One thing is very clear...it is even more difficult to define free will than it will ever be to measure free will and so it is important to first define free will in order to ever hope to measure free will. If it is not clear exactly how we make free choices versus determinate choices in the first place, measuring free choice would then be undefined as well.
However, if there were a determinate measure of free will precursors to a choice like a scalar zeta, it is clear that that would not then be free choice since a predictable choice cannot be a free choice. There are only two ways out of the determinate conundrum of individual freedom versus social responsibility; the noise of classical chaos and noise of quantum phase. In particular, a free choice is one that we make based on gut feeling and so there may be any number of constraints on that free choice. Feelings derive from emotions and how exactly we feel about a choice can be impossible to truly know.
There are many things that we cannot ever truly know and neither the noise of classical chaos nor the noise of quantum phase have completely knowable precursors even though those precursors do exist for each in the causal universe. Unknowable precursors represent the mystery of free choice and being and feeling and are things that we must simply accept. The universe is after all just the way that it is first of all. The precursors of free choice must be unknowable since free choice represents the balance between individual freedom and social responsibility and we achieve that balance with our feelings and not by reasoning. The noise of classical chaos, Shannon noise, is what we call random action but the noise of classical chaos is actually not really random at all. In fact, classical chaos is in principle infinitely resolvable and therefore knowable with infinitely resolvable space and time. Therefore classical random noise is actually just a recognition of a practical limit of the knowable precursors precursors of random noise. However, the noise of a quantum superposition outcome has a well-defined discrete limit and yet will still not have completely knowable precursors even though quantum choices can be very likely.
While classical choices all have knowable precursors, quantum choices do not since they are superpositions of precursors and outcomes and do not have infinitely resolvable precursors. The decay of quantum phase results in a real outcome and so even a real outcome does not have any precisely knowable precursors, just more likely precursors. Quantum phase decay is a consequence of the very slow intrinsic change in the universe. Quantum outcomes do have more likely precursors and our individual freedom and social responsibility mean that we cannot know the precursors of free choice with infinitely resolvable precision even though those precursors do exist in a causal universe.
In other words, while we believe might that we are free and socially responsible, we cannot ever be completely certain about individual freedom or about social responsibility, we just have feelings about them. This means that there is a discrete quantum limit to the knowledge that we may have about our individual freedom and so there are fundamental mysteries about the universe that we must simply accept as the way that the universe is.
Thus, individual freedom exists in a balance with social responsibility as the fundamental duality of the mystery of free choice. Random choices are unpredictable just like free choices are unpredictable and so Durham argues along with many others that random choices are not free choices. Likewise, choices by instinct, Durham further argues, are also not free choices and so the classical reasoning of chaos imposes its infinitesimals and infinities upon our discrete causal quantum universe. Random action is just a convenient shortcut for the practical limit for knowledge of precursors and it is always ironic that in a causal universe things can ever happen for unknowable causes.
What classical physics really means by random is not that random things are fundamentally unknowable, but rather that random things are just practically unknowable. Classically, there is no limit to resolving uncertainty except just a practical limit since all action has infinitely divisible momentum along with infinitely divisible displacement. Thus random simply represents the practical limit to knowing the classical precursors of classical outcomes.
In fact, there is a classical practical limit to knowing Shannon noise, but that does not then mean that noise is truly random. In fact, computer algorithms simulate random noise to arbitrary precision quite well with determinate algorithms. Therefore, the universe really is not fundamentally random as Durham claims, but more like effectively random just like the determinate computer algorithms of noise are not fundamentally random. Classical Shannon noise is then what we call random but in a classical causal universe, each bit of Shannon noise does actually have knowable precursors in an infinity of divisibility.
Quantum phase noise is really very similar to classical Shannon noise, but quantum phase noise includes quantum phase and the phase decay of the universe. Quantum phase decay is the fundamental driver in the discrete causal universe and quantum phase decay is therefore not really random in the classical sense. Quantum phase noise is random in the quantum sense of superposition and correlation and the likelihood of Schumacher's qubits and von Neumann's density matrices. Unlike the unlimited divisibility and knowledge of Shannon's bits, qubits represent the discrete limit of knowledge in the quantum universe.
Free choice is of course an essential part of our nature and we have a free choice between the selfishness of individual freedom and the compassion of social responsibility. The most direct free choice is how we freely choose to act like other people and then how they freely choose to act like we act. When we agree with other people about a conscious state, our subjective feeling becomes an shared objective feeling, but even very smart people like Durham can still disagree about the natures of free choice and free will as well as individual freedom versus social responsibility.
Even more objective measures of free choice are in the resonances of neural action potentials as EEG spectra. Although EEG resonances are objective measures of the conscious state, EEG’s do not necessarily measure the quality of any conscious state...at least not with present technology. In fact, every neural action potential network, even those of a mouse or even a house fly or indeed a pond hydra, show the resonances of some kind of limited neural free choice. However, fundamental particles do not show neural resonances and therefore are not conscious. Measuring both waking and sleeping state EEG's of neural networks provides objective measures of awake conscious spectra versus the unconscious spectra of sleep as resonance frequencies and resonance widths.
The EEG spectrum delta mode is a fundamental resonance of human neural action potentials at 1.5 Hz with a full width of 1.5 Hz. The fundamental modes of free choice are the overtone alpha modes at 11 Hz = 7x delta and beta modes at 21 Hz = 14x delta and represent the human conscious state, all with similar widths. These multiples are not accidents of nature but rather are a consequence of the neural structures of the hexagonal close-packing of the eye's retina and the sound octaves of the ear's cochlea. Thus humans have many of the same neural resonances as other sentient neural action potentials.