other determining factors, as this would render freedom synonymous with randomness...

Physics has been invoked both to refute and to support psycho-physical interactionism, the view that mind and matter are two mutually irreducible, interacting domains. Thus it has been held against interactionism that it implies violations of the laws of physics, notably the law of energy conservation. I examine the meaning of conservation laws in physics and show that in fact no valid argument against the interactionist theory can be drawn from them. In defence of interactionism it has been argued that mind can act on matter through an apparent loophole in physical determinism, without violating physical laws. I show that this argument is equally fallacious.

This leads to the conclusion that the indeterminism of quantum mechanics cannot be the physical correlate of free will; if there is a causally efficacious non-material mind, then the behaviour of matter cannot be fully governed by physical laws. I show that the best (if not the only) way of formulating departures from the 'normal', physically determined behaviour of matter is in terms of modifications of the electromagnetic interactions between particles. I also show that mental states and events are non-spatial, and that departures from the 'normal' behaviour of matter, when caused by mental events, are not amenable to mathematical description.

Today we see "determinism" as an abstract idea that emerges from the chaotic microcosmos.
Mohrhoff examines the possibility of a "causal primary," an antecedent cause that is not itself caused. This is the classical causa sui, the "uncaused cause" of Aristotle and others. Indeterministic quantum events have been the leading candidate for such causes since Arthur Stanley Eddington's 1927 book The Nature of the Physical World announced the demise of determinism. He says:

The absence of causal primaries is often called 'the causal closure of the physical world', where 'physical' means 'non-mental' rather than 'governed by the laws of physics'.
Causal closure is used by Jaegwon Kim to deny downward causation and the possibility of a non-reductive physicalism.
This causal closure is a trivial consequence of the lack of scientific interest which results from being unable to identify causal primaries. What is causally closed is the scientifically known world, not the world as such. Yet there are many philosophers who look upon causal closure as an ontological truth and go on to invoke it as an argument against interactionism, the doctrine that mind and matter are two mutually irreducible, interacting spheres. Interactionists as I understand them are motivated primarily by a desire to make room for free will, the denial of which is both counterintuitive and at odds with notions (moral and otherwise) that are central to the fabric of our active lives. While repudiating the causal closure of the physical world, interactionists nevertheless shrink from contesting the validity of the laws of physics, not realizing that this is contingent on the presumption of causal closure.

Quantum-mechanical indeterminism is not a "loophole" but an irreducible component
of standard quantum physics.
It is difficult to integrate into interactionism because it threatens to make actions random, as Mohrhoff notes.
That is how we come to witness futile fights between philosophers of mind who reject interactionism on the ground that it is incompatible with the laws of physics and, in particular, the law of the conservation of energy, and interactionists who meekly defend their position, claiming that, by exploiting the loophole of quantum-mechanical indeterminism, non-material mind is capable of influencing matter without violating conservation laws. Both the charge and the defence are misconceived. The law of energy conservation is either true by virtue of the meaning of 'energy', and therefore is not threatened by interactionism, or it is contingent upon the causal closure of the physical world, and therefore is no threat to interactionism. The loophole hypothesis, on the other hand, violates basic physical laws other than the law of energy conservation.

If causal primaries "freely" generate new (non-material) ideas in the mind, and if an adequately determined "will" follows one idea by moving the body, such an interaction violates no physical law.
This should not come as a surprise. To be causally efficacious, mental events that are causal primaries must make a difference to the behaviour of matter and thus to the behaviour of its constituent particles. The effects of such events on the behaviour of particles have to be expressed in the language of physics, for this is the only language suitable for describing the behaviour of particles. But the laws of physics presuppose causal closure and describe the behaviour of matter in the absence of causal primaries. Hence it follows that the behaviour of matter in the presence of a causally efficacious non-material mind cannot be fully governed by those laws.

Mohrhoff attempts to show that mind is "not spatial" and that makes it not amenable to a mathematical description (for example, one describable in terms of electromagnetic fields with conservation of energy and momentum). He reaches the following conclusions:

(1) The conservation of energy and momentum is a consequence of the homogeneity of time and of space. This is warranted for systems that are causally closed. As to material systems that are open to causal influences from non-material mind, either energy/momentum is/are ill-defined or there is no reason why it/they should be conserved.

(2) Assuming that part but not all of matter is causally open to non-material mind, it makes sense to attribute (non-conserved) energy and momentum even to physical systems that interact with non-material mind.

(3) The causal efficacy of non-material mind implies departures from the statistical laws of quantum physics. These departures are capable of being formulated in terms of modifications, by the conscious self, of the electromagnetic interactions between particles; and they are more consistently formulated in this manner.

(4) Because the electromagnetic field is a summary representation of effects on the motion of particles, the effects caused by mental events are necessarily among the effects represented by it. It is not that one cannot formulate the effects of the self in terms of a separate probability field, to use Margenau's (1984) term. The point is that this field would be indistinguishable from a contribution to the electromagnetic field, which makes it obvious that departures from the laws of physics are involved. Thinking of the effects of the self as contributions to the electromagnetic field is preferable for two reasons. First, it eschews the contentious notion that measurement-like events take place in the unobserved brain. Second, it leads to a more unified treatment of causality. There is no reason whatever for having probabilities determined twice over, once during their deterministic evolution by the physically determined vector potential, and once at the end through a superimposed probability field generated by the self.

