Determinism

This article is about the general notion of determinism in philosophy. For other uses of the word "determinism" see: Deterministic (disambiguation).

Determinism is the philosophical proposition that every event, including human cognition and action, is causally determined by an unbroken chain of prior occurrences. No mysterious miracles or wholly random events occur.

Philosophy of determinism

The principal consequence of deterministic philosophy is that free will (except as defined in strict compatibilism) becomes an illusion. It is a popular misconception that determinism necessarily entails that all future events have already been predetermined and will necessarily happen (a position known as Fatalism); this is not obviously the case, and the subject is still debated among metaphysicians. Determinism is associated with, and relies upon, the ideas of Materialism and Causality. Some of the philosophers who have dealt with this issue are Omar Khayyám, David Hume, Thomas Hobbes, Immanuel Kant, Paul Henri Thiry, Baron d'Holbach and, more recently, John Searle.

With Earth's first Clay They did the Last Man's knead,

And then of the Last Harvest sow'd the Seed:

Yea, the first Morning of Creation wrote

What the Last Dawn of Reckoning shall read.

(Rubaiyat of Omar Khayyam, LIII, rendered into English verse by Edward FitzGerald)

The nature of determinism

The exact meaning of the term "determinism" has historically been subject to various interpretations. Some view determinism and free will as mutually exclusive, whereas others, labelled "Compatibilists", believe that the two ideas can be coherently reconciled. Most of this disagreement is due to the fact that the definition of "free will," like determinism, varies. Some feel it refers to the metaphysical truth of independent agency, whereas others simply define it as the feeling of agency that humans experience when they act. For example, David Hume argued that while it is possible that one does not freely arrive at one's set of desires and beliefs, the only meaningful interpretation of freedom relates to one's ability to translate those desires and beliefs into voluntary action.

Determinism in Western tradition

The idea that the entire universe is a deterministic system has been articulated in both Western and non-Western religion, philosophy, and literature. The Ancient Greek atomists Leucippus and Democritus were the first to anticipate determinism when they theorized that all processes in the world were due to the mechanical interplay of atoms, but this theory did not gain much support at the time. Determinism in the West is often associated with Newtonian physics, which depicts the physical matter of the universe as operating according to a set of fixed, knowable laws. The "billiard ball" hypothesis, a product of Newtonian physics, argues that once the initial conditions of the universe have been established the rest of the history of the universe follows inevitably. If it were actually possible to have complete knowledge of physical matter and all of the laws governing that matter at any one time, then it would be theoretically possible to compute the time and place of every event that will ever occur (Laplace's demon). In this sense, the basic particles of the universe operate in the same fashion as the rolling balls on a billiard table, moving and striking each other in predictable ways to produce predictable results.

Whether or not it is all-encompassing in so doing, Newtonian mechanics deals only with caused events, e.g.: If the original position of an object is x, y, z, and if it is hit dead on by an object moving along some vector V, then it will be pushed straight toward another point x', y', z'. If it goes somewhere else, the Newtonians argue, one must question one's measurements of the original position of the object, the exact direction of the object moving on V, gravitational or other fields that were inadvertently ignored, etc. Then, they maintain, repeated experiments and improvements in accuracy will always bring one's observations closer to the theoretically predicted results. When dealing with situations on an ordinary human scale, Newtonian physics has been so enormously successful that it has no competition. But it fails spectacularly as velocities become some substantial fraction of the speed of light and when interactions at the atomic scale are studied. Prior to the discovery of quantum effects and other challenges to Newtonian physics, "uncertainty" was always a term that applied to the accuracy of human knowledge about causes and effects, and not to the causes and effects themselves.

Determinism in Eastern tradition

In the East, determinism has been expressed in the Buddhist doctrine of Dependent Origination, which states that every phenomenon is conditioned by, and depends on, the phenomena that it is not. A common teaching story, called Indra's Net, illustrates this point using a metaphor. A vast auditorium is decorated with mirrors and/or prisms hanging on strings of different lengths from an immense number of points on the ceiling. One flash of light is sufficient to light the entire display since light bounces and bends from hanging bauble to hanging bauble. Each bauble lights each and every other bauble. So, too, each of us is "lit" by each and every other entity in the Universe. In Buddhism, this teaching is used to demonstrate that to ascribe special value to any one thing is to ignore the interdependence of all things. Volitions of all sentient creatures determine the seeming reality in which we perceive ourself as living, rather than a mechanical universe determining the volitions which humans imagine themselves to be forming.

