A common misconception surrounding the free will debate is the idea that if we can’t predict the future, that free will somehow resides or has the possibility of residing in the fact that we can’t know such. That somehow our lack of being able to know all of the variables is the savior of free will.
This misconception is often grounded by the ways words such as “determinism” are not used for the free will debate. People tend to look at such words and assume what is being suggested by the word is that “we” can determine what we will do in the future. And when they hear about things such as the uncertainty principle, or about a measurement problem (there are different ones), or even chaos theory, they note that we can’t “determine” the future in any absolute way, and so (they believe) such “determinism” doesn’t apply.
But this is not the way such words are used for the free will debate. Rather, determinism just means is that each event that takes place in the universe has a cause. In other words, every event is “determined” by some other event that leads to it. This says absolutely nothing about our capacity to actually determine (or know) what will happen in the future. In fact, our inability to predict the future is completely irrelevant to our understanding of why free will, defined here, is logically impossible.
This misunderstanding also stems back to Laplace’s demon, a thought experiment derived by Pierre-Simon Laplace in 1814 in which he wrote about a hypothetical intellect that, if at a certain moment, could know all of the forces, positions, and motion of everything – would be able to predict the future based on those variables. And though the thought experiment is quite helpful in understanding how a fully causal universe would work, people seem to mistake this to mean that if one cannot have, even in theory, those predictive capabilities, that such leaves room for free will. This, however, is anything but the case.
Free will simply isn’t found in our incapacity to now know all of the variables, or in our incapacity to predict some future events. It is true that if we could know exactly what a person will do at each moment, that such means that person isn’t free to do otherwise. But this is not needed to assess the lack of free will.
Rather, what is needed is an understanding of causality, or for those who postulate that the universe has some indeterminism, an understanding of both causality and acauasality (events without causes). And, if we cared to, we can look at what such events imply without ever addressing whether we could or could not predict future events – at all!
In fact, if the universe is entirely causal (deterministic), we can accept that such events could be so chaotic that predicting with certainty for some things would be impossible. Chaos theory means that a small change can lead to a large result, even in a short amount of time.
Or we can accept that at the quantum scale, things are just too small to measure to assess an outcome. One can think of this type of measurement problem with an analogy:
Imagine we place a thermometer in a tub full of water. We can get a fairly accurate reading of the temperature of that water. Now imagine we have a small vial of water that a thermometer just fits into. The very act of placing the thermometer in that vile of water causes the temperature of the water to change as the thermometer itself distributes its own heat. For the small amount, the very act of measuring means that the device that is measuring must interact and change the very thing we are trying to measure.
In quantum mechanics, to interact with a particle, one needs to measure such with an interaction of other particles of a similar size. This, of course, will change what we are trying to measure. This causes a measurement problem, as to detect particles of such a small-scale we need to interact with them in a way that has an effect on the particle itself.
Or depending on the quantum interpretation we postulate, the variables might be “out of sight” or “hidden”, for example with a many worlds or hidden variable interpretation. For a hidden variable interpretation, the variables may be “non-local”, meaning action at a distance. These are all things we most likely cannot measure to create a prediction.
Or we can address the uncertainty principle where we cannot measure both the momentum and position of a particle simultaneously with accuracy. When we measure one, the other becomes “blurred”. The reason for this depends on the quantum interpretation being postulated, which can be either deterministic or indeterministic.
And if we address a particle being in superposition, we may not be able to know the outcome (the property that will come about) upon measurement. All we can know is it will be one of the superpositioned states.
In regards to indeterministic models, we cannot predict the future because we can never assess an acausal event. Such an event would have no spatial or temporal determinacy, meaning we can’t know where or when it will take place, or if it will take place at all (this has problems for other reasons that we will not get into here).
All of these reasons means that we cannot predict the future with absolute accuracy, or at the very least it means us ever being able to is quite unlikely. That is not to say we cannot make predictions at all. Science does this all the time with some astounding proficiency. We simply cannot know where every particle is or will be at all times, which is different from large-scale assessments (e.g. we can assess fairly accurately that the Earth will keep rotating and we will see daylight tomorrow).
But again, our incapacity to predict every event simply does not imply that we cannot assess if free will is possible, and discover it’s not. We don’t need to be able to predict the future. All we need to understand is what it means that an event must either come about via a cause, or be an acausal event. Both of these ways leave free will in the realm of nonsensical fiction.
For causes, each event stems back to other events, which stem back to other events. These events stem further in time, prior to our very own birth. For acausal events, such can never be considered a “willed” event, as the very idea of coming from a “willer” means the event is causal (caused by a willer or part of a willing process). And any interplay between causal and acausal events are outside of our control, as we have no say on how an acausal event arises or interact causally once it exists in the world. No matter how we slice or dice events, or how complex the setup is, there is nothing that can give rise to free will.
But the above is the quick simplistic version of the reasons why free will is impossible. My book Breaking the Free Will Illusion for the Betterment of Humankind goes into the details of why both of these ways that events can come about are absolutely incompatible with free will. I also explain why these are the only two possibilities for events, and get into some of the problems that acausality needs to contend with. I’ll also be writing more articles on causality and acausality, so please subscribe to keep up to date. In the meantime, here’s some help in understanding causality a little better: Otherwise a Causal Contradiction
For this article, I’d like people to understand that free will being logically impossible is not tied to any notions that we can predict the future. When someone tells you “but we cannot know or predict the future” when defending free will (even if they are a well-respected authority figure such as Michio Kaku), you can stop them in their tracks right then and there. Such is irrelevant to our understandings of why free will is impossible. Make it clear to them that the main arguments against free will don’t require a possibility of future predictive powers.