Mechanism (philosophy)
Encyclopedia
Mechanism is the belief that natural wholes (principally living things) are like machines or artifacts, composed of parts lacking any intrinsic relationship to each other, and with their order imposed from without. Thus, the source of an apparent thing's activities is not the whole itself, but its parts or an external influence on the parts. Mechanism is opposed to the organic conception of nature best articulated by Aristotle
and more recently elaborated as vitalism
.
The doctrine of mechanism in philosophy
comes in two different flavors. They are both doctrines of metaphysics
, but they are different in scope and ambitions: the first is a global doctrine about nature; the second is a local doctrine about humans and their minds, which is hotly contested. For clarity we might distinguish these two doctrines as universal mechanism and anthropic mechanism.
. Universal mechanism held that the universe is best understood as a completely mechanical system—that is, a system composed entirely of matter
in motion
under a complete and regular system of laws of nature. The mechanists understood the achievements of the scientific revolution
to show that every phenomenon in the universe could eventually be explained in terms of 'mechanical' laws: that is, in terms of natural laws governing the motion and collision of matter. It follows that mechanism is a form of thoroughgoing determinism
: if all phenomena can be explained entirely through the motion of matter under physical laws, then just as surely as the gears of a clock completely determine that it will strike 2:00 an hour after it strikes 1:00, all phenomena are completely determined by the properties of that matter and the operations of those natural laws.
Indeed, the determinism implied by universal mechanism is even stronger than clockwork.
Whereas the mechanism of a clock may cease to work predictably as its parts break down, the "parts" of the system in universal mechanism are nothing less than everything in the universe — anything that they "broke down" into would still be a part of the universe, and so would still be subject to the mechanistic laws of nature.
The French mechanist and determinist Pierre Simon de Laplace formulated the sweeping implications of this thesis by saying:
One of the first and most famous expositions of universal mechanism is found in the opening passages of the Leviathan
by Thomas Hobbes
(1651). What is less frequently appreciated is that René Descartes
, who is today remembered mainly as a paradigmatic enemy of materialism and mechanism (and in that respect quite the opposite of Hobbes), also did much to advance the mechanistic understanding of nature, in both his scientific works on mechanics and in his philosophical works on metaphysics
.
Descartes was a substance dualist, and argued that reality was composed of two radically different types of substance: corporeal substance, on the one hand, and mental substance
, on the other hand. Descartes steadfastly denied that the human mind could be explained in terms of the configurations of corporeal substance (a chief claim of all forms of mechanism). Nevertheless, his understanding of corporeal substance was thoroughly mechanistic.
His scientific work was based on the understanding of all natural objects, including not only billiard balls and rocks, but also non-human animals and even human bodies, as completely mechanistic automata
. Descartes' dualism was, in no small part, motivated by the fact that he could see no place for the soul or for freedom of the will in his thoroughly mechanistic understanding of nature. Ancient naturalists such as Aristotle
, on the other hand, had no need for substance dualism because their conception of nature was teleological rather than mechanistic, and was compatible with a robust sense of human freedom. Descartes, then, can be seen as agreeing with the early modern mechanists, and disagreeing with Aristotle, on the nature of the physical world. The difference between Descartes and his mechanist colleagues was that mechanists either saw no problem for the notions of soul and freedom of the will, or else were simply willing to dispense with these notions altogether.
The mechanistic worldview gained considerable favor with the revolutionary successes of Isaac Newton
, whose work in mechanics seemed to successfully explain the motion of everything in heaven and in earth according to the operation of a single mechanical principle. To be sure, that principle — universal gravitation — was something of a disappointment to the older cadre of mechanists, since mechanism originally sought to explain all phenomena entirely in terms of the motion and collision of material bodies, whereas Newton's principle of gravitation required action at a distance
. Nevertheless, the generation of philosophers who were inspired by Newton's example carried the mechanist banner. Chief among them were French philosophers
such as Julien Offray de La Mettrie
and Denis Diderot
(see also: French materialism
).