In the story of the Indra's Net, the light that streams back and forth throughout the display is the analog of karma. The word "karma" does not mean anything like "the result of a past good or bad action." "Karma" refers to an action, or, more specifically, to an intentional action, and the Buddhist theory holds that every karma (every intentional action) will bear karmic fruit (produce an effect somewhere down the line). Karma is the only thing that is fundamentally real. Volitional acts drive the universe. The consequences of this view often confound our ordinary expectations -- much in the way quantum physics has results that are strongly counterintuitive. Fritjiof Capra has written extensively on the parallels and differences among western physics and other systems of thought in his book The Tao of Physics.

A shifting flow of probabilities for futures lies at the heart of theories associated with the Yi Jing (or I Ching, the Book of Changes). Probabilities take the center of the stage away from things and people. A kind of "divine" volition sets the fundamental rules for the working out of probabilities in the universe, and human volitions are always a factor in the ways that humans can deal with the real world situations one encounters. If one's situation in life is surfing on a tsunami, one still has some range of choices even in that situation. One person might give up, and another person might choose to struggle and perhaps to survive. The Yi Jing mentality is much closer to the mentality of quantum physics than to that of classical physics, and also finds parallelism in voluntarist or Existentialist ideas of taking one's life as one's project.

The followers of the philosopher Mo Zi (or "Mo Tzu" if you prefer the earlier Wade-Giles Romanization) made some early discoveries in optics and other areas of physics, ideas that were consonant with deterministic ideas, but the vine that produced this early fruit quickly withered and died^{[citation needed]}.

A multi-deterministic position

Some determinists argue that materialism does not present a complete understanding of the universe, because while it can decribe determinate interactions among material things, it ignores the souls of conscious beings. By 'soul' in this context is meant an autonomous immaterial agent that has the power to control the body but not to be controlled by the body (this theory of determinism thus conceives of conscious agents in dualistic terms). Therefore the soul stands to the activities of the individual agent's body as does the creator of the universe to the universe. The creator of the universe put in motion a deterministic system of material entities that would, if left to themselves, carry out the chain of events determined by ordinary causation. But the creator also provided for souls that could exert a causal force analogous to the primordial causal force and alter outcomes in the physical universe via the acts of their bodies. Thus, it emerges that no events in the physical universe are uncaused. Some are caused entirely by the original creative act and the way it plays itself out through time, and some are caused by the acts of created souls. But those created souls were not created by means of physical processes involving ordinary causation. They are another order of being entirely, gifted with the power to modify the original creation.

The question of how these immaterial entities can act upon material entities is deeply involved in what is generally known as the mind-body problem. It is a significant problem which has as yet received no answer within the universe of discourse related to the physical universe. The problem has frequently been framed in religious terms: "Is the human soul actually responsible for choices?" René Descartes continues a train of thought that starts at least as early as Duns Scotus and runs through Suarez to affirm that "the will is by its nature so free that it can never be constrained” (Passions of the Soul, I, art. 41). [1]

The question receives a slightly different treatment in Chinese philosophy, beginning with the Mencius. The matter is explicated at some length in D.C. Lau's "Introduction" to his translation of that book, p. 28ff.

Modern perspectives on determinism

Scientific determinism and first cause

Since the early twentieth century when astronomer Edwin Hubble first hypothesized that red shift shows the universe is expanding, prevailing scientific opinion has been that the current state of the universe is the result of a processes described by the Big Bang. Many religionists claim that it therefore has a finite age, and then use this as an attack, pointing out that something cannot come from nothing. The big bang does not describe where the compressed universe came from, instead it leaves it open. Different astrophysicists hold different views about precisely how the universe originated (Cosmogony). A consistent viewpoint is that scientific determinism has always held from the microscopic to the macroscopic.

