A quantum impact on the Free Will-Determinism Debate--Metaphysics version
For four centuries prior to 20th, the Free Will-Determinism debate was seemingly headed for a resolution on the side of Determinism. The primary impetus for this solution was the materialistic philosophies that derived from and were supported by physicists’ explanations of the world. This “Classical” view experienced a great upheaval in the beginning of the 20th century with the advent of Quantum Mechanics and Theories. The seemingly intrinsic indeterminacy of Quantum Mechanics has lead to a review, if not a toppling of power, in the Free Will-Determinism debate. I propose to give a brief overview of the Classical Mechanics/Determinism dynamic, the main Quantum theories, their implications for Free Will-Determinism debate, and demonstrate how orthodox quantum theory provides the possibility for free will
The Classical Mechanics/Determinism dynamic has examples par exemplar in the relationship between Newtonian Mechanics and Laplacian Determinism. This relationship is best explained by the “Laplacian Daemon”:
An intelligence knowing at any given instant of time, all forces acting in nature, as well as the momentary positions of all things of which the universe consists, would be able to comprehend the motions of the largest bodies of the world and those of the smallest atoms in one single formula, provided it were sufficiently powerful to subject all data to analysis; to it nothing would be uncertain, both future and past would be present before its eyes.
(O’Murchu 2004, 26)
The Laplacian daemon by his ability to predict future states and extrapolate past states illustrates epistemological determinism, generally the best metaphysical explanation of which is metaphysical determinism. And with the extraordinary success of Newtonian Mechanics (a mathematically deterministic system) to predict the movement from the smallest terrestrial to the greatest celestial objects it was expected that the development of finer and finer mathematical formulae would end in the ability to show that epistemological determinism was the case. Leading to the Laplacian determinism supposition that the world is metaphysically determined.
If the world is governed by metaphysical and epistemological determinism then it seems that there can not be any free will in the common sense (senses of free will are discussed later). This is the case as in such a world one would have no other choice but to perform all actions in certain orders and ways; actions which epistemological determinism says can be predicted. This view is a boon to materialists, as they can show the world is best explained as causally closed, if the classical view is the case. No soul would be needed to explain human actions and mind/body cause/effect.
Two arguments against the classical view are the self-predictability problem and Chaos theory. Neurobiologist Donald MacKay argued that even if a Laplacian daemon existed, it could not tell someone about their future actions without affecting the person’s behaviour and future actions, thus the daemon could not inform the person if it wished to maintain predictability/epistemological determination. So the person still maintains the illusion of free will (Davies 1983, 136). Chaos theory suggests that infinitesimally small differences in the starting conditions of some classical mathematically deterministic systems could produce drastic variations in their outcomes. This leads some to question the epistemological deterministic element of the classical view. Both of these objections seem weak, and half-hearted. The illusion of free will is not free will, and a mathematically deterministic system is still mathematically deterministic regardless of its outcomes.
So we are forced to accept the materialist’s soulless body and freedomless world. Or are we? In the 1920s a scientific revolution occurred, opening the doors once again to free will and dualism. Quantum Mechanics was started by Schrödinger and Heisenberg, and Quantum Theories began to be formed. The three most influential of which are the Copenhagen, Many Worlds and Bohmian interpretations. I will discuss the Copenhagen interpretation, and briefly mention the views of the Many Worlds and Bohmian interpretations.
The Copenhagen interpretation is considered the orthodox view and is most widely supported by physicists. Two of its distinctive features are its view that quantum mechanics is inherently indeterministic and that systems are observer dependant. The indeterminacy is due to the relationship between the moments before and at the time an observation of the system is made. Prior to observation, a system is considered to be following the deterministic “Schrödinger” dynamic. Schrödinger used wave equations to describe this system that exists in a superposition, where any and all possible outcomes are represented (though interpretations of the equations vary as to whether it is a physical, instrumental or statistical wave). At the time of observation, the system is said to exhibit the “collapse” dynamic, where only one outcome is present. The indeterminacy arises from the “discontinuous, random ‘jump’” from the Schrödinger to the collapse dynamic. This indeterminacy exists if the Schrödinger wave equation has a minute length or a length that spans light years.