One of the chief obstacles that all mechanistic theories have faced is providing a mechanistic explanation of the human mind; Descartes, for one, endorsed dualism
in spite of endorsing a completely mechanistic conception of the material world because he argued that mechanism and the notion of a mind were logically incompatible. Hobbes, on the other hand, conceived of the mind and the will as purely mechanistic, completely explicable in terms of the effects of perception and the pursuit of desire, which in turn he held to be completely explicable in terms of the materialistic operations of the nervous system. Following Hobbes, other mechanists argued for a thoroughly mechanistic explanation of the mind, with one of the most influential and controversial expositions of the doctrine being offered by Julien Offray de La Mettrie
in his Man a Machine (1748).
Today, as in the past, the main points of debate between anthropic mechanists and anti-mechanists are mainly occupied with two topics: the mind — and consciousness, in particular — and free will
. Anti-mechanists argue that anthropic mechanism is incompatible with our commonsense intuitions: in philosophy of mind
they argue that unconscious matter cannot completely explain the phenomenon of consciousness, and in metaphysics
they argue that anthropic mechanism implies determinism about human action, which (they argue) is incompatible with our understanding of ourselves as creatures with free will
. Contemporary philosophers who have argued for this position include Norman Malcolm
and
David Chalmers
.
Anthropic mechanists typically respond in one of two ways. In the first, they agree with anti-mechanists that mechanism conflicts with some of our commonsense intuitions, but go on to argue that our commonsense intuitions are simply mistaken and need to be revised. Down this path lies eliminative materialism
in philosophy of mind
, and hard determinism
on the question of free will. This option is popular with some scientists, but it is rejected by most philosophers, although not by its most well-known advocate, the eliminative materialist philosopher Paul Churchland
. What is far from clear is how eliminative materialism is compatibile with the freedom of will apparently required for anyone (including its adherents) to make truth claims. The second option, common amongst philosophers who adopt anthropic mechanism, is to argue that the argument
s given for incompatibility are specious: whatever it is we mean by "consciousness" and "free will," they urge, it is fully compatible with a mechanistic understanding of the human mind and will. As a result they tend to argue for one or another non-eliminativist physicalist
theories of mind, and for compatibilism
on the question of free will. Contemporary philosophers who have argued for this sort of account include J. J. C. Smart
and Daniel Dennett
.
imply about anthropic mechanism. Much of the debate centers on whether the human mind is equivalent to a Turing machine
, or by the Church-Turing thesis, any finite machine at all. If it is, and if the machine is consistent
, then Gödel's incompleteness theorems would apply to it.
One of the earliest attempts to use incompleteness to reason about human intelligence was by Gödel himself in his 1951 Gibbs lecture entitled "Some basic theorems on the foundations of mathematics and their philosophical implications". In this lecture, Gödel uses the incompleteness theorem to arrive at the following disjunction: (a) the human mind is not a consistent finite machine, or (b) there exist Diophantine equations for which it cannot decide whether solutions exist. Gödel finds (b) implausible, and thus seems to have believed the human mind was not equivalent to a finite machine, i.e., its power exceeded that of any finite machine. He recognized that this was only a conjecture, since one could never disprove (b). Yet he considered the disjunctive conclusion to be a "certain fact".
In subsequent years, more direct anti-mechanist lines of reasoning were apparently floating around the intellectual atmosphere. In 1960, Hilary Putnam
published a paper entitled "Minds and Machines," in which he points out the flaws of a typical anti-mechanist argument. Informally, this is the argument that the (alleged) difference between "what can be mechanically proven" and "what can be seen to be true by humans" shows that human intelligence is not mechanical in nature. Or, as Putnam puts it:
Hilary Putnam
objects that this argument ignores the issue of consistency. Gödel's technique can only be applied to consistent systems. It is conceivable, argues Putnam, that the human mind is inconsistent. If one is to use Gödel's technique to prove the proposition that T cannot prove, one must first prove (the mathematical statement representing) the consistency of T, a daunting and perhaps impossible task. Later Putnam suggested that while Gödel's theorems cannot be applied to humans, since they make mistakes and are therefore inconsistent, it may be applied to the human faculty of science or mathematics in general. If we are to believe that it is consistent, then either we cannot prove its consistency, or it cannot be represented by a Turing machine.
J. R. Lucas in Minds, Machines and Gödel
(1963), and later in his book The Freedom of the Will (1970), lays out an anti-mechanist argument closely following the one described by Putnam, including reasons for why the human mind can be considered consistent. Lucas admits that, by Gödel's second theorem, a human mind cannot formally prove its own consistency, and even says (perhaps facetiously) that women and politicians are inconsistent. Nevertheless, he sets out arguments for why a male non-politician can be considered consistent. These arguments are philosophical in nature and are the subject of much debate; Lucas provides references to responses on his own website.