Determinism and generative processes

In emergentist or generative philosophy of cognitive sciences and evolutionary psychology, free will is the generation of infinite behaviour from the interaction of finite-deterministic set of rules and parameters. Thus the unpredictability of the emerging behaviour from deterministic processes leads to a perception of free will, though free will as an ontological entity does not exist.

As an illustration, the strategy board-games chess and Go have rigorous rules in which no information (such as cards' face-values) is hidden from either player and no random events (such as dice-rolling) happen within the game. Yet, chess and especially Go with its extremely simple deterministic rules, can still have an extremely large number of unpredictable moves. By analogy, emergentists or generativists suggest that the experience of free will emerges from the interaction of finite rules and deterministic parameters that generate infinite and unpredictable behaviour. Yet, if all these events were accounted for, and there were a known way to evaluate these events, the seemingly unpredictable behaviour would become predictable.

Dynamical-evolutionary psychology, cellular automata and the generative sciences, model emergent processes of social behaviour on this philosophy, showing the experience of free will as essentially a gift of ignorance or as a product of incomplete information.

Arguments against determinism

Argument from morality

Some critics of determinism argue that if people are assumed incapable of independent choice (free will) there can then be no rational basis for morality, and therefore some aspects of criminal and civil jurisprudence and legislation appear irrational and unjust. How, they ask, can one be punished for an involuntary action? In order to maintain the integrity of social institutions that rely in part upon holding people responsible for their actions, it becomes necessary in their eyes to deny determinism, at least as far as it applies to what we ordinarily call voluntary actions.

Determinists have responded to this critique by distinguishing between normative and positive claims, arguing that statements of fact can and should be made independently of their consequences. Thus, even if determinism is inconsistent with the idea of a moral universe, that does not necessarily invalidate its conclusions. The presumed social utility of ideas of crime and justice should not be permitted, they argue, to override questions of truth.

American philosopher Donald Davidson, among others, has argued that if people behaved in an uncaused way then one would describe their actions as insane, not as free. His view is consonant with the philosophical position advocated by Mencius that maintains that one's innate characteristics are the result of deterministic causation, that among these innate characteristics there exists a set of drives (analogous to other drives such as the sex drive) that are axiological or moral in nature, and that factors external to these moral drives can act to inhibit their operation. Inhibiting their action is tantamount to a loss of freedom, which is something one instinctively seeks to avoid. In Western terms, Mencius would say that human beings are born with a conscience, that they are acting in accord with their own natures and inclinations when they guide their actions by their consciences (along with their other drives such as hunger), and that we all experience a loss of freedom when we realize that we are being controlled either directly or indirectly by outside forces -- whether those forces are the lingering effects of conditioning or the imminent threat of death posed by a pistol held to one's head. In short, self-determination is freedom and other-determination is loss of freedom. Morality depends on the exercise of what one's nature has determined one to be and on being de facto responsible for all the consequences of what one decides to do. If one is free of external control one is an entelechy; to the extent that one becomes determined by external factors, one loses one's individual identity and becomes merely the extension of another entity.

Determinism, quantum mechanics and classical physics

Since the beginning of the 20th century, quantum mechanics has revealed previously concealed aspects of events. Newtonian physics, taken in isolation rather than as an approximation to quantum mechanics, depicts a universe in which objects move in perfectly determinative ways. At human scale levels of interaction, Newtonian mechanics gives predictions that in many areas check out as completely perfectible, to the accuracy of measurement. Poorly designed and fabricated guns and ammunition scatter their shots rather widely around the center of a target, and better guns produce tighter patterns. Absolute knowledge of the forces accelerating a bullet should produce absolutely reliable predictions of its path, or so we thought. However knowledge is never absolute in practice and the equations of Newtonian mechanics can exhibit sensitive dependence on initial conditions, meaning small errors in knowledge of initial conditions can result in arbitrarily large deviations from predicted behavior.

