The words “determinism” and “indeterminism” tend to cause a lots o’ confusion when they are used. That’s because, as with many words/terms, they can often be used with ambiguous meanings. This post is going to point to some of these usages and also to the common usage that’s of importance for the debate on free will.
Let’s start with determinism and look at the possible ways this has been used by others.
For many such as myself, determinism is interlinked entirely with causality. It says something about the universe and all events that ever happen within it. If every event that happens in the universe has a cause, the universe, per this definition, is said to be “deterministic”.
This correlates to how such word is used in physics. If every event has a variable that can account for the event taking place, such would be considered a “deterministic” model of physics. Newtonian physics was said to be such a model. When quantum physics (the physics of the very teenie tiny micro scale) came about, a wrench was thrown into the Newtonian model.
Due to Bell’s theorem (also known as Bell’s inequality), it’s been accepted by most physicists that the local account of causality implied by Newtonian mechanics did not work for some quantum events. For them to work, such would need to exceed the speed of light, a speed limit that most physicists don’t think can be breached. Einstein didn’t like this.
This implied that either some of these quantum events don’t have a cause (are acausal) or if they do have a cause, such needs to be “non-local”. Non-locality is another one of those confusing terms, but it basically means “action at a distance”. Recent experimentation on entangled particles does show that we can have instantaneous action at a distance.
Due to the bizarre findings at the quantum scale, which entails experiments such as the “double-slit” experiment, theories on wave-particle duality and collapse, entanglement, Bell’s inequality, and so on, physicists often assessed and leaned toward one quantum interpretation over another. These “interpretations” tended to be more “philosophical” by nature, attempting to explain the strange results and mathematics of quantum mechanics in their own differing ways.
Some of these interpretations are considered “indeterministic” such as the Copenhagen interpretation (the most commonly taught interpretation). Others are considered “deterministic” such as Bohmian Mechanics (also known as pilot wave theory), which is a non-local hidden variable interpretation, or Many Worlds, which was an interpretation that suggests a split into many different “universes” for each event. And still others are more agnostic (not taking a position) on the “determinism/indeterminism” status such as the Ensemble interpretation. Rather than go into depth on each quantum interpretation, what’s important is what qualifies such to hold its deterministic or indeterministic status. And that seems to be whether or not all events have a cause (a variable), whether some do not, or if an interpretation doesn’t make a claim either way. If all events have a cause, the physics of the universe is said to be “deterministic”, if some do not, it’s said to be indeterministic. And of course if a claim is not made either way, such interpretation does not hold a position (it could be either).
Another usage of these terms, and one that people often confuse, is the idea that it’s about if “we” can “determine the outcome. If we can predict the outcome, such can be “determined” and some suggest this is what makes for determinism. If we cannot predict the outcome, such is said to be “indeterministic”. Some claim the uncertainty principle is indeterministic because we can’t measure both the momentum and position with accuracy at the same time. This, however, goes against the other definition in which a non-local hidden variable interpretations (as well other hidden variable or many world interpretations) is considered “deterministic” (by practically all physicists)…even though we still can’t predict such. Rather, whether the uncertainty principle is “indeterministic” or not depends on the underlying quantum interpretation being postulated for it. But if we accept this definition that indeterminism means we can’t determine something, then such hidden variable interpretations can’t be deterministic as long as we have uncertainty and unpredictability. For most physicists this is not the normal definition of determinism and indeterminism, and problematic.
Never-the-less it’s one that people often use, and one that even some physicists do conflate, let alone the layperson. It’s understandable as the word “determine”, if we don’t really know the context or definition being used, can seemingly be attached to “us determining an event” (meaning finding out about) as well as “causes determining an event” (meaning leading to an output of). It’s the latter, not the former, that’s the more appropriate usage.