One common fallacy in determining the part of Quantum Mechanics that introduces indeterminacy is assumption that the Heisenberg Uncertainty Principle (UP) is the source. The UP stated in a simple form is that we can not know both the momentum or location of a particle. This is commonly interpreted as being due to the wave/particle duality of all objects, where the wave aspect represents a *probability* of the particle’s location. This probabilistic interpretation is not necessarily the case, as the UP could simply be an epistemic limit on what we can know about any object. It could be the case that despite our inability to access this information, it actually exists, and follows deterministic principles.
Observer dependence is the idea that without an observer, a quantum state remains in a superposition of all the possible states that it could be in. That is, if a ball can be red or blue, then without an observer to say it is either red or it is blue, then the ball is said to have both properties at the same time, it is both all red and all blue (the superposition). This proposition is best exemplified by the double slit experiment, in which an observer can determine the behaviour of a particle by the act of observing. The setup of the experiment is as such: a single photon emitting light source is separated from a detector by a barrier with two parallel slits. If the observer chooses TO NOT observe which slit the single photon goes through, then the photon’s behaviour is displayed by the detector as an interference pattern, thus the single photon is said to have existed in a superposition of all possible states. If the observer chooses TO observe which slit the single photon goes through, then the photon’s behaviour is displayed by the detector as a point, thus the single photon is said to have existed in only one particular state due to the observation.
In response to this observer dependence, the Many Worlds interpretation was postulated and is the second most widely held view by physicists. Many Worlds is considered deterministic and non-observer dependant (in one respect). In this view, the collapse dynamic is replaced by all possible states becoming actualised, though in various parallel worlds. Thus “we” happen to be in one of the worlds where a given state is actualised. So in one regard, the actualisation is non-observer dependant, as all possible states are actualised, but in another regard, it is observer dependant in the metaphysical sense, as “we” (“we” being defined as the version of ourselves that have experienced all actualised states in the way we perceived the states to be actualised.) experience a particular world. This view gets very muddled when interpreted into philosophy, and as such many physicists who utilise this view take this to be a purely instrumentalist method, and not an actual metaphysical thesis about the real world.
The Bohmian view is a deterministic view of quantum mechanics utilising what is commonly called pilot waves (though an updated version). The unique feature of these waves, termed the quantum potential by Bohm, is their non-local influence. Non-locality is generally considered a violation of the speed of light, leading to possible causes that occur after their effects, calling into question if causality is the case. However, Bohmian mechanics claims it does not violate causality and is considered empirically equivalent to the Copenhagen interpretation.
As can be seen there are varied views on how to interpret quantum mechanics, so it can only be said to provide an opening for free will, and a very possible closing for universal metaphysical determinism. (Many worlds doesn’t seem meaningfully deterministic, and Bohmian mechanics utilises constructs that most physicists would shy away from except for instrumentalist usages). But what is the relationship between free will and determinism?
Epistemic determinism seems to best be explained by metaphysical determinism, and seems to exclude the outside agent needed for metaphysical free will. True epistemic indeterminism seems to also deny possibility of an outside agent choosing an action, as in a fully epistemologically indeterministic system one would expect to have randomness rule the behaviour of everything even “free agents” i.e., humans, and thus the causality required for an agent to have “freely chosen” an action breaks down, though the system could be metaphysically determined based off of some principle that is not epistemologically determined. Some amount of metaphysical indeterminism seems to be needed for the presence of free will in the common sense. Even complete metaphysical indeterminism seems to be consistent with all agents being free, though this seems to be a bizarre possible world. So for free will to exist in a system it seems to necessitate a few things, the system must not be either fully epistemologically deterministic or indeterministic, and the system must not be fully metaphysically deterministic, with the common sense of free will also excluding the worlds that are completely metaphysically indeterministic. As can be seen this relationship is at times blurry, depending up the form of determinism being talked about.
