Quantum retrocausality may give us free will
Recent arguments in favor of retrocausality (the ability for a cause to happen after its effect) come from the time-symmetry of quantum…
Recent arguments in favor of retrocausality (the ability for a cause to happen after its effect) come from the time-symmetry of quantum mechanics. Since all processes that happen in one direction in time are time reversible, then effect must necessarily be able to preceded cause no matter how unlikely.
This means a person could actually make a choice that causes their past.
There is no reason to believe that the past is actually fixed and the future is not. It may be just as likely that they are both unfixed as fixed and that the past that we remember in our brains, books, computers, and so on is more of a set of information that is continually being updated with previously undetermined facts as we make choices.
Because of classical determinism, however, it is likely that both past and future are fixed except in those cases where there is a quantum superposition of states such that reality is unobserved and hence undetermined. When cause happens after effect in this way, it may throw a monkey wrench in certain free will arguments.
Free will is defined as having the power to choose otherwise, all things being equal. In other words, does anything I do affect the future and if so could I choose to do something other than what I did choose?
Let’s look at the history of free will arguments, which are largely part of the philosophy of ethics, since it relates to moral responsibility for our actions. Christian theologians, particularly during the Protestant reformation, had the most to say on free will until the advent of modern philosophy, and I will mention a few of their arguments as well.
Most arguments over free will today take one of three basic approaches:
All is predetermined. Free will is an illusion and humans aren’t responsible for their actions.
All is predetermined. Free will is part of that and humans are responsible for their actions.
All is not predetermined. Free will changes reality from moment to moment.
The first is called incompatibilism to distinguish it from the second, compatibilism. The third is a more common understanding of free will in that our intuition is correct, and we really do make choices.
Most philosophers are either incompatibilist or compatibilist. The third option is widely recognized as being ill-defined because human beings make decisions with their brains. Brains obey the laws of physics which are either deterministic or random. It is impossible to hold to the 3rd option without appealing to some non-physical source for will.
An incompatibilist belief system means that I believe that I have no power to choose otherwise. The universe or God has chosen for me.
The Calvinist or Reformed theology is an incompatibilist point of view in which God preordains people for salvation or damnation. We have no control.
Why God would hold us responsible for actions that were His and not ours doesn’t make a lot of sense to me. Even worse, why would God choose for us to do evil instead of good?! The Bible clearly suggests that humans choose to do evil and are morally responsible, so I don’t know how this ever became a popular idea.
Most philosophers, unlike the Calvinists, believe that incompatiblism implies we are not responsible for our moral decision making and that the justice system should focus on rehabilitation of criminals, as if they were malfunctioning automata. Scandinavian nations take this approach with their prison system, while the United States takes a retributive attitude.
A compatibilist belief system means reconciling determinism with free will. It attempts to attack the “consequence” argument of incompatibilists:
No one has power over the facts of the past and the laws of nature.
No one has power over the fact that the facts of the past and the laws of nature entail every fact of the future (i.e., determinism is true).
Therefore, no one has power over the facts of the future.
The classical argument for compatibilism says that we can control our actions but not our desires, so even though we have the power to do otherwise, we do not have the desire. If the past were different than it is, we might have desired something else and done something else. This is all the freedom we get.
Luis de Molina, a 16th century Jesuit theologian, took this point of view and today adherents are called Molinists. In this case, God has preconditioned the past knowing what decisions we will make under any conditions (this is called “middle knowledge”); so he has arranged the universe so we will freely choose what he ordains. In this case, we are responsible for our actions and our own salvation or damnation, but we will choose one or the other based on the preconditions God has set for us. It is hard to guess why God would arrange the universe this way. It does away with God having responsibility for evil, unlike the Calvinist view, but it suggests that God could not or would not create a universe where people are not evil, despite determining all the conditions for its creation and knowing all the choices people would make under any circumstances.
The best way to think of the compatibilist viewpoint is to imagine a multiplicity of worlds in which you exist but have different pasts. In each world you make different choices and have different outcomes. Thus, you have the ability to freely choose in each one, yet each one is uniquely and precisely determined.
You only get to live one world but this is an illusion.
A Many Worlds quantum philosopher such as Sean Carroll, would even say that all of them exist simultaneously.
Whether these other worlds, sometimes called counterfactual worlds because they are counter to the reality we live in, exist or not, their hypothetical existence gives us free will because we would have the power to choose otherwise if the past were different.
As an example, if a person has a terrible upbringing, it doesn’t excuse them from committing crimes as an adult, no matter what the abuse they suffered.
An incompatibilist can acknowledge all this, however, and say that none of this is compatible with a definition of free will because, no matter what choices we are offered in our world, we will make one and only one choice and we can do nothing else. Thus, our “will” isn’t any will at all. I will get to this argument in a minute.