Another work was done by Judson Webb in his 1968 paper "Metamathematics and the Philosophy of Mind". Webb claims that previous attempts have glossed over whether one truly can see that the Gödelian statement p pertaining to oneself, is true. Using a different formulation of Gödel's theorems, namely, that of Raymond Smullyan
and Emil Post, Webb shows one can derive convincing arguments for oneself of both the truth and falsity of p. He furthermore argues that all arguments about the philosophical implications of Gödel's theorems are really arguments about whether the Church-Turing thesis is true.
Later, Roger Penrose
entered the fray, providing somewhat novel anti-mechanist arguments in his books, The Emperor's New Mind
(1989) [ENM] and Shadows of the Mind
(1994) [SM]. These books have proved highly controversial. Martin Davis
responded to ENM in his paper "Is Mathematical Insight Algorithmic?" (ps), where he argues that Penrose ignores the issue of consistency. Solomon Feferman
gives a critical examination of SM in his paper "Penrose's Gödelian argument" (pdf).
One of the most lucid statements of a Gödel based anti-mechanism argument can be found in Douglas Hofstadter
's Pulitzer Prize winning book Gödel, Escher, Bach: An Eternal Golden Braid. This is particularly interesting, in that Hofstadter is widely viewed as one of the better known skeptics of such argument:
Aristotle
Aristotle was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology...
and more recently elaborated as vitalism
Vitalism
Vitalism, as defined by the Merriam-Webster dictionary, is#a doctrine that the functions of a living organism are due to a vital principle distinct from biochemical reactions...
.
The doctrine of mechanism in philosophy
Philosophy
Philosophy is the study of general and fundamental problems, such as those connected with existence, knowledge, values, reason, mind, and language. Philosophy is distinguished from other ways of addressing such problems by its critical, generally systematic approach and its reliance on rational...
comes in two different flavors. They are both doctrines of metaphysics
Metaphysics
Metaphysics is a branch of philosophy concerned with explaining the fundamental nature of being and the world, although the term is not easily defined. Traditionally, metaphysics attempts to answer two basic questions in the broadest possible terms:...
, but they are different in scope and ambitions: the first is a global doctrine about nature; the second is a local doctrine about humans and their minds, which is hotly contested. For clarity we might distinguish these two doctrines as universal mechanism and anthropic mechanism.
Universal mechanism
The older doctrine which we have called universal mechanism is a theory about the nature of the universe, closely linked with the early modern version of materialismMaterialism
In philosophy, the theory of materialism holds that the only thing that exists is matter; that all things are composed of material and all phenomena are the result of material interactions. In other words, matter is the only substance...
. Universal mechanism held that the universe is best understood as a completely mechanical system—that is, a system composed entirely of matter
Matter
Matter is a general term for the substance of which all physical objects consist. Typically, matter includes atoms and other particles which have mass. A common way of defining matter is as anything that has mass and occupies volume...
in motion
Motion (physics)
In physics, motion is a change in position of an object with respect to time. Change in action is the result of an unbalanced force. Motion is typically described in terms of velocity, acceleration, displacement and time . An object's velocity cannot change unless it is acted upon by a force, as...
under a complete and regular system of laws of nature. The mechanists understood the achievements of the scientific revolution
Scientific revolution
The Scientific Revolution is an era associated primarily with the 16th and 17th centuries during which new ideas and knowledge in physics, astronomy, biology, medicine and chemistry transformed medieval and ancient views of nature and laid the foundations for modern science...
to show that every phenomenon in the universe could eventually be explained in terms of 'mechanical' laws: that is, in terms of natural laws governing the motion and collision of matter. It follows that mechanism is a form of thoroughgoing determinism
Determinism
Determinism is the general philosophical thesis that states that for everything that happens there are conditions such that, given them, nothing else could happen. There are many versions of this thesis. Each of them rests upon various alleged connections, and interdependencies of things and...
: if all phenomena can be explained entirely through the motion of matter under physical laws, then just as surely as the gears of a clock completely determine that it will strike 2:00 an hour after it strikes 1:00, all phenomena are completely determined by the properties of that matter and the operations of those natural laws.
