It was God who created humankind in the beginning, and he left them in the power of their own free choice. If you choose, you can keep the commandments, and to act faithfully is a matter of your own choice. He has placed before you fire and water; stretch out your hand for whichever you choose. Before each person are life and death, and whichever one chooses will be given. (Sirach 15.14-17)
So every now and then I see some supposed scientific reason why free will does not exist. This week it is quantum mechanics that supposedly rules out free will (although I’ve more frequently seen quantum mechanics cited as a reason why freedom is an irreducible aspect of the universe). However, let’s say for argument’s sake that there is a way of conceiving the universe as a completely closed system such that, if we know all inputs, we can accurately predict all outputs. In principle, this means all things are determined and there is no free will (no freedom at all in a strong sense). So what are we to make out of these mutually incompatible conclusions that quantum physics can be enlisted to support EITHER determinacy OR indeterminacy?
When we dig deep into all of these articles, we notice they are always speaking about “determinism in principle” rather than determinism in fact. They quickly qualify that there is no way of fully quantifying all inputs. Why does this matter? Since we cannot know exhaustively all inputs, we cannot determine with precision all outputs. In fact, we are so bad at calculating all inputs that we almost always fail to predict outputs meaningfully or accurately, especially when they involve animals of high intelligence and creativity.
BUT— we are told— IF we were able to have a quantum doohickey computer that was able to model all processes exactly without resorting to simplified equations, we could get exact and accurate predictions of any system in the real world. Basically, if we create a system that is as complex as the real world and model it in real time, we can create a parallel copy of the real world.
HOWEVER, if predicting outcomes in the real world requires duplicating exactly the real world, or else accurate outcomes cannot be predicted, isn’t this exactly the same as free will? A truly deterministic system would be one that could be modeled accurately by a less complex mathematical formula, so that you reduce inputs to variables, and plug and chug them, and in a couple of minutes you come up with the exact real world outputs without having to test in the real world. As an example: You can put in the muzzle velocity of a bullet, spin, gravity, wind, and a few other variables, and you know how exactly where the bullet is going without firing the gun. But you cannot predict exactly how history will unfold from 1922 to 2022 without an exhaustive input of ALL the precise starting conditions of everything in the universe in 1922. And then you would have to run it on a simulation that would be at least as complex as the actual universe.
To add to it, a common interpretation of quantum indeterminacy is that even if all the starting conditions are the same, running the system from the start will never yield the same outcome twice. You cannot re-run time and duplicate events exactly in this interpretation. But even if this interpretation is dead wrong, if it takes re-running the entire system in order to get the same results— if there is no way to simplify it and turn it into an algorithmic function— then this is the same as saying the system is radically free and cannot be predicted. To get any state of affairs the system has to be run in total, altogether, or else the results cannot be accurate. Determinism, to be a meaningful concept, must be able to simplify reality and turn it into something like an algorithm where all inputs can be quantified and calculated in the abstract to get accurate and predictive results in the real world.
So, if we say “All of Nate’s actions are predetermined by all of the inputs that have influenced his personal history, such that we cannot predict Nate’s choices except by constructing an exact replica of Nate and the entire universe of causes that surround him”, then the concept “predetermined” becomes meaningless. If the only entity that can accurately predict all of Nate’s choices is a computer with infinite complexity and exhaustive omniscience, then we are saying functionally the same thing as people who claim humans are totally free, and only “God” can know their choices in advance.
So, long story short: I’m pretty sure that chaos and indeterminate freedom are intrinsic to the fabric of reality. But even if this is not exactly the case, and all events and choices are “determined” by the complete sum total of every input into the system in an irreducible complexity, this is effectively the same as saying chaos and freedom are intrinsic to the system. Perhaps I am missing something here, but it seems that a system which cannot be reduced and predicted cannot be meaningfully called “deterministic”.
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