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Mortimer Adler
Rogers Albritton
Alexander of Aphrodisias
Samuel Alexander
William Alston
Louise Antony
Thomas Aquinas
David Armstrong
Harald Atmanspacher
Robert Audi
Alexander Bain
Mark Balaguer
Jeffrey 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
Michael Burke
Joseph Keim Campbell
Rudolf Carnap
Ernst Cassirer
David Chalmers
Roderick Chisholm
Randolph Clarke
Samuel Clarke
Anthony Collins
Antonella Corradini
Diodorus Cronus
Jonathan Dancy
Donald Davidson
Mario De Caro
Daniel Dennett
Jacques Derrida
René Descartes
Richard Double
Fred Dretske
John Dupré
John Earman
Laura Waddell Ekstrom
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
Nicholas St. John Green
H.Paul Grice
Ian Hacking
Ishtiyaque Haji
Stuart Hampshire
Sam Harris
William Hasker
Georg W.F. Hegel
Martin Heidegger
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
Michael Levin
George Henry Lewes
David Lewis
Peter Lipton
C. Lloyd Morgan
John Locke
Michael Lockwood
E. Jonathan Lowe
John R. Lucas
Alasdair MacIntyre
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
Thomas Nagel
Friedrich Nietzsche
John Norton
Robert Nozick
William of Ockham
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David F. Pears
Charles Sanders Peirce
Derk Pereboom
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Thomas Reid
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Richard Rorty
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Bertrand Russell
Paul Russell
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John Searle
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Alan Sidelle
Ted Sider
Henry Sidgwick
Walter Sinnott-Armstrong
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
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Peter van Inwagen
Manuel Vargas
John Venn
Kadri Vihvelin
G.H. von Wright
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R. Jay Wallace
Ted Warfield
Roy Weatherford
William Whewell
Alfred North Whitehead
David Widerker
David Wiggins
Bernard Williams
Timothy Williamson
Ludwig Wittgenstein
Susan Wolf


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
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
Martin J. Klein
Simon Kochen
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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
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Emmy Noether
Abraham Pais
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Wolfgang Pauli
Massimo Pauri
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Steven Pinker
Colin Pittendrigh
Max Planck
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Henri Poincaré
Daniel Pollen
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Hans Primas
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Jerome Rothstein
David Ruelle
Erwin Schrödinger
Aaron Schurger
Claude Shannon
David Shiang
Herbert Simon
Dean Keith Simonton
B. F. Skinner
Roger Sperry
John Stachel
Henry Stapp
Tom Stonier
Antoine Suarez
Leo Szilard
William Thomson (Kelvin)
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
H. Dieter Zeh
Ernst Zermelo
Wojciech Zurek


Free Will
Mental Causation
James Symposium

From Campbell and Garnett, Life of Maxwell,
Whence came we? whither are we going? and what should we do now? are three questions of some celebrity. We have come from somewhere between this and Orion; we are going at — kilometres per second towards Hercules; and we must therefore observe stars in a direction at right angles to our path; — are the answers suggested twenty-five years ago. It seems to me that a change has come over the questions, so that they now read, What used I to believe about myself? what is it likely I shall have to believe about myself? and what should I believe about myself now?

I used to believe myself to be the Conscious Ego. I am told I shall have soon to believe myself to be a congeries of plastidule souls, and that I must at once study psychophysik in order to obtain a true knowledge of myself.

I propose, therefore, to talk of the Conscious Ego, of Plastidule souls, and of Psychophysik.

(1.) [Conscious Ego] What is your name? is a still more celebrated question. The suggested answer, N. or M., recalls to the mathematician ideas and operations of the most heterogeneous kind. Let us consider some of them. The instructors of my youth would have expected me to answer — My name is the Conscious Ego, one and indivisible, the Subject, in relation to whom all other beings, material, human, or divine, are mere Objects. Whether the being of such Objects can be maintained or upheld apart from my continuous perception of them is the great question of Metaphysic.