Indeed, the determinism implied by universal mechanism is even stronger than clockwork.
Whereas the mechanism of a clock may cease to work predictably as its parts break down, the "parts" of the system in universal mechanism are nothing less than everything in the universe — anything that they "broke down" into would still be a part of the universe, and so would still be subject to the mechanistic laws of nature.
The French mechanist and determinist Pierre Simon de Laplace formulated the sweeping implications of this thesis by saying:
- "We may regard the present state of the universe as the effect of the past and the cause of the future. An intellect which at any given moment knew all of the forces that animate nature and the mutual positions of the beings that compose it, if this intellect were vast enough to submit the data to analysis, could condense into a single formula the movement of the greatest bodies of the universe and that of the lightest atomAtomThe atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...
; for such an intellect nothing could be uncertain and the future just like the past would be present before its eyes." Pierre Simon Laplace, A Philosophical Essay on Probabilities
One of the first and most famous expositions of universal mechanism is found in the opening passages of the Leviathan
Leviathan (book)
Leviathan or The Matter, Forme and Power of a Common Wealth Ecclesiasticall and Civil — commonly called simply Leviathan — is a book written by Thomas Hobbes and published in 1651. Its name derives from the biblical Leviathan...
by Thomas Hobbes
Thomas Hobbes
Thomas Hobbes of Malmesbury , in some older texts Thomas Hobbs of Malmsbury, was an English philosopher, best known today for his work on political philosophy...
(1651). What is less frequently appreciated is that René Descartes
René Descartes
René Descartes ; was a French philosopher and writer who spent most of his adult life in the Dutch Republic. He has been dubbed the 'Father of Modern Philosophy', and much subsequent Western philosophy is a response to his writings, which are studied closely to this day...
, who is today remembered mainly as a paradigmatic enemy of materialism and mechanism (and in that respect quite the opposite of Hobbes), also did much to advance the mechanistic understanding of nature, in both his scientific works on mechanics and in his philosophical works on metaphysics
Metaphysics
Metaphysics is a branch of philosophy concerned with explaining the fundamental nature of being and the world, although the term is not easily defined. Traditionally, metaphysics attempts to answer two basic questions in the broadest possible terms:...
.
Descartes was a substance dualist, and argued that reality was composed of two radically different types of substance: corporeal substance, on the one hand, and mental substance
Mental substance
Mental substance refers to the concept held by dualists and idealists, that minds are made-up of non-physical substance. This substance is often referred to as consciousness....
, on the other hand. Descartes steadfastly denied that the human mind could be explained in terms of the configurations of corporeal substance (a chief claim of all forms of mechanism). Nevertheless, his understanding of corporeal substance was thoroughly mechanistic.
- "I should like you to consider that these functions (including passion, memory, and imagination) follow from the mere arrangement of the machine’s organs every bit as naturally as the movements of a clock or other automaton follow from the arrangement of its counter-weights and wheels." (Descartes, Treatise on Man, p.108)
His scientific work was based on the understanding of all natural objects, including not only billiard balls and rocks, but also non-human animals and even human bodies, as completely mechanistic automata
Automaton
An automaton is a self-operating machine. The word is sometimes used to describe a robot, more specifically an autonomous robot. An alternative spelling, now obsolete, is automation.-Etymology:...
. Descartes' dualism was, in no small part, motivated by the fact that he could see no place for the soul or for freedom of the will in his thoroughly mechanistic understanding of nature. Ancient naturalists such as Aristotle
Aristotle
Aristotle was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology...
, on the other hand, had no need for substance dualism because their conception of nature was teleological rather than mechanistic, and was compatible with a robust sense of human freedom. Descartes, then, can be seen as agreeing with the early modern mechanists, and disagreeing with Aristotle, on the nature of the physical world. The difference between Descartes and his mechanist colleagues was that mechanists either saw no problem for the notions of soul and freedom of the will, or else were simply willing to dispense with these notions altogether.
The mechanistic worldview gained considerable favor with the revolutionary successes of Isaac Newton
Isaac Newton
Sir Isaac Newton PRS was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, who has been "considered by many to be the greatest and most influential scientist who ever lived."...
