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Why Quantum Mechanics is not an argument against Determinism

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Why Quantum Mechanics is not an argument against Determinism

yasseford
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Posted 07/10/09 - 09:30 AM: Subject: Why Quantum Mechanics is not an argument against Determinism	#1
Arguments against Hard Determinism (that is, that free will is an illusion and all events are causally determined) have been made on the basis of Quantum Indeterminacy. What is Quantum Indeterminacy? It was noted by Werner Heisenberg that one can never accurately measure the momentum and position of an electron, because in order to take a measurement of the position, one would inadvertently alter the momentum the electron, and vice versa. This is not an example of Quantum Indeterminacy, which makes metaphysical claims, but rather this is an epistemic qualm about subatomic particles. In truth, we can never measure the position and momentum of an electron "because electrons do not have simultaneous determinate positions and momentums." On the quantum level, particles behave without cause. Scientists measure things on scales of probabilities, but this is not how one would normally think of probabilities. Conventionally, people will say that a flipped coin has a 50% chance to land on heads, but if the conditions of the architecture of the coin, the atmosphere, the trajectory and velocity of the flip are all taken into account, then "chance" has no part in it, and we can know quite certainly that the coin would have definitely landed on heads (or tails). When we refer to probability in Quantum Mechanics, we are talking about objective probability. This is not a probability based upon epistemic uncertainty due to our inability to know certain variables. The way that subatomic particles behave objectively varies and it is impossible to determine how they will behave. Why does Quantum Indeterminacy supposedly matter in macroscopic events? It would seem that knowing the position and velocity of an electron should have no effect on our daily lives, but this is not true. One could argue that things such as the half-life of a radioactive element, the shining of the Sun, and other events that work off of quantum indeterminacy do affect our lives macroscopically. The argument is that it is the summation of quantum mechanics that make up macroscopic events like you waking up in the morning and choosing what to eat for breakfast. Why QI is not an argument against determinism. Hard determinism opposes free will on several grounds: religious (e.g. a divine power's ability to impose its will); ethical (e.g., moral responsibility); and scientific(every effect has a cause). The implications for either are far reaching, but essentially what we're trying to find out here is whether rational agent A had a choice between carrying out action X or Y, when he carried out action X. Determinism says that he had no choice in carrying out action X, and free will says that he had a choice to carry out action X, and could have chosen to carry out action Y. Now, supposing that QI is true (there is overwhelming evidence by the vast majority of the scientific community to support this), scientifically speaking, not everything that we do is 100% physically caused. There are some aspects of our actions, however minute, which have been suaded indeterminately. But did agent A still have a choice between X or Y? It seems clear that this is not the case, as either action X was carried out as a conclusion of 100% causal chain, or action X was carried out after a combination of a causal chain and the indeterminate behavior of subatomic particles. One could argue that action X is still 100% causal, as QI caused the events that caused action X, and I personally am a proponent of this point. If not, then one must still face the fact that either the choice was caused, or it was the summation of random probability. There was no rationality (or even irrationality) involved, and agent A had no real choice in the matter. Conclusion QI may have some merit as an argument against the scientific implications of determinism, but the religious and ethical implications of determinism still stand, regardless of what QI proves about our world. Quote taken from http://www.uhh.hawaii.edu/~ronald/310/Quanta.htm. For a broader explanation of Quantum Indeterminacy for the layman (such as myself), check out A Briefer History of Time by Stephen Hawking. It's a great read!
Yasseford