Though nothing can rise to the dignity even of an Object, except in so far as it is perceived by me, I regard certain Objects as nearer in rank to me, the Subject, than others, because it is through them that other Objects are perceived. Indeed, I often catch myself, when thinking about my body or my mind, supposing that I am thinking about myself.

There are other objects within the sphere of our perceptions which resemble our bodies, though they are not ours. The actions of these objects are so far like our own that we not only attribute to these objects the power of thinking, but also the consciousness of knowing, feeling, desiring and willing. In short, we suppose that each of these objects, when he asserts himself to be the Conscious Ego, means what we do when we make a similar statement.

The late Professor Ferrier, in his 'Metaphysic', makes great use of this Alter Ego, and for his own purposes he treats him as a true Ego, whereas in Metaphysic he can never be more than an Object. This, however, is only a confusion of persons, not an actual division of the substance of the Ego. Our business to-night lies in the abysmal depths of Personality, and relates to the Unity of the Ego.

A great deal of what has been written on this subject relates to the continuity of the Ego in space and time, or in what corresponds in metaphysic to the space and time of physic. And first of Space. Has the Ego anything corresponding to Extension? Has he parts? and, if so, are these parts separable in fact or even in idea? It has been maintained that he has no parts; that his state of consciousness at any instant is an inseparable whole, comparable, in respect of extension, to a mathematical point. According to this view, when I think I see an extensive prospect all at once before me, I am in reality either actually rolling my eye in an unconscious frenzy, or without any bodily motion I, – that is, the perceptive Ego, – am attending first to one minimum visible, and then to another, so that what is presented to me is like the idea which a blind man forms of the shape of an object by stroking it with the end of his stick. The evidence relates only to the position of points in the line traced by the end of his stick, but he fills in the rest of the surface in accordance with his notions of continuity and probability.

There is no department of psychophysik which has been so successfully studied as that which relates to vision. When we keep not only our eyes, but our attention, fixed on one small object, the field of conscious vision seems to contract, till only that object remains visible, and even it seems about to disappear. It generally happens, however, that the feeling of uneasiness which grows upon us causes at last a slight displacement of the eye, when suddenly a large extent of the field starts into visibility, and the edges of objects, especially those normal to the line of displacement, become obtrusively prominent. This experiment seems at first sight to indicate that the central spot of the retina has some exclusive privilege in the economy of vision. What it really shows is that changes in the mode of excitation are essential to perfect vision, and that vision cannot be maintained under an absolute sameness of excitation. On the other hand, by means of the instantaneous light of a single electric spark, we may read a whole sentence of print. Here we know that though the illumination lasts only for a few millionths of a second, the image on the retina lasts for a time amply sufficient for an expert reader to go over it letter by letter, and even to detect misprints. This experiment suggests certain speculations about memory, a faculty which is often supposed to be essential to the continuity of the Ego in time.

When men wish to have things remembered, they set up monuments, and write inscriptions and books, — they draw pictures and take photographs, — in order that these material things may help them, in time to come, to call up the thought of that which they were intended to commemorate.

In our own bodies we have records of past events. Old wounds may remind us of impressions made years ago, and ocular spectra remind us of impressions made seconds ago. Even in quiet meditation we sometimes find the ideas of visible objects accompanied with sensations hardly less vivid than those produced by real objects, and the memory of spoken words passes in a continuous manner, as the condition of our nerves becomes more exalted, first into a silent straining of the organs of speech, and then into an audible voice. Beginners in music may practise on a dumb piano, and there is a silent process by which we may improve our pronunciation of foreign words.

We can thus trace a continuous series of the instruments of memory, beginning at the tables of stone and going on to the tables of the heart; and we are tempted to ask whether all memorials are not of the same kind — a physical impression on a material system.

The last American invention of the past year is Edison's Talking Phonograph. This instrument has an ear of its own, into which you may say your lesson, and a mouth of its own, which at any future time is ready to repeat that lesson.

The memory of this machine consists of tinfoil thin enough to be impressionable by the metal style which is set in motion by the voice, and yet thick enough to be retentive of these impressions, and at a proper time to communicate a corresponding motion to the style of the talking part of the machine.