Let us now look at our understanding of free will and then try to determine some of the implications which quantum theory brings to it. What is free will? Free will in general is understood to be demonstrated by a voluntary action (or inaction) which the agent freely chooses to participate in. Let us look at a few interpretations of this, the view intended in this essay (termed the “common” view), and dissenting views.
The common view of free will is best described by self determinism, a form of compatibilism (which says determinism and free will can exist together). Self determinism is the idea that an undetermined agent and causality together lead to free will. I term this the “common” view as this seems to be most compatible with the idea of free will held by the average person who accepts free will as a fact of the matter. Materialistic self determinism appears to fall into infinite regress in that the agent must be prompted by a causal event, then exert influence on the will to generate effort to exert influence to generate effort… ad infinitum until an actual action can occur. But I propose that this is only a problem to the materialistic interpretation of self determinism and not to the dualistic interpretation. In the dualistic interpretation, exerting influence on the will is meaningless, as the will is not a materialistic object (an object occupying space and time). The will is an element of a “spiritual” or incorporeal object which once receiving causal information from the world, requires no infinite regress to act. This is due primarily to the special nature of a spiritual object being absolutely one and without any division, thus not requiring any internal effort to influence any other part of itself. (We may experience the soul as partitioned, but that is a limit placed upon our consciousness by the materialistic essence of a body and brain. In addition, I suspect that an object that is whole can react to an infinite regress of promptings or to a single prompt in an equivalent “time”.)
An alternate form of compatibilism is soft determinism. Soft determinism says free will is not the ability to have chosen differently given the circumstances, but that it is the ability to have chosen differently had the agent willed so (i.e., under a different predisposition of beliefs and desires). (Geirsson 1998, 367 and Wikipedia) An alternate view of soft determinism is that the very act of self deliberation determines an act as free, if the deliberation leads to an action that is intentional and not coerced by an external or internal agent (e.g., brainwashing or disease). (Roberts) The problem with this view seems to be that it promotes an illusory free will, one that though seemingly free, is in fact based upon predispositions, prior experiences and other facets which seem to culminate in a deterministic causality that prevents the agent from acting in any other manner than the way the agent actually acted.
Two other dissenting views are indeterminism and hard determinism, both of which are forms of incompatibilism. Indeterminism is the view held by many quantum physicists, though their view differs significantly from what is commonly called “libertarianism” by philosophers. Indeterminism in the quantum physicists sense is roughly equivalent to chaos or randomness, things are epistemologically indetermined and there is not free will (or at least free will has nothing to do with the issue). This view doesn’t seem have any specific views of the metaphysical notions of free will or determinism. Libertarianism is similar in the belief that things are not completely epistemologically or metaphysically determined, but in contrast to the scientific sense, libertarians hold that there are metaphysically free acts and free will. Hard determinism claims that there are no metaphysically free acts or epistemologically indeterministic events, only metaphysically and epistemologically determined events. These views seem not to be the case, as current scientific theories don’t coalesce into a world of only epistemologically determined events or of a world that permits uncaused events.
Quantum mechanics indeed does not provide for a world of uncaused events, but instead says that there is indeterminacy in regard to which causes are actualised and thus which events occur, from that point the system can and in our experience does behave in a epistemologically deterministic manner. Quantum mechanics also necessarily rejects a uniformly epistemologically determined system; due to the inherent indeterminacy of the collapse dynamic, there are “uncaused” causes to the limited extent that which causes are actualised are “random”. It is this indeterminacy that seems to provide the possibility of free will. There doesn’t seem to be any theoretical conflict with a free agent deciding which of the states a superposition falls into, as all are possible. Thus this cause/effect chain seems a reasonable method for a free agent to affect free will. But as we will discuss later, this also will seemingly require it to be an external agent.