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Posted 07/11/09 - 01:21 AM:	#2
I agree with your point, but I think you should reword your conclusion. QI is are argument against determinism. It is just not an argument for Libertarian free will. The two are not exhaustive of the possibilities. This notion of free will requires that determinism be false, but that is not all that it requires. DM
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wuliheron
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Posted 07/11/09 - 11:45 AM:	#3
yasseford wrote: Arguments against Hard Determinism (that is, that free will is an illusion and all events are causally determined) have been made on the basis of Quantum Indeterminacy. What is Quantum Indeterminacy? ... In truth, we can never measure the position and momentum of an electron "because electrons do not have simultaneous determinate positions and momentums." This is a metaphysical claim that cannot be substantiated. Know one really knows why quanta behave the way they do, all we Indeterminacy gives us is a description of what we observe. For all anyone knows quantum weirdness is the result of angels taking tap dancing lessons. yasseford wrote: On the quantum level, particles behave without cause. Scientists measure things on scales of probabilities, but this is not how one would normally think of probabilities. Conventionally, people will say that a flipped coin has a 50% chance to land on heads, but if the conditions of the architecture of the coin, the atmosphere, the trajectory and velocity of the flip are all taken into account, then "chance" has no part in it, and we can know quite certainly that the coin would have definitely landed on heads (or tails). When we refer to probability in Quantum Mechanics, we are talking about objective probability. This is not a probability based upon epistemic uncertainty due to our inability to know certain variables. The way that subatomic particles behave objectively varies and it is impossible to determine how they will behave. There is no single quantum metaphysics that applies to every observation of quanta, this is the same mistake made many people who claim QM proves the existence of God or whatever. For example, in QCD it is possible to have a 100% probability, but this is only possible in QCD theory which only describes quarks. yasseford wrote: QI may have some merit as an argument against the scientific implications of determinism, but the religious and ethical implications of determinism still stand, regardless of what QI proves about our world. I agree with the conclusion, but the reasoning is sloppy and verbose imo. Quantum Mechanics is just a physical theory and it is a mistake to assume that physical theories must reflect some kind of metaphysical reality. This mistake was commonly made by physicists themselves, for example, when Newtonian Mechanics first proved so useful. The results were newcomers and outsiders like Einstein having to change the field and old conservatives like Max Planck begging his colleges to prove his observations wrong! It tends to go with the territory. Despite scientists prizing objectivity they tend to emphasise causality more. Sorry, but you just can't have it both ways every time. Even if the universe is ultimately causal, that is no guarantee that our perspective of it will always appear to be causal.

jsidelko
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Posted 07/11/09 - 04:21 PM:	#4
If the MWI interpretation is correct,the wave function would instantiate in every possible world. This implies an ontic super-determinism for the wave function with an epistemic indeterminism for members of each world.
thanatos

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Posted 07/12/09 - 05:39 AM:	#5
Hi, I'm a newbie. If I understand correctly, quantum mechanics only demonstrates an epistemic indeterminism. However, this epistemic indeterminacy of the quantum substrate of neural processes demonstrates that the agent of any such neural activity in the act of making a choice can never know whether the choice emerged from the macrocosmic neural processes over which they have a degree of control or whether their decision was a product of the summation of indeterminate quantum processes. Is this correct?

yasseford
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Posted 07/12/09 - 06:49 PM:	#6
Death Monkey wrote: I agree with your point, but I think you should reword your conclusion. QI is are argument against determinism. It is just not an argument for Libertarian free will. The two are not exhaustive of the possibilities. This notion of free will requires that determinism be false, but that is not all that it requires. Absolutely true. I'm glad my conclusion was still clear. wuliheron wrote: This is a metaphysical claim that cannot be substantiated. Know one really knows why quanta behave the way they do, all we Indeterminacy gives us is a description of what we observe. For all anyone knows quantum weirdness is the result of angels taking tap dancing lessons. This is an epistemological claim about absolute certainty, of which the same can be said not just of quanta but of all phenomena. My point though, was that physicists claim these quanta behave indeterminantly, not out of the physicists' lack of knowledge of any known cause, but because of objective proof. Don't ask me how on Earth they know this, the details are above my head at the moment, but it was expressly explained to me that these quanta are labeled indeterminate *not* out of epistemic uncertainty. wuliheron wrote: There is no single quantum metaphysics that applies to every observation of quanta, this is the same mistake made many people who claim QM proves the existence of God or whatever. For example, in QCD it is possible to have a 100% probability, but this is only possible in QCD theory which only describes quarks. I was not aware of this. Really interesting. Although I think that, despite this, my point is still clear that physicists are trying to make a distinction between the general use of probability and objective probability. wuliheron wrote: I agree with the conclusion, but the reasoning is sloppy and verbose imo. Quantum Mechanics is just a physical theory and it is a mistake to assume that physical theories must reflect some kind of metaphysical reality. This mistake was commonly made by physicists themselves, for example, when Newtonian Mechanics first proved so useful. The results were newcomers and outsiders like Einstein having to change the field and old conservatives like Max Planck begging his colleges to prove his observations wrong! Can you elaborate on this point? I don't understand why a metaphysical belief cannot be based around physical observation. For example, Bertrand Russel's metaphysical belief that humans hold no inherent importance in the world is based partly upon his belief in the physical model of the universe. (And Ptolemy's geocentric theory, while incorrect, buttressed the Christian view that humans did have inherent importance). Perhaps I'm misunderstanding your point, though. philstilwell wrote: Hi, I'm a newbie. If I understand correctly, quantum mechanics only demonstrates an epistemic indeterminism. However, this epistemic indeterminacy of the quantum substrate of neural processes demonstrates that the agent of any such neural activity in the act of making a choice can never know whether the choice emerged from the macrocosmic neural processes over which they have a degree of control or whether their decision was a product of the summation of indeterminate quantum processes. Is this correct? What I meant to illustrate was that QI doesn't say anything about epistemology (this is the misunderstanding many people have about it, including myself, previously). My main point was that whether or not an agent's actions emerged from "macrocosmic neural processes" or indeterminate quanta, the agent still does not possess Libertarian free will.
Yasseford

