Causa sui is the Latin name for a self-caused cause, one that is not the result of prior events.
A main idea in modern quantum mechanical indeterminism is an event that is unpredictable from prior events, or at best can be predicted only with some probability, not certainty. Can we regard that as a causa sui? We will see that a quantum event can play a similar role to the causa sui of the ancients, initiating a new causal chain of events in the macroscopic world.
Causa sui in theology is associated with the power of God to perform miracles, which are often thought to cause major changes in the physical world. In contrast, our quantum-mechanical causa sui will be seen to be almost the least amount of change in the physical world that one might imagine. Nevertheless, in the right places quantum events can be a difference that makes all the difference.
A quantum mechanical event is initially only one atomic (or subatomic) particle that is here rather than there, or events that do or do not occur - unpredictably. This unpredictability has been exaggerated beyond reason by some philosophers who claim extravagant possibilities, like fish turning to stone (P. H. Nowell-Smith). To appreciate how small the typical quantum event is, think of it as one particle in the 1024 atoms that make up human-size objects.
So our quantum-mechanical causa sui is quite minor, yet it can have a major effect - if it is part of a thought. For it is in immaterial thoughts (pure information) that simple presence or absence can be a most meaningful difference, for example the negation of a thought (or action dependent on that thought). Our causa sui can be the difference between being and nothingness, between one and zero, between yes and no, something rather than nothing.
The core idea of determinism is closely related to the idea of causality. But we can have causality without determinism, if among the causes is a quantum event that was itself unpredictable and to some extent uncaused. And the departure from strict causality is very slight compared to the miraculous ideas associated with the causa sui of the ancients.
We call it "soft causality".
Despite David Hume's critical attack on the necessity of causes, many philosophers embrace causality strongly. Some even connect it to the very possibility of logic and reason.
Generally they oppose the idea of a "dreaded causa sui."
Even in a world that contains quantum uncertainty, macroscopic objects are determined to an extraordinary degree. Newton's laws of motion are deterministic enough to send men to the moon and back.
In our Cogito model, the Macro Mind is large enough to ignore quantum uncertainty for the purpose of the reasoning will. The neural system is robust enough to insure that mental decisions are reliably transmitted to our limbs.
We call this determinism, limited as it is in extremely small structures, "adequate determinism." The world is adequately determined to send men to the moon. The presence of quantum uncertainty leads philosophers to call the world "indeterministic."
They logically and simplistically argue that if determinism is not true, then indeterminism must be true. But indeterminism is seriously misleading when most events in the world are overwhelmingly "adequately determined."
Adequate determinism means that we can usually understand the causes for events, despite the fact that some causes for our actions are surprising, even to us, and after the fact seem to have been unpredictable, the result of a causa sui.
There is no problem imagining that the three traditional mental faculties of reason - perception, conception, and comprehension - are all carried on deterministically in a physical brain where quantum events do not interfere with normal operations.
There is also no problem imagining a role for randomness in the brain in the form of quantum level noise. Noise can introduce random errors into stored memories. Noise could create random associations of ideas during memory recall. This randomness may be driven by microscopic fluctuations that are amplified to the macroscopic level. Such randomness is at the heart of the idea of a causa sui.
Our Macro Mind needs the Micro Mind for the free action items and thoughts in an Agenda of alternative possibilities to be de-liberated by the will. The random Micro Mind is the "free" in free will and the source of human creativity. The adequately determined Macro Mind is the "will" in free will that de-liberates, choosing actions for which we can be morally responsible.