, whose work in mechanics seemed to successfully explain the motion of everything in heaven and in earth according to the operation of a single mechanical principle. To be sure, that principle — universal gravitation — was something of a disappointment to the older cadre of mechanists, since mechanism originally sought to explain all phenomena entirely in terms of the motion and collision of material bodies, whereas Newton's principle of gravitation required action at a distance
Action at a distance (physics)
In physics, action at a distance is the interaction of two objects which are separated in space with no known mediator of the interaction. This term was used most often in the context of early theories of gravity and electromagnetism to describe how an object responds to the influence of distant...
. Nevertheless, the generation of philosophers who were inspired by Newton's example carried the mechanist banner. Chief among them were French philosophers
Philosophy
Philosophy is the study of general and fundamental problems, such as those connected with existence, knowledge, values, reason, mind, and language. Philosophy is distinguished from other ways of addressing such problems by its critical, generally systematic approach and its reliance on rational...
such as Julien Offray de La Mettrie
Julien Offray de La Mettrie
Julien Offray de La Mettrie was a French physician and philosopher, and one of the earliest of the French materialists of the Enlightenment...
and Denis Diderot
Denis Diderot
Denis Diderot was a French philosopher, art critic, and writer. He was a prominent person during the Enlightenment and is best known for serving as co-founder and chief editor of and contributor to the Encyclopédie....
(see also: French materialism
French materialism
French materialism is the name given to a handful of French 18th century philosophers during the Age of Enlightenment, many of them clustered around the salon of Baron d'Holbach...
).
Anthropic mechanism
The debate over anthropic mechanism seems here to stay, at least for the time being. The thesis in anthropic mechanism is not that everything can be completely explained in mechanical terms (although some anthropic mechanists may also believe that), but rather that everything about human beings can be completely explained in mechanical terms, as surely as can everything about clockwork or gasoline engines.One of the chief obstacles that all mechanistic theories have faced is providing a mechanistic explanation of the human mind; Descartes, for one, endorsed dualism
Dualism (philosophy of mind)
In philosophy of mind, dualism is a set of views about the relationship between mind and matter, which begins with the claim that mental phenomena are, in some respects, non-physical....
in spite of endorsing a completely mechanistic conception of the material world because he argued that mechanism and the notion of a mind were logically incompatible. Hobbes, on the other hand, conceived of the mind and the will as purely mechanistic, completely explicable in terms of the effects of perception and the pursuit of desire, which in turn he held to be completely explicable in terms of the materialistic operations of the nervous system. Following Hobbes, other mechanists argued for a thoroughly mechanistic explanation of the mind, with one of the most influential and controversial expositions of the doctrine being offered by Julien Offray de La Mettrie
Julien Offray de La Mettrie
Julien Offray de La Mettrie was a French physician and philosopher, and one of the earliest of the French materialists of the Enlightenment...
in his Man a Machine (1748).
Today, as in the past, the main points of debate between anthropic mechanists and anti-mechanists are mainly occupied with two topics: the mind — and consciousness, in particular — and free will
Free will
"To make my own decisions whether I am successful or not due to uncontrollable forces" -Troy MorrisonA pragmatic definition of free willFree will is the ability of agents to make choices free from certain kinds of constraints. The existence of free will and its exact nature and definition have long...
. Anti-mechanists argue that anthropic mechanism is incompatible with our commonsense intuitions: in philosophy of mind
Philosophy of mind
Philosophy of mind is a branch of philosophy that studies the nature of the mind, mental events, mental functions, mental properties, consciousness and their relationship to the physical body, particularly the brain. The mind-body problem, i.e...
they argue that unconscious matter cannot completely explain the phenomenon of consciousness, and in metaphysics
Metaphysics
Metaphysics is a branch of philosophy concerned with explaining the fundamental nature of being and the world, although the term is not easily defined. Traditionally, metaphysics attempts to answer two basic questions in the broadest possible terms:...
they argue that anthropic mechanism implies determinism about human action, which (they argue) is incompatible with our understanding of ourselves as creatures with free will
Free will
"To make my own decisions whether I am successful or not due to uncontrollable forces" -Troy MorrisonA pragmatic definition of free willFree will is the ability of agents to make choices free from certain kinds of constraints. The existence of free will and its exact nature and definition have long...
