Knock knock.
Who's there?
Nobody. Self is an illusory epiphenomenon emerging from the binding in time of separate neuronal populations via loops of neurons from cortical representations (sensation, motor action planning, etc) to the brain's switching center, the thalamus, and back operating at 40 times per second. This is necessary if not sufficient for what an average observer would call being conscious.
The epiphenomenon of consciousness is a prediction engine and it runs on entirely deterministic, entirely classically predictable hardware. No quantum woo-woo is needed or likely given the dense wet environment. The decoherence timescale for a plausible small molecule is 10 orders of magnitude shorter than the timescale of neuronal and astrocyte activity.
Free will is a relative quantity expressed in terms of the ratio of computational power available for each actor. We can have free will relative to something or some system but there's no absolute meaning of free will. Animals as we know them with nervous systems are predictable objects just like anything else.
I'm not saying it makes sense from the perspective of introspection. It seems absurd and obviously false.
I'm saying that's what the scientific evidence indicates it. One argument against it is that well before you are consciously aware of making a decision there are many neurological indicators (EEG P300 signals, fast near IR changes in scattering, and slow fMRI blood oxygenation, etc) that use the activity of sub-populations of neurons to correctly predict, for example, a motor behavior like choosing one of two buttons to press. This disconnect also exists in terms of conscious sensory perception of being pinched when external brain stimulation like rTMS can be used to inhibit perception. Or more dramatically when TMS is used in the pre-motor and motor cortices to initiate a preference for action, say, in a choice to twitch your right hand finger or your left. The brain confabulates an intention post-hoc to agree with the stimulation choice.
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