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1 of 1 people found this post helpful Posted 07/13/09 - 12:10 AM:	#7
yasseford, My point though, was that physicists claim these quanta behave indeterminantly, not out of the physicists' lack of knowledge of any known cause, but because of objective proof. Don't ask me how on Earth they know this, the details are above my head at the moment, but it was expressly explained to me that these quanta are labeled indeterminate not out of epistemic uncertainty. This is not quite correct. What we have objective evidence of is that quanta behave acausally, but this is not quite the same thing. What we know is that any determistic model of quantum mechanics must be non-local, which rules out the conventional idea of causality, where every event is determined by state of the system in the past. This does not rule out acausal determinism, though, where every event is determined by some set of boundary conditions that need not simply be the state of the system at some point in the past. This mistake is common for a number of reasons, principle among them being that most people don't even realize that there is a distinction between general determinism and temporal causality, and the fact that we often here scientists say things like "quantum mechanics is non-deterministic". But we have to keep in mind that technically speaking, that is a statement about the model, not about reality. It is only a statement about reality to the extent that we claim that this model accurately describes reality. But that does not imply that reality is non-deterministic. Indeed, I would argue that it is a category mistake to try to assign attributes like "deterministic" or "non-deterministic" to reality. The only way we can meaningfully use these terms to describe reality, is in the sense of saying that a deterministic (or non-deterministic) model accurately describes reality. But then it is entirely possible for both types of models to do so. What I meant to illustrate was that QI doesn't say anything about epistemology (this is the misunderstanding many people have about it, including myself, previously). My main point was that whether or not an agent's actions emerged from "macrocosmic neural processes" or indeterminate quanta, the agent still does not possess Libertarian free will. Correct. And if you follow this line of reasoning to its logical conclusion, what this illustrates is that the entire concept of Libertarian free-will is simply incoherent. It essentially amounts to saying "the choice was not deterministic (causally or a-causally), but not random either". This is gibberish. All "random" means is "not deterministic". Either the choice was determined by some set of constraints, or it was not. If it was, then it is not the case that you could have chosen differently given those same contraints. If it was not, then it was not you that ultimately determined what the choice was, because the choice was not determined at all. Of course, the solution for this is simple. And that is to recognize that our informal conception of free-will doesn't really require that my choices be undetermined, but rather that it is I who am making the choices. The mechanism by which I make those choices is another issue entirely. All free-will means to me is that I have a will, and that it is not being controlled by some external agency. This does not forbid determinism, or even randomness, because the laws of physics that my brain functions according to are descriptions of the nature of my brain, not an external agency that somehow "controls" my brain. DM
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yasseford
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Posted 07/13/09 - 04:02 AM:	#8
Death Monkey wrote: yasseford, This is not quite correct. What we have objective evidence of is that quanta behave acausally, but this is not quite the same thing. What we know is that any determistic model of quantum mechanics must be non-local, which rules out the conventional idea of causality, where every event is determined by state of the system in the past. This does not rule out acausal determinism, though, where every event is determined by some set of boundary conditions that need not simply be the state of the system at some point in the past. This mistake is common for a number of reasons, principle among them being that most people don't even realize that there is a distinction between general determinism and temporal causality, and the fact that we often here scientists say things like "quantum mechanics is non-deterministic". But we have to keep in mind that technically speaking, that is a statement about the model, not about reality. It is only a statement about reality to the extent that we claim that this model accurately describes reality. But that does not imply that reality is non-deterministic. Indeed, I would argue that it is a category mistake to try to assign attributes like "deterministic" or "non-deterministic" to reality. The only way we can meaningfully use these terms to describe reality, is in the sense of saying that a deterministic (or non-deterministic) model accurately describes reality. But then it is entirely possible for both types of models to do so. So if a quantum behaves temporally-acausally, that does not say it does not have a cause? Are there any theories as to what causes quanta to behave the way they do? If the physical state of the quantum and/or universe at time X in any way affects its properties at time y, then it must be true that the quantum behaves temporally-causally. This seems to be the case even if the determinate is non-local. But I digress. Death Monkey wrote: Correct. And if you follow this line of reasoning to its logical conclusion, what this illustrates is that the entire concept of Libertarian free-will is simply incoherent. It essentially amounts to saying "the choice was not deterministic (causally or a-causally), but not random either". This is gibberish. All "random" means is "not deterministic". Either the choice was determined by some set of constraints, or it was not. If it was, then it is not the case that you could have chosen differently given those same contraints. If it was not, then it was not you that ultimately determined what the choice was, because the choice was not determined at all. Of course, the solution for this is simple. And that is to recognize that our informal conception of free-will doesn't really require that my choices be undetermined, but rather that it is I who am making the choices. The mechanism by which I make those choices is another issue entirely. All free-will means to me is that I have a will, and that it is not being controlled by some external agency. This does not forbid determinism, or even randomness, because the laws of physics that my brain functions according to are descriptions of the nature of my brain, not an external agency that somehow "controls" my brain. DM In light of the discrepances you have highlighted about QI, it seems that I don't even need to attack QI's claims in order to attack Libertarian free-will. It does seem odd that a model such as Libertarian free will would have so much "merit" in the practical world, from our religions to our court systems, when it seems so mysterious and borders on incoherency. Your solution of course simply redefines Libertarian free-will to mean the same thing as "the will," which does not justify our Libertarian behaviors (eg, holding people accountable for their actions; religious models of universe that require free will, etc).
Yasseford