(5) Quantum-mechanical indeterminism cannot be the physical correlate of free will. Free will implies departures from the laws of physics.

(6) Mind is non-spatial. There is no point in attributing positions to mental states and events.

(7) The departures from the physical laws caused by non-physical mental events are not amenable to mathematical description. It is worth emphasizing that they are not therefore random. They could be necessitated by something of a primarily qualitative nature, something that manifests itself in quantitative, spatio-temporal terms but is not reducible to these terms.

The Pondicherry Interpretation of Quantum Mechanics
Mohrhoff has formulated an ambitious interpretation of quantum mechanics. His interpretation:
...proceeds from the recognition that the fundamental theoretical framework of physics is a probability algorithm, which serves to describe an objective fuzziness (the literal meaning of Heisenberg's term 'Unschärfe', usually mistranslated as 'uncertainty') by assigning objective probabilities to the possible outcomes of unperformed measurements. Although it rejects attempts to construe quantum states as evolving ontological states, it arrives at an objective description of the quantum world that owes nothing to observers or the goings-on in physics laboratories. In fact, unless such attempts are rejected, quantum theory's true ontological implications cannot be seen.
Mohrhoff says the role of the "observer" is a source of confusion and that wave functions do not provide only "subjective" knowledge. Quantum mechanics is not epistemology, despite the attempts of many "interpreters" to make it so, it provides our best "objective" ontology. There are facts about the quantum world.
Quantum mechanics gives us probability amplitudes, of course. Probabilities, being always positive, cannot interfere with one another
Quantum mechanics, the fundamental theoretical framework of contemporary physics, is a probability algorithm. This serves to assign, on the basis of outcomes of measurements that have been made, probabilities to the possible outcomes of measurements that may be made. The inevitable reference to 'measurement' in all standard axiomatizations of unadulterated quantum mechanics was famously criticized by John Bell: "To restrict quantum mechanics to be exclusively about piddling laboratory operations is to betray the great enterprise." The search for more respectable ways of thinking about measurements began early. Since the discovery of special relativity in 1905, physicists had become used to calling them 'observations', and in 1939 London and Bauer [16] were the first to speak of 'the essential role played by the consciousness of the observer'.

Over the years, this red herring has taken many forms. To a few [Wigner], it meant that the mind of the observer actively intervenes in the goings-on in the physical world, to some (e.g. [D'Espagnat]), it meant that science concerns our perceptions rather than the goings-on 'out there', while to most (e.g. [Fuchs, Peres, Petersen, Peierls]), it meant that quantum mechanics concerns knowledge or information about the physical world, rather than the physical world itself.

It is not hard to account for the relative popularity of the slogan 'quantum states are states of knowledge' [Fuchs on decoherence]. The fundamental theory of the physical world is a probability algorithm, and there is a notion that probabilities are inherently subjective. Subjective probabilities are ignorance probabilities: they enter the picture when relevant facts are ignored. Because we lack the information needed to predict on which side a coin will fall, we assign a probability to each possibility. Subjective probabilities disappear when all relevant facts are taken into account (which in many cases is practically impossible).

The notion that probabilities are inherently subjective is a wholly classical idea. The very fact that our fundamental physical theory is a probability algorithm tells us that the probabilities it serves to assign are objective. The existence of objective probabilities (not to be confused with relative frequencies) is due to the fact that even the totality of previous measurement outcomes is insufficient for predicting subsequent measurement outcomes with certainty. The 'uncertainty principle' (the literal meaning of Heisenberg's original term, fuzziness principle, is more to the point), guarantees that, unlike subjective probabilities, quantum mechanical probabilities cannot be made to disappear. If the relevant facts are sufficient to predict a position with certainty, there are no facts that would allow us to predict the corresponding momentum. What matters are facts, not what we can know about them.

The Mohrhoff-Stapp Debate
Ulrich Mohrhoff reacted to Henry Stapp's 2001 article "Quantum Theory and the Role of Mind in Nature with the claim that it contained 18 errors, primarily the result of misunderstandings or misinterpretations of standard quantum mechanics and its application to mental causation. (See "Mohrhoff on Stapp.") Stapp was generous in answering Mohrhoff's biting criticism with a fine sense of humor. He takes Mohrhoff's 18 error claims as generating a Buddhist "18-fold way" which result in 18 questions with 18 possible right (Yes/No) answers. Stapp worries that he has only one chance in 250,000 of getting the answers all right (2-18). (See "Stapp on Mohrhoff.")

Then take a look at our critical comparison of their questions and answers. See "The Mohrhoff-Stapp Debate."

Works
The World According to Quantum Mechanics: Why the Laws of Physics Make Perfect Sense After All (2011)

Objective probability and quantum fuzziness 2009 (PDF)

Quantum Mechanics Explained 2006 (PDF)

Pondicherry Interpretation of Quantum Mechanics 2005 (PDF)

This Quantum World - Mohrhoff's website/blog

Mohrhoff's Papers and Presentations

Quantum Theory and the Role of Mind in Nature

The World According to Quantum Mechanics (Or, the 18 Errors of Henry P. Stapp) (Mohrhoff on Stapp)

The 18-Fold Way (Stapp on Mohrhoff)

For Scholars

Chapter 1.5 - The Philosophers Chapter 2.1 - The Problem of Knowledge
Home Part Two - Knowledge
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