The reason for this is because physics as well as the free will debate is about what “is” (ontology), rather than what we can “know” (epistemology), but the idea that we can’t determine something is about what we can or cannot know rather than what exists. This is similar to the confusion about “probabilism” in quantum mechanics that some people have – which mix what exists with what we can and cannot know (confuses ontology and epistemology).
Determinism can also be defined this way: the initial condition will lead to the only future outcome it can lead to. The mistake is thinking that such is exclusive from every event in the universe having a cause (the first way we defined it). If there are no non-caused events, if every event has a cause (whether local or non-local), such must inevitably lead to a very specific future state. It’s the assessment of causality and what it implies if every event has a cause that leads to the idea that the initial condition will lead to the only future outcome possible (an inevitable future). And there are logical reasons for this assessment that I go over thoroughly in the book Breaking the Free Will Illusion for the Betterment of Humankind.
But these two ways of thinking about determinism are not mutually exclusive.
Like determinism, the term “indeterminism” has the same types of problems. The usage I use (and think important for the free will debate as well as physics), is that if non-caused events (what I call acausal events in my book) can and do happen, then the universe they happen in is said to be “indeterministic”. It simply means that all events are not “determined” by causes. Of course I go into a lot of the problems that such an event would have (in my book), but whether they are problematic or not is neither here nor there.
The confusions come when someone uses a different semantic of indeterminism, again that “we” cannot determine an outcome. For example, if we can only assess a probability that an event will take place, such would be considered “indeterministic” for this definition, even if that outcome is causal. But again, this usage of the word indeterminism goes against the common physics usage, is a knowledge issue rather than an understanding about what exists, and also the one of least philosophical importance for the free will debate.
Whether we can predict the events or not are irrelevant to the determinism or indeterminism definitions needed for this topic. Such is also irrelevant to the terms in physics, in which chaos theory is unpredictable yet entirely deterministic (the initial conditions causally lead to the outcome), and the unpredictability of the uncertainty principle hinges on the quantum interpretation being postulated that can either be deterministic or indeterministic.
One can also partition these words, which can cause further confusion. For example, they can say that perhaps there is indeterminism on the quantum scale, but on the larger scale everything is deterministic. In other words, one can claim that what coalesces at the small scale, even if acausal, is irrelevant to the causality at the large scale which is entirely deterministic. In this way someone can use these terms but partition them to the different scales of the universe. Or they can partition them to certain systems. For example, one can take a box and say that if everything is causal inside that box, the box is a deterministic system, regardless if there are indeterministic events outside of the box. Or a temporal (time) partition can be made. For example, if everything is causal from Monday to Friday, determinism applies during those days even if on Saturday an acausal event occurs.
I’m sure there are other ways these words can be used as well. What’s important for the free will topic isn’t so much the words “determinism” or “indeterminism”, but rather the assessment of the only two ways events can come about: either they are caused, or they are not. I also go over why these are the only two ways in my book.
And once we assess both of these, we can recognize what they mean for free will. And it just so happens that they are incompatible with the ability to have, of one’s own accord, done otherwise. Or in present tense: The ability to choose between more than one viable option or action, in which that choice was up to the chooser. And that’s the free will idea that is of concern for so many other topics.
But keep in mind that if you use these words, that some may have different ideas surrounding their meanings. When that happens, that’s when terms need to be defined and clarified. Or better yet, drop the term and just talk about causal and acausal events.
Just know that when I use the term, I mean them using these definitions:
- Determinism: All events have a cause.
- Indeterminism: Some events do not have a cause.
That’s all that is required. And there is no middle ground here. There is no event that is neither caused nor uncaused, as these are in opposition. If one doesn’t apply, the other must. If one does apply, the other must not. And hopefully this article will get you to see why these are the definitions of importance, the ones that are more common in physics, the ones that address what “is” rather than what we can “know”, and hopefully get you to adopt them. But if not, just make sure you know what another is talking about when they use these terms before your criticize based on a different (and often irrelevant) definition. After all, it’s a huge waste of time when two people talk past each other because they are using different semantics that never get clarified. 😉