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Posted 07/13/09 - 07:37 AM:	#9
Death Monkey wrote: And if you follow this line of reasoning to its logical conclusion, what this illustrates is that the entire concept of Libertarian free-will is simply incoherent. It essentially amounts to saying "the choice was not deterministic (causally or a-causally), but not random either". This is gibberish. All "random" means is "not deterministic". Either the choice was determined by some set of constraints, or it was not. If it was, then it is not the case that you could have chosen differently given those same contraints. If it was not, then it was not you that ultimately determined what the choice was, because the choice was not determined at all. Very cogent. Thanks.

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Posted 07/13/09 - 08:49 AM:	#10
yasseford, If you are correct, and all human behavior (as well as all other behavior) is compelled by causes and not by reasons, then my agreement (or disagreement) with you must also be compelled by causes, not reasons. Therefore, you have not presented a compelling argument for your position here. At best, you could say we are forced to agree with you by some determinate or indeterminate physical process and not by logic, evidence or the force of reason. Of course, philosophical debate becomes quite pointless, too, so I would question the value of your remarks, even if I couldn't dispute it's truth... but what would be the point, right? What the debate seems to me to be missing is that reasons ARE causes, brought about by animals with sufficient brain-matter to reason about their own behaviors. "Choice" for humans, is simply that: reasoning to the best possible outcome of various behaviors. It's not "free" in the sense that it could be anything or that it has no causal antecedents. But it is not explained by sub-atomic particles or quantum mechanics, either. The operation of reason is an advanced neurological function, neurons being composed entirely of carbon and a few other elements in the periodic table. Whether nature is deterministic or non-deterministic in it's smallest parts it quite irrelevant to the operation of brains as they consider alternative choices. All reasons are causes but not all causes are reasons. Therefore, to frame the argument as a dilemma between random probablilty (causes) and ratinality (reasons) is mistaken. A reason is a special kind of cuase or selection process that relies on advanced neurological functions, rather than random probablities. Will is still not "free", in the sense of uncaused. It is compelled, more or less, by reason or desire, depending on the moral character of the human agent and its ability to to consider and choose most wisely. That's what makes the individual morally responsible for their behavior.

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