. Contemporary philosophers who have argued for this position include Norman Malcolm
Norman Malcolm
Norman Malcolm was an American philosopher, born in Selden, Kansas. He studied philosophy with O.K. Bouwsma at the University of Nebraska, then enrolled as a graduate student at Harvard University in 1933....
and
David Chalmers
David Chalmers
David John Chalmers is an Australian philosopher specializing in the area of philosophy of mind and philosophy of language, whose recent work concerns verbal disputes. He is Professor of Philosophy and Director of the Centre for Consciousness at the Australian National University...
.
Anthropic mechanists typically respond in one of two ways. In the first, they agree with anti-mechanists that mechanism conflicts with some of our commonsense intuitions, but go on to argue that our commonsense intuitions are simply mistaken and need to be revised. Down this path lies eliminative materialism
Eliminative materialism
Eliminative materialism is a materialist position in the philosophy of mind. Its primary claim is that people's common-sense understanding of the mind is false and that certain classes of mental states that most people believe in do not exist...
in philosophy of mind
Philosophy of mind
Philosophy of mind is a branch of philosophy that studies the nature of the mind, mental events, mental functions, mental properties, consciousness and their relationship to the physical body, particularly the brain. The mind-body problem, i.e...
, and hard determinism
Hard determinism
Hard determinism, or Metaphysical determinism, defends the strongest version of Determinism: the world is a mechanism, and all events and choices have been determined by earlier conditions. Particularly, they accept Causal Determinism and Logical Determinism. Faced with the Standard argument...
on the question of free will. This option is popular with some scientists, but it is rejected by most philosophers, although not by its most well-known advocate, the eliminative materialist philosopher Paul Churchland
Paul Churchland
Paul Churchland is a philosopher noted for his studies in neurophilosophy and the philosophy of mind. He is currently a Professor at the University of California, San Diego, where he holds the Valtz Chair of Philosophy. Churchland holds a joint appointment with the Cognitive Science Faculty and...
. What is far from clear is how eliminative materialism is compatibile with the freedom of will apparently required for anyone (including its adherents) to make truth claims. The second option, common amongst philosophers who adopt anthropic mechanism, is to argue that the argument
Argument
In philosophy and logic, an argument is an attempt to persuade someone of something, or give evidence or reasons for accepting a particular conclusion.Argument may also refer to:-Mathematics and computer science:...
s given for incompatibility are specious: whatever it is we mean by "consciousness" and "free will," they urge, it is fully compatible with a mechanistic understanding of the human mind and will. As a result they tend to argue for one or another non-eliminativist physicalist
Physicalism
Physicalism is a philosophical position holding that everything which exists is no more extensive than its physical properties; that is, that there are no kinds of things other than physical things...
theories of mind, and for compatibilism
Compatibilism
Compatibilism is the belief that free will and determinism are compatible ideas, and that it is possible to believe both without being logically inconsistent. It may, however, be more accurate to say that compatibilists define 'free will' in a way that allows it to co-exist with determinism...
on the question of free will. Contemporary philosophers who have argued for this sort of account include J. J. C. Smart
J. J. C. Smart
John Jamieson Carswell "Jack" Smart AC is an Australian philosopher and academic who is currently Emeritus Professor of Philosophy at Monash University, Australia...
and Daniel Dennett
Daniel Dennett
Daniel Clement Dennett is an American philosopher, writer and cognitive scientist whose research centers on the philosophy of mind, philosophy of science and philosophy of biology, particularly as those fields relate to evolutionary biology and cognitive science. He is currently the Co-director of...
.
Gödelian arguments
Some scholars have debated over what, if anything, Gödel's incompleteness theoremsGödel's incompleteness theorems
Gödel's incompleteness theorems are two theorems of mathematical logic that establish inherent limitations of all but the most trivial axiomatic systems capable of doing arithmetic. The theorems, proven by Kurt Gödel in 1931, are important both in mathematical logic and in the philosophy of...
imply about anthropic mechanism. Much of the debate centers on whether the human mind is equivalent to a Turing machine
Turing machine
A Turing machine is a theoretical device that manipulates symbols on a strip of tape according to a table of rules. Despite its simplicity, a Turing machine can be adapted to simulate the logic of any computer algorithm, and is particularly useful in explaining the functions of a CPU inside a...
, or by the Church-Turing thesis, any finite machine at all. If it is, and if the machine is consistent
Consistency
Consistency can refer to:* Consistency , the psychological need to be consistent with prior acts and statements* "Consistency", an 1887 speech by Mark Twain...