At atomic scales the paths of objects can only be predicted in a probabilistic way. The paths are not exactly specified in a full quantum description of the particles. The quantum development is at least as predictable as the classical motion, but it describes wave functions that cannot easily be expressed in ordinary language. In double-slit experiments, electrons fired singly through a double-slit apparatus at a distant screen do not arrive at a single point, nor do they arrive in a scattered pattern analogous to bullets fired by a fixed gun at a distant target. Instead, they arrive in varying concentrations at widely separated points, and the distribution of their hits can be calculated reliably. In that sense the behavior of the electrons in this apparatus is deterministic, but there is no way, to predict where in the resulting interference pattern an individual electron will make its contribution (see Heisenberg Uncertainty Principle).

Some people have argued that in addition to the conditions humans can observe and the rules they can deduce there are hidden factors or hidden variables that determine absolutely in which order electrons reach the screen. They argue that the course of the universe is absolutely determined, but that humans are screened from knowledge of the determinative factors. So, they say, it only appears that things proceed in a merely probabilistically determinative way. Actually, they proceed in an absolutely determinative way. Although matters are still subject to some measure of dispute, quantum mechanics makes statistical predictions that would be violated if some local hidden variables existed. There have been a number of experiments to verify those predictions, and so far they do not appear to be violated although many physicists believe better experiments are needed to conclusively settle the question. See Bell test experiments. It is, however, possible to augment quantum mechanics with non-local hidden variables to achieve a deterministic theory that is in agreement with experiment. An example is the Bohm interpretation of quantum mechanics.

On the macro scale it can matter very much whether a bullet arrives at a certain point at a certain time, as snipers and their victims are well aware; there are analogous quantum events that have macro- as well as quantum-level consequences. It is easy to contrive situations in which the arrival of an electron at a screen at a certain point and time would trigger one event and its arrival at another point would trigger an entirely different event. (See Schrödinger's cat.)

Even before the laws of quantum mechanics were fully developed, the phenomenon of radioactivity posed a challenge to determinism. A gram of uranium-238, a commonly occurring radioactive substance, contains some 2.5 x 10²¹ atoms. By all tests known to science these atoms are identical and indistinguishable. Yet about 12600 times a second one of the atoms in that gram will decay, giving off an alpha particle. This decay does not depend on external stimulus and no extant theory of physics predicts when any given atom will decay, with realistically obtainable knowledge. The uranium found on earth is thought to have been synthesized during a supernova explosion that occurred roughly 5 billion years ago. For determinism to hold, every uranium atom must contain some internal "clock" that specifies the exact time it will decay. And somehow the laws of physics must specify exactly how those clocks were set as each uranium atom was formed during the supernova collapse.

Exposure to alpha radiation can cause cancer. For this to happen, at some point a specific alpha particle must alter some chemical reaction in a cell in a way that results in a mutation. Since molecules are in constant thermal motion, the exact timing of the radioactive decay that produced the fatal alpha particle matters. If probabilistically determined events do have an impact on the macro events, such as whether a person who could have been historically important dies in youth of a cancer caused by a random mutation, then the course of history is not determined from the dawn of time.

The time dependent Schrödinger equation gives the first time derivative of the quantum state. That is, it explicitly and uniquely predicts the development of the wave function with time.

File:Schrödinger time dependent.jpg

So quantum mechanics is deterministic, provided that one accepts the wave function itself as reality (rather than as probability of classical coordinates). Since we have no practical way of knowing the exact magnitudes, and especially the phases, in a full quantum mechanical description of the causes of an observable event, this turns out to be philosophically similar to the "hidden variable" doctrine.

According to some, quantum mechanics is more strongly ordered than Classical Mechanics, because while Classical Mechanics is chaotic, quantum mechanics is not. For example, the classical problem of three bodies under a force such as gravity is not integrable, while the quantum mechanical three body problem is tractable and integrable, using the Faddeev Equations. That is the quantum mechanical problem can always be solved to a given accuracy with a large enough computer of predetermined precision, while the classical problem may require arbitrarily high precision, depending on the details of the motion. This does not mean that quantum mechanics describes the world as more deterministic, unless one already considers the wave function to be the true reality. Even so, this does not get rid of the probabilities, because we can't do anything without using classical descriptions, but it assigns the probabilities to the classical approximation, rather than to the quantum reality.