The third option is a free will belief that holds that determinism, #2 above, is false. When faced with a choice, the future can branch off into many different possible outcomes depending on what choice we make.
This is the position of the Arminian theology, named for Jacobus Arminius, which was a reaction against Calvinism a century later. All people have free will to determine their future and are fully responsible for their actions and the outcomes of their actions. God does not predetermine the future, but only provides opportunities for atonement and salvation. God doesn’t seem quite this hands off in the Bible, but it does help explain why there might be evil if God just rolls the dice and lets the universe do what it wants.
As with compatibilism, people are held morally responsible for their actions and in addition it is assumed that, if a person were to commit a crime, they could have chosen not to commit it all things being equal.
An argument against undetermined free will is that the brain is a product of either deterministic or random physics. Therefore, the brain cannot be the thing making the decisions for them to be undetermined and truly free. In that case, the will must be some supernatural force that exists apart from the brain invoking a dualist philosophy of mind.
These are the three main positions on free will.
The question of free will is an interesting problem because it is at the juxtaposition of ethics and time. Ethics assumes that our moral choices are in linear time with cause preceding effect, but what if our understanding of time is wrong?
The first premise above that no one has power over the facts of the past seems ironclad. Compatibilists have challenged it on the idea that a person faced, in the past, with a choice between A or B, could change what their past would have been in another hypothetical world. For example, if they had chosen A, X would have happened, if they had chosen B, Y would have. Each person, therefore, contains within them the potential to make choices such that the past would have been different. And it is that potential that gives them power over the facts of the past.
I have argued elsewhere that quantum physics makes these counterfactual pasts very real because they are contained within quantum wavefunctions. In any complete interpretation of quantum mechanics, where the wavefunction does not collapse and loses its information, all these counterfactual realities continue to exist for all time in some form. Thus, both outcomes X and Y of the choice between A and B remain within the complete wavefunction.
Entropy in quantum theory suggests also that there are many more futures than pasts for any given state of a system. This creates a time asymmetry and something incompatibilists need to address. If past X can generate futures A, B, and C, that means that #2 above may be false. The future is undetermined, albeit random. That creates a potential opening because it says that not only could a person do A with past X and B with past Y, but they could, by the flip of a quantum coin, make choices A, B, or C all with the same past X.
A time-symmetric, retrocausal interpretation of quantum mechanics suggests this time asymmetry above is, however, an illusion and that at every moment there are an equal number of possible future and pasts that can be determined from one’s choices. All those alternative pasts remain within the wavefunction of the universe, hidden.
Moreover, it is possible that certain quantum phenomena that generate Schroedinger cat states, meaning states that are smeared out across multiple incompatible possibilities, create an indeterminancy in what the past is. For example, if the cat is smeared between life and death, then the past isn’t completely determined. That is fine, of course, because it will be resolved once we observe the state. But what happens if such states are retrocausal, meaning that they are essentially predictions about what will happen but they are indeterminant? This opens up a question about whether our choices can influence the past.
Look at it this way, imagine that you have complete amnesia and you are in a blank room. The only thing in the room is a box. Inside the box are notes and messages to yourself, apparently from the past. You feel compelled not to read the notes while you are in the room.
To leave, you need to make a choice. There are two doors out of the room, a red and a blue one.
You choose the blue one and enter another room. Now you open the box. It says, “you will go through the blue door.”
This is an example of retrocausality. If you had gone through the red door, it would have said, “you will go through the red door.” The superposition of states ensures consistency with your choice.
If our choices affect the past in this way, then it violates #1 above in a very strong way. It means that you do have power over the facts of the past. You may have power over the facts of the past and the future. The only caveat is that you cannot have access the information from the effect in the past until the cause is also past. It may free you, however, from being completely determined by the past because the past isn’t completely determined yet.
If this is true, then our choices may be preconditioned on only those facts about the past that are determined, while those facts of the past that are undetermined may be preconditioned on our choices.
What this means is that given a choice A and B and a past X and Y, our choice A may create past X and choice B create past Y. The choice necessarily arises deterministically, however, from information that is common to both X and Y. Hence, our free choice is simply to choose between X and Y. This tears down the incompatibilist argument because, since all information used to make the choice is common to X and Y, and the choice is to delineate between them, the choice itself cannot be determined by the past. It must be free.
You may wonder how often such a strange choice arises. Is it that the vast majority of the time we are making choices deterministically? Probably yes, but it does show that there may be built within our universe the potential for free choice and that is important.
McKenna, Michael and D. Justin Coates, “Compatibilism”, The Stanford Encyclopedia of Philosophy (Fall 2021 Edition), Edward N. Zalta (ed.), URL = <https://plato.stanford.edu/archives/fall2021/entries/compatibilism/>.