, then Gödel's incompleteness theorems would apply to it.
One of the earliest attempts to use incompleteness to reason about human intelligence was by Gödel himself in his 1951 Gibbs lecture entitled "Some basic theorems on the foundations of mathematics and their philosophical implications". In this lecture, Gödel uses the incompleteness theorem to arrive at the following disjunction: (a) the human mind is not a consistent finite machine, or (b) there exist Diophantine equations for which it cannot decide whether solutions exist. Gödel finds (b) implausible, and thus seems to have believed the human mind was not equivalent to a finite machine, i.e., its power exceeded that of any finite machine. He recognized that this was only a conjecture, since one could never disprove (b). Yet he considered the disjunctive conclusion to be a "certain fact".
In subsequent years, more direct anti-mechanist lines of reasoning were apparently floating around the intellectual atmosphere. In 1960, Hilary Putnam
Hilary Putnam
Hilary Whitehall Putnam is an American philosopher, mathematician and computer scientist, who has been a central figure in analytic philosophy since the 1960s, especially in philosophy of mind, philosophy of language, philosophy of mathematics, and philosophy of science...
published a paper entitled "Minds and Machines," in which he points out the flaws of a typical anti-mechanist argument. Informally, this is the argument that the (alleged) difference between "what can be mechanically proven" and "what can be seen to be true by humans" shows that human intelligence is not mechanical in nature. Or, as Putnam puts it:
Let T be a Turing machine which "represents" me in the sense that T can prove just the mathematical statements I prove. Then using Gödel's technique I can discover a proposition that T cannot prove, and moreover I can prove this proposition. This refutes the assumption that T "represents" me, hence I am not a Turing machine.
Hilary Putnam
Hilary Putnam
Hilary Whitehall Putnam is an American philosopher, mathematician and computer scientist, who has been a central figure in analytic philosophy since the 1960s, especially in philosophy of mind, philosophy of language, philosophy of mathematics, and philosophy of science...
objects that this argument ignores the issue of consistency. Gödel's technique can only be applied to consistent systems. It is conceivable, argues Putnam, that the human mind is inconsistent. If one is to use Gödel's technique to prove the proposition that T cannot prove, one must first prove (the mathematical statement representing) the consistency of T, a daunting and perhaps impossible task. Later Putnam suggested that while Gödel's theorems cannot be applied to humans, since they make mistakes and are therefore inconsistent, it may be applied to the human faculty of science or mathematics in general. If we are to believe that it is consistent, then either we cannot prove its consistency, or it cannot be represented by a Turing machine.
J. R. Lucas in Minds, Machines and Gödel
Minds, Machines and Gödel
Minds, Machines and Gödel is J. R. Lucas's 1959 philosophical paper in which he argues that a human mathematician cannot be accurately represented by an algorithmic automaton...
(1963), and later in his book The Freedom of the Will (1970), lays out an anti-mechanist argument closely following the one described by Putnam, including reasons for why the human mind can be considered consistent. Lucas admits that, by Gödel's second theorem, a human mind cannot formally prove its own consistency, and even says (perhaps facetiously) that women and politicians are inconsistent. Nevertheless, he sets out arguments for why a male non-politician can be considered consistent. These arguments are philosophical in nature and are the subject of much debate; Lucas provides references to responses on his own website.
Another work was done by Judson Webb in his 1968 paper "Metamathematics and the Philosophy of Mind". Webb claims that previous attempts have glossed over whether one truly can see that the Gödelian statement p pertaining to oneself, is true. Using a different formulation of Gödel's theorems, namely, that of Raymond Smullyan
Raymond Smullyan
Raymond Merrill Smullyan is an American mathematician, concert pianist, logician, Taoist philosopher, and magician.Born in Far Rockaway, New York, his first career was stage magic. He then earned a BSc from the University of Chicago in 1955 and his Ph.D. from Princeton University in 1959...
and Emil Post, Webb shows one can derive convincing arguments for oneself of both the truth and falsity of p. He furthermore argues that all arguments about the philosophical implications of Gödel's theorems are really arguments about whether the Church-Turing thesis is true.