Such is the heart of this instrument, by which it gets its speeches. Are our own hearts essentially different? We know what damage can be done to our memory by physical disturbances. We find ourselves quite unable to recall what we had often perused and reperused on the pages of memory. The page is lost out of our consciousness. Time goes on, and some day we find that the page with all that it contained has been restored to its place. Where was that page when it was out of our consciousness? Not surely in the Ego, unless there be an unconscious Ego. It must be out of the Ego, and therefore an Object. If this be so, it is of no great consequence to the dignity of the Ego, whether this particular object is purely spiritual or has a material substratum, just as history is history, whether or not it has a material substratum of paper and ink.

Memory is sometimes spoken of as if it were essential to individuality. When I wish to convince myself that I am the same person as a certain baby, I may do so by remembering as my own certain acts done by that baby. It may happen, however, that I cannot ascertain whether my present memory of these acts is due entirely to the direct impression made by these acts on me, or whether it is not mainly due to the frequent repetition of the story of these acts, as told to me afterwards by older persons.

But even if I were to find my memory to be all wrong, and that I am not that baby but a changeling, this would not touch my conviction that I who now am, am one.

The phenomenon of double consciousness, though not common, seems to be well established. A person has a double series of alternate states. In one the memory, education, accomplishments, and temper, are quite different from what they are in the other.

Instances have even been adduced of a man believing himself to be two or even three different individuals at the same time. But when we come to examine any particular case, we find that the man has nothing more than an erroneous opinion that he is entitled to the position and rights of the King, or of some other person, as well as his own, so that even in his own imagination he is no more than a person who holds several different offices at the same time.

(2.) [Plastidule souls] The theory of Plastidule souls has been hinted at by several persons of whom Dr. Tyndall has spoken loudest. A much clearer utterance is that of Professor von Nageli, of Munich, in an address delivered at the Munich meeting of the German Association in 1877.

Du Bois Reymond, in an address to the same body at Leipzig in 1872, had asserted

`That in the first trace of pleasure which was felt by one of the simplest beings in the beginning of animal life upon our earth, an insuperable limit was marked; while upwards from this to the most elevated mental activity, and downwards from the vital force of the organic to the simple physical force, he nowhere finds another limit.'

To this Professor Nageli replies

`Experience shows that from the clearest consciousness of the thinker downwards, through the more imperfect consciousness of the child, to the unconsciousness of the embryo, and to the insensibility of the human ovum, — or through the more imperfect consciousness of undeveloped human races and of higher animals to the unconsciousness of lower animals and of sensitive plants, and to the insensibility of all other plants, — there exists a continuous gradation without definable limit, and that the same gradation continues from the life of the animal ovum and the vegetable cell downwards, through organised elementary and more or less lifeless forms (parts of the cell), to crystals and chemical molecules.'

Professor von Nageli accepts the fact of sensation, appetency, and thought in the higher forms of life; but instead of trying to resolve it into a mechanical process, he levels up the discontinuity of the chain of being by attributing sensation not only to, all organisms, but also to all cells, molecules, and atoms. This is what he says —

`Now, if the molecules possess anything which is ever so distantly related to sensation, and we cannot doubt it, since each one feels the presence, the certain condition, the peculiar forces of the other, and, accordingly, has the inclination to move, and under circumstances really begins to move — becomes alive as it were; moreover, since such molecules are the elements which cause pleasure and pain; if, therefore, the molecules feel something that is related to sensation, then this must be pleasure, if they can respond to attraction and repulsion, i.e. follow their inclination or disinclination; it must be displeasure if they are forced to execute some opposite movement, and it must be neither pleasure nor displeasure if they remain at rest.'

Professor von Nageli is what Professor Huxley would call a mere biologist, or he would have known that the molecules, like the planets, move along like blessed gods. They cannot be disturbed from the path of their choice by the action of any forces, for they have a constant and perpetual will to render to every force precisely the amount of deflexion which is due to it. They must therefore enjoy a perpetuity of the highest and most unmixed pleasure, even when, as Professor Nageli says, they are the cause of pain to us.

