Simple uncertainty is the absence of certainty. Certainty was a postulate from the earliest times in such fields as logic, mathematics, and physics. In the late nineteenth century, the work of Frege and others cast doubts on logical certainty. In the nineteen-thirties, Gödel called mathematical certainty into question for all but the simplest systems of arithmetic.
Physical uncertainty today is the consequence of Werner Heisenberg's Uncertainty Principle in quantum mechanics. It states that the exact position and momentum of an atomic particle can only be known within certain (sic) limits. The product of the position error and the momentum error is greater than or equal to Planck's constant h.
ΔpΔx ≥ h/2πThe Indeterminacy (Unbestimmtheit) Principle was Heisenberg's original name for his principle. It is a better name than the more popular uncertainty, which connotes lack of knowledge. The Heisenberg principle is an ontological as well as epistemic lack of information.
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. Our Cogito model of 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.
Although it is limited by indeterminacy in extremely small structures, we call this determinism "adequate determinism." The world is adequately determined to send men to the moon. Some philosophers deny quantum uncertainty because it implies that the world is undetermined. But indeterminism is seriously misleading when most events are overwhelmingly "adequately determined."
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 uncertainty 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 uncertainty may be driven by microscopic fluctuations that are amplified to the macroscopic level.
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 uncertain 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.