Ever roll a 6 sided die? Of course you have. What is the probability of you rolling a 3? A 1 in 6 chance of rolling a 3 (or any other single number on the die)…right?
But what does this mean exactly?
In a universe where every event has a cause or causes (in a “deterministic” universe), is the 1 in 6 chance something that really exists? The short answer is no. It’s more of a limitation regarding our knowledge of what will happen, rather than there being a “true” 1 in 6 chance. If we were to know every variable, from the way the dice is held, to the trajectory of how it is thrown, to the weight of the dice, to the atmospheric condition, to the gravitational conditions, to the distance from the ground, to the surface it lands on, and so on…we could theoretically know the exact number the dice would come up with. It would be a 1 in 1 probability…or a 100% chance that it would land on that number.
Because of this, probabilty is something that pertains to our for-knowledge (or in philosophical jargon – it’s epistemological) rather than what exists (or in philosophical jargon – what is ontological). It’s very easy to confuse “knowledge” claims with “existence” claims, and with probabilism this happens all of the time – particularly with the science of quantum mechanics (the science of the very tiny scale of particles/waves, sub-atomic particles, etc.)
Per various experiments such as what is known as the double split experiment, the nature of particles/waves is probabilistic. Think about the words “is probabilistic”. Sounds like probabilism is embedded within the nature of those particles. That the probabilism “exists“. This, however, is a big mistake.
In the book “Breaking the Free Will Illusion for the Betterment of Humankind” I dedicate a section on explaining why this idea of probabilism existing is wrong, even at the quantum scale. Rather, it’s always a position about what we can and cannot know.
If you know the topic a little, you might be thinking “but what about in a universe where some events don’t have a cause (an indeterministic universe)? For such events we could never assign a probability of them other than “at some time or never”. They would either happen at some unknown time, in some unknown location, …or never (or in philosophical jargon – they would have no temporal or spacial determinacy). In the book I go into depth explaining why this is problematic even for knowledge notions of probabilism.
And when it comes to the free will debate, some people have a tendency to suggest that the probabilistic nature of particles at the quantum scale sort of breaks the type of causality that is incompatible with free will. It doesn’t. Probabilism isn’t some third option between causal events and acausal events. Events are about what “exists” or what “will exist”. Probabilism is about “what we can know about events that will exist”.