To attribute life, sensation, and thought to objects in which these attributes are not established by sufficient evidence is nothing more than the good old figure of Personification.

If certain bodies, like the sun and stars, move in a regular manner which we can predict, we may, if it pleases us, suppose that their nature is like that of the just man whom nothing can turn from the path of rectitude. If the motion of other bodies is less simple, so that we cannot account for it, we may suppose their nature to be tainted with that capriciousness which we observe in our fellow-men, and of which we are occasionally conscious in ourselves.

But the study of nature has always tended to show that what we formerly attributed to the caprice of bodies is only an instance of a regularity which is unbroken, but which cannot be traced by us till we acquire the requisite skill.

But granting that the mental powers of atoms may be, for anything we know, of the very highest order, what step have we made towards linking our own mental powers with those of lower orders of being?

(3.) [Psychophysik] Let us suppose that a thinking man is built up of a number of thinking atoms. Have the thoughts of the man any relation to the thoughts of atoms or of one or more of them? Those who try to account by means of atoms for mental processes do so not by the thoughts of the atoms, but by their motions.

Hobbes, in the frontispiece of his Leviathan, shows us a monster like the wicker images of our British antecessors stuffed with men, and the whole method of his book is founded on an analogy between the body politic and the individual man.

Herbert Spencer has pushed the analogy both upwards and downwards as far as it will go, and further than it can go on all fours. He shows us how a society is an organism, and how an organism is a society, — how the lower forms of societies and organisms consist of a multitude of homogeneous parts, the functions of which are imperfectly differentiated, so that each can at a pinch undertake the office of any other; whereas the parts of higher forms of organisms and societies are exceedingly heterogeneous, and discharge more perfectly differentiated functions. Hence to the lower forms a breaking up may be a multiplication of the species, whereas to the higher forms it is death.

In a society, as in an organism, both the working and the thinking will be better done if undertaken by different members, provided that the thinking members can guide the working members, while the working members support the thinking members, — the workers retaining just enough intelligence to enable them to receive the guidance, and the thinkers retaining just enough working power to enable them to appropriate the pabulum presented to them by the workers.

Hence in the more highly developed systems the guiding powers may be concentrated into a smaller portion of the whole system, and may exercise a more undisputed power of guiding the rest, till in the highest organism we arrive at what is called Personal Government, and the organism may bear without abuse the grand old name of Individual. This result is brought about by all the members except one bartering their right of guiding themselves for the privilege of being guided, and so delegating to the one ruling member the functions of government. When the human society has lapsed into the condition of personal government, the consciousness of the head of the state may be expressed by him in the phrase, `L'etat c'est moi'; but though the other members of the society may delegate to the head all their political powers, they cannot delegate their sensations or any other fact of consciousness, for these are the incommunicable attributes of that Ego to whom they belong.

I have now to confess that up to the present moment I have remained in ignorance of how I came to be, or, in the Spencerian language, how consciousness must arise. I was dimly aware that somewhere in the vast System of Philosophy this question had been settled, because the Evolutionists are all so calm about it; but in a hasty search for it I never suspected in how quiet and unostentatious a manner the origin of myself would be accounted for. I am indebted to Mr. Kirkman for pointing it out in his Philosophy without Assumptions. Here it is with Mr. Kirkman's comment. Principles of Psychology, § 179, p. 403:

'These separate impressions are received by the senses — by different parts of the body. If they go no further than the places at which they are received, they are useless. Or if only some of them are brought into relation with one another, they are useless. That an effectual adjustment may be made, they must all be brought into relation with one another. But this implies some centre of communication common to them all, through which they severally pass; and, as they cannot pass through it simultaneously, they must pass through it in succession. So that as the external phenomena responded to become greater in number and more complicated in kind, the variety and rapidity of the changes to which this common centre of communication is subject must increase — there must result an unbroken series of these changes — there must arise a consciousness.'(")

On this Kirkman remarks: 'He knew he could do it, and he did it! — What was the evolution of light to this? The next Longinus will put that in before γενέσθω φῶς και ἐγενετο φῶς.'