The first argument against quantum effects being significant metaphysically derives from the very nature of the collapse dynamic. The state which the collapse dynamic acutalises is completely random. And so far as states are not random they are deterministic. And if something is random or deterministic, then there can be no rational free will decision involved. Philosopher David Chalmers argues that “[T]he theory [that quantum indeterminacy allows free will] contradicts the quantum-mechanical postulate that these microscopic ‘decisions’ are entirely random..” (Barr 2003, 180). The essence of this argument is that the free will agent loads the dice, and changes the event from a random one to a predetermined one. Physicist Stephen Barr says this is an “unnecessarily restrictive” view of quantum mechanics. He insists that “if quantum theory says two outcomes are equally probable, that can be interpreted simply as meaning that there is nothing in the physical situation itself that prefers one outcome to the other” (Barr 2003, 180). This does not exclude non-physical agents acting upon the system, though without such non-physical agents the system would be governed by simple probability. Chalmers continues his argument by insisting that if free will did affect physical systems we would expect to see detectable patterns. Which is precisely what we do observe in human behaviour. Barr argues that such patterns are neither so exact that they can be defined in terms of a mechanical law nor so erratic that they are completely random (Barr 2003, 180).
Another argument against quantum effects being of a concern for metaphilosophical discussion is the “classical” limit. The idea of a classical limit is the point where the indeterminacy of quantum theory stops and the determinacy of a classical system takes over. Schrödinger proposed the necessity of one in his classic Schrödinger cat gedankenexperiment via reductio ad absurdum. He stated his argument as such:
A cat is penned up in a steel chamber, along with the following diabolical device (which much be secured against direct interference by the cat): in a Geiger counter there is a tiny bit of radioactive substance, so small, that perhaps in the course of one hour one of the atoms decays, but also with equal probability, perhaps none; if it happens, the counter tube discharges and through a relay releases a hammer which shatters a small flask of hydrocyanic acid. If one has left this entire system to its self for an hour, one would say the cat lives if meanwhile no atom has decayed. The first atomic decay would have poisoned it.
(Davies 1987, 29)
The standard Quantum view of the cat in this enclosed box is that it must exist in the superposition of being both alive and dead, until an observer opens the box. It is only at this point that the cat snaps into one of the two states, it is either definitely alive or definitely dead, but this seems absurd! In fact, if you place a new box around the observer, the cat remains in the superposition until another observer observers the first, and this continues into an infinite regression of observers needing observing for the system to collapse. From this it is generally viewed that at some macro level the effects of quantum indeterminacy ends (though at what point is uncertain), and many view the brain to be immune in a practical way at least from such effects. Though this is itself unclear.
Physicist/Mathematician Roger Penrose (who objects to free will) and Neurophysiologist Sir John Eccles posit locations where quantum effects would affect the brain’s functions. Penrose suggests “‘microtubules,’ in the ‘cytoskeletons’ of the brain’s neurons” while Eccles alternatively suggests, the “presynaptic vesicular grid” (Barr 2003, 183). Though other relevant structures might be so inconspicuous and small that they may never be discovered, and if they are, they may never be recognised as such. In fact, it is not even clear that such specialised spots are needed for quantum effects to influence the brain (Barr 2003, 183).
These suggestions seem to counter any claim that the classical limit is reached in the functions of the brain, and perhaps suggest the necessity of a dualistic philosophy to account for the consistency of causality in our actions. Without an external mechanism to decide which state the superposition of a particle is to fall into, our actions would be chaotic and inconsistent, causality and any hope for an illusion of choice, predictability or genuine free will would devolve into an irrational hope for benign randomness. In fact it would seem that an external agent would be able to maintain the consistency of our actions and to solve the infinite regression of the Schrödinger cat problem without need of a classical limit. By being an observer outside of the physical system, the external agent (a soul) would be able to collapse the system, without being caught in the infinite regression that all physical observers are subject to. What exactly is the way that the soul would affect the collapse in the way it wants? I am unsure, though it seems that this could simply defined as a property of the soul, which seems a stopgap solution.
I have given an overview of the classical dynamic, the main quantum theories and their implications for the Free Will-Determinism debate and demonstrated how orthodox quantum theory provides the possibility for free will. Orthodox quantum theory seems to open the door for free will and then dualism, as free will seems to require indeterminacy, and quantum indeterminacy seems to require an external observer to collapse the system into a particular state. This is not to say that the quantum mechanics necessitates this interpretation, as there are various other interpretations only a few of which I’ve mentioned in this essay.
posted by sirhair @ 12:34 AM
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