Asserting that quantum mechanics is deterministic by treating the wave function itself as reality implies a single wave function for the entire universe, starting at the big bang. Such a "wave function of everything" would carry the probabilities of not just the world we know, but every other possible world that could have evolved from the big bang. For example, large voids in the distributions of galaxys are believed by many cosmologists to have originated in quantum fluctuations during the big bang. (See cosmic inflation and primordial fluctuations.) If so, the "wave function of everything" would carry the possibility that the region where our Milky Way galaxy is located could have been a void and the Earth never existed at all. (See large-scale structure of the cosmos.)

First cause

Intrinsic to the debate concerning determinism is the issue of first cause. Deism, a philosophy articulated in the seventeenth century, holds that the universe has been deterministic since creation, but ascribes the creation to a metaphysical God or first cause outside of the chain of determinism. God may have begun the process, Deism argues, but God has not influenced its evolution. This perspective illustrates a puzzle underlying any conception of determinism:

Assume: All events have causes, and their causes are all prior events. There is no cycle of events such that an event (possibly indirectly) causes itself.

The picture this gives us is that Event A_N is preceded by A_N-1, which is preceded by A_N-2, and so forth.

Under these assumptions, two possibilities seem clear, and both of them question the validity of the original assumptions:

(1) There is an event A₀ prior to which there was no other event that could serve as its cause.

(2) There is no event A₀ prior to which there was no other event, which means that we are presented with an infinite series of causally related events, which is itself an event, and yet there is no cause for this infinite series of events.

Under this analysis the original assumption must have something wrong with it. It can be fixed by admitting one exception, a creation event (either the creation of the original event or events, or the creation of the infinite series of events) that is itself not a caused event in the sense of the word "caused" used in the formulation of the original assumption. Some agency, which many systems of thought call God, creates space, time, and the entities found in the universe by means of some process that is analogous to causation but is not causation as we know it. This solution to the original difficulty has led people to question whether there is any reason for there only being one divine quasi-causal act, whether there have not been a number of events that have occurred outside the ordinary sequence of events, events that may be called miracles. The extreme philosophical position in this line of development was held by Leibniz, who held in his monistic philosophy that all seemingly causal interactions between two (or more) entities, A <-> B, are actually interactions mediated by God, A<->God<->B.

The other possibility is that the "last event" loops back to the "first event" causing an infinite loop. If you were to call the Big Bang the first event, you would see the end of the Universe as the "last event". In theory, the end of the Universe would be the cause of the beginning of the Universe. You would be left with an infinite loop of time with no real beginning or end. This theory eliminates the need for a first cause, but does not explain why there should be a loop in time.

Immanuel Kant carried forth this idea of Leibniz in his idea of transcendental relations, and as a result had a profound effect on later philosophical attempts to sort these issues out. His most influential immediate successor, a strong critic whose ideas were yet strongly influenced by Kant, was Edmund Husserl, the developer of the school of philosophy called phenomenology. But the central concern of that school was to elucidate not physics but the grounding of information that physicists and others regard as empirical. In an indirect way, this train of investigation appears to have contributed much to the philosophy of science called logical positivism and particularly to the thought of members of the Vienna Circle, all of which have had much to say, at least indirectly, about ideas of determinism.

External links

Stanford Encyclopedia of Philosophy entry on Causal Determinism
Determinism in History from the Dictionary of the History of Ideas
Philosopher Ted Honderich's Determinism web resource
An Introduction to Free Will and Determinism by Paul Newall, aimed at beginners.
The Society of Natural Science

References

Albert Messiah, Quantum Mechanics, English translation by G. M. Temmer of Mécanique Quantique, 1966, John Wiley and Sons, vol. I, chapter IV, section III.
A lecture to his statistical mechanics class at the University of California at Santa Barbara by Dr. Herbert P. Broida [2] (1920-1978) (a well known experimental physicist)
"Physics and the Real World" by George F. R. Ellis, Physics Today, July, 2005 — This article seems to make the common error of thinking quantum probability goes on in nature; but its explanation, in terms of homeostasis, of why life is understandable in terms so different from those of microscopic physics is relevant to the distinction between physical and moral determinism.