Later, Roger Penrose
Roger Penrose
Sir Roger Penrose OM FRS is an English mathematical physicist and Emeritus Rouse Ball Professor of Mathematics at the Mathematical Institute, University of Oxford and Emeritus Fellow of Wadham College...
entered the fray, providing somewhat novel anti-mechanist arguments in his books, The Emperor's New Mind
The Emperor's New Mind
The Emperor's New Mind: Concerning Computers, Minds and The Laws of Physics is a 1989 book by mathematical physicist Sir Roger Penrose.Penrose presents the argument that human consciousness is non-algorithmic, and thus is not capable of being modeled by a conventional Turing machine-type of digital...
(1989) [ENM] and Shadows of the Mind
Shadows of the Mind
Shadows of the Mind: A Search for the Missing Science of Consciousness is a 1994 book by mathematical physicist Roger Penrose, and serves as a followup to his 1989 book The Emperor's New Mind: Concerning Computers, Minds and The Laws of Physics....
(1994) [SM]. These books have proved highly controversial. Martin Davis
Martin Davis
Martin David Davis, is an American mathematician, known for his work on Hilbert's tenth problem . He received his Ph.D. from Princeton University in 1950, where his adviser was Alonzo Church . He is Professor Emeritus at New York University. He is the co-inventor of the Davis-Putnam and the DPLL...
responded to ENM in his paper "Is Mathematical Insight Algorithmic?" (ps), where he argues that Penrose ignores the issue of consistency. Solomon Feferman
Solomon Feferman
Solomon Feferman is an American philosopher and mathematician with major works in mathematical logic.He was born in New York City, New York, and received his Ph.D. in 1957 from the University of California, Berkeley under Alfred Tarski...
gives a critical examination of SM in his paper "Penrose's Gödelian argument" (pdf).
One of the most lucid statements of a Gödel based anti-mechanism argument can be found in Douglas Hofstadter
Douglas Hofstadter
Douglas Richard Hofstadter is an American academic whose research focuses on consciousness, analogy-making, artistic creation, literary translation, and discovery in mathematics and physics...
's Pulitzer Prize winning book Gödel, Escher, Bach: An Eternal Golden Braid. This is particularly interesting, in that Hofstadter is widely viewed as one of the better known skeptics of such argument:
Looked at this way, Gödel's proof suggests – though by no means does it prove! – that there could be some high-level way of viewing the mind/brain, involving concepts which do not appear on lower levels, and that this level might have explanatory power that does not exist – not even in principle – on lower levels. It would mean that some facts could be explained on the high level quite easily, but not on lower levels at all. No matter how long and cumbersome a low-level statement were made, it would not explain the phenomena in question.
It is analogous to the fact that, if you make derivation after derivation in Peano arithmetic, no matter how long and cumbersome you make them, you will never come up with one for G – despite the fact that on a higher level, you can see that the Gödel sentence is true.
What might such high-level concepts be? It has been proposed for eons, by various holistically or "soulistically" inclined scientists and humanists that consciousness is a phenomenon that escapes explanation in terms of brain components; so here is a candidate at least. There is also the ever-puzzling notion of free will. So perhaps these qualities could be "emergent" in the sense of requiring explanations which cannot be furnished by the physiology alone
(Gödel, Escher, Bach, p. 708).
See also
- AutomatonAutomatonAn automaton is a self-operating machine. The word is sometimes used to describe a robot, more specifically an autonomous robot. An alternative spelling, now obsolete, is automation.-Etymology:...
- Descartes
- Digital philosophyDigital philosophyDigital philosophy is a direction in philosophy and cosmology advocated by certain mathematicians and theoretical physicists, e.g., Gregory Chaitin, Edward Fredkin, Stephen Wolfram, and Konrad Zuse ....
- Neural DarwinismNeural DarwinismNeural Darwinism, a large scale theory of brain function by Gerald Edelman, was initially published in 1978, in a book called The Mindful Brain...
in relation to anthropic mechanism - Philosophy of physicsPhilosophy of physicsIn philosophy, the philosophy of physics studies the fundamental philosophical questions underlying modern physics, the study of matter and energy and how they interact. The philosophy of physics begins by reflecting on the basic metaphysical and epistemological questions posed by physics:...
External links
- An overview of attempts to define "life"
- "The Problem of Mechanism" by David L. Schindler (from Beyond Mechanism) - contrasts the Aristotelian and Cartesian views of nature and how the latter engendered the mechanical philosophy