The opinions about my origin are as various as those about my nature. Canon Liddon tells me that I was created out of nothing in the year 1831, though I cannot make out from what he says on what day of that year the event took place, or why my parents and not some one else found me under a gooseberry bush; or, indeed, why I should have any part or lot in family matters, from Adam's first sin down to my father's last name.

Mr. Francis Galton tells me that I am developed from structureless germs contributed not only by my two parents but by their remotest ancestors centuries ago. My existence, therefore, does not begin abruptly, but tails off as an exponential function of t does for negative values of that variable. My local existence, however, though at present confined within the periphractic region of my skin, was in former times discontinuous as regards space, being carried about by two, four, or more, distinct human beings.

Dr. Julius Muller tells me that by an analysis of my conscience I shall come to a very different result, namely, that I existed (if, indeed, the fact can be expressed by a past tense and not a pure aorist), in an extra-temporal state, and that in that state I freely determined myself to choose evil rather than good. He does not say I can remember this transaction. The conviction I am to acquire of it is not to be an experimental or empirical consciousness, but a speculative or philosophical knowledge.

Since, according to Muller's theory, this extra-temporal decision is perfectly free, and since it would be difficult to predicate freedom of a choice which is invariably on one side, he is obliged to assert that in the extra-temporal state some of our species must have chosen the better part. But he has also to maintain that all of us who are born into this world by ordinary generation have already chosen the worse part. Hence, though he does not say so, he makes the extra-temporal fall a condition of our being born into this world. Whether those of us who make the better choice are born into some other world, or whether, so long as they remain unfallen, they continue in the extra-temporal state — a state certainly not higher but rather more undeveloped than that of time — Muller does not say.

Dr. John Henry Newman has shown us how the doctrine of post-baptismal sin became developed into the discovery of Purgatory with all its geographical details. It would seem as if the doctrine of original sin, in the hands of speculative theologians, might open up to our view a far more transcendental region, compared with which the stairs and terraces and fires of purgatory are as familiar as those of our own hearths and homes.

As to my present state, Du Bois Reymond tells me that not only my bodily but a large part of my mental functions are performed by the motion of atoms under fixed laws, and his result is that the finite mind, as it has developed itself through the animal world up to man, is a double one, — on the one side the acting, inventing, unconscious, material mind, which puts the muscles into motion and determines the world's history: this is nothing else but the mechanics of atoms, and is subject to the causal law; and on the other side the inactive, contemplative, remembering, fancying, conscious, immaterial mind, which feels pleasure and pain, love and hate: this one lies outside of the mechanics of matter and cares nothing for cause and effect.

Dr. Drysdale tells me that not only my thinking powers but my feelings are functions of the material organism, and that I myself am such a function. He admits that I am not material — no function can be material, for matter is a substance, and a function is not a being at all. Dr. Drysdale, as a Christian materialist, follows his master Fletcher, who says

`As often as it shall be said that mind or the faculty of thinking is a property of living matter, — that it is born with the body, is developed with the body, decays with the body, and dies with the body, — it is to be understood of the mind only, not the soul. The soul is something not material indeed, but substantial — a divine gift to the highest alone of God's creatures, responsible for all the actions of mind, but as totally distinct from it as one thing can be from another, or rather as something is from nothing.'(")

Dr. Drysdale, however, in order to save the dynamical theory of life and mind, says that this soul or spirit must either, if now existing, be a passive spectator of the action of the living being connected with it, or else that he has no existence during this present life, but is to be constituted by a divine act after the death of the living being.

In either case, I cannot identify this soul with myself, for I know that I exist now, and that I act, and that what I do may be right or wrong, and that whether right or wrong, it is my act, which I cannot repudiate.

In this search for information about myself from eminent thinkers of different types, I seem to have learnt one lesson, that all science and philosophy and every form of human speech is about objects capable of being perceived by the speaker and the hearer; and that when our thought pretends to deal with the Subject it is really only dealing with an Object under a false name. The only proposition about the Subject, namely, 'I am', cannot be used in the same sense by any two of us, and, therefore, it can never become science at all.

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