The indeterminacy of QM offers nothing in explaining the contradictory nature of free will. Free will asserts both something occurring outside the causal chain as well as the agent's control, and therefore responsibility, over that event, which is to suggest a God-like property that defies explanation. — Hanover
I think this is a problem that afflict some libertarian (so-called) 'contra-causal' conceptions of free will. According to such conceptions, while most natural events are governed by universal laws, acts of the will interfere with the working of those laws such that, in the case where an agent did something, if the history of the universe were to be rolled-back to its initial state before the person acted, then, in those exact same 'circumstances', the possibility that she could have done otherwise remains open; and the counterfactual actualization of this possibility also is being construed as the manifestation of an act of the agent's will. (This is one possible construal of the
principle of alternative possibilities, of PAP).
The main trouble with this conception relates to what Robert Kane has called 'the problem of intelligibility'. If in the exact same 'circumstances' where an agent might equally give expression to the state of her will though doing A or doing B, where A and B are two incompatible actions that satisfy incompatible rationales, then how do we account for such acts of the will that are thereby insensitive to reasons that may favor A over B (or vice versa)? We would have to imagine that the 'state the will' of the agent -- which presumably includes some degree of awareness of, or sensitivity to, the reasons that the agent has for acting -- resides outside of the 'circumstances' of the agent, where those 'circumstances' are construed by the contra-causal libertarian as to includes the agent's whole history down to the exact neurophysiological state of her brain.
On my view, compatibilists are right to object to such a thin (and likely incoherent) conception of the agent and of her will such that they are not only free from the constraints that natural laws put on material processes but such that they can also act
against them. Compatibilists rather (and more plausibly) seek to account for the features of the will in such a manner that, while it isn't so much as partially free from natural constraints, many of those 'constraints' aren't best construed as constrains
on the agent's freedom but rather as rational or motivational constraints
that the agent herself exerts on her own actions. She doesn't exercise them from outside of her 'circumstances', as the contra-causal libertarian would have it, but rather while still being subjected to the 'internal' circumstances that are partially constitutive of who she is as an embodied rational agent. Such 'internal circumstances' include some features of her history that have led to her acquiring practical rational deliberative abilities and some contingent set of motivations.
So, when QM is being construed as providing some leeway into the broadly deterministic laws of nature, such that if the 'state of the universe' (or the 'state' of an embodied agent and of her 'circumstances') were to be rolled-back to some fixed earlier state, then, in that case, the agent might have acted differently, no satisfactory account is thereby provided of the freedom
of the agent. And that's because of the aforementioned 'problem of intelligibility'.
On the other hand, another feature of QM could have some relevance -- analogical rather than explanatory -- to the problem of free-will and determinism. And this feature has very little to do with the fundamental indeterminacy of the potential outcomes of measurement processes effected on quantum mechanical 'systems'. It rather has to do with the radical
inseparability of the physical phenomena from the embodied and situated context within which those phenomena are being teased out from a determinate experimental set-up. It is because of this fundamental inseparability that it makes no sense to inquire about the actual position of an electron in the circumstances where the experimental set up has been established so as to measure its momentum. On that view, the very idea of the position of an electron (which is called an 'observable' in QM) is essentially relational rather than being a characterization of the intrinsic state of an individual electron. The position of an electron characterizes possible interactions of the electron with an observer which are only possible in a range of set-ups that are inconsistent with the observation of its (precise) momentum, and
vice versa. So, attempts to characterize the electron's behavior deterministically, such that prior to having been observed it would already be disposed to manifest determinate positions and momenta, are attempts to separate the phenomenon from the circumstances of its
constitution. This can't be achieved according to Bohr's or Heisenberg's interpretation of QM. On my view, hidden-variable or many-worlds interpretations of QM can be construed as attempts to rescue the metaphysical view from nowhere of physical reality such that quantum phenomena can be given non-relational descriptions that, however weird, still comport somewhat with our intuitions of the classical-mechanical universe: an universe that is populated with items that have the kinds of determinations that they have quite independently from the nature of our interactions with them. Both of those classes of interpretations seek to dispense with the essentially relational nature of quantum phenomena. They reflect attempts by the theorist to radically separate herself from the universe which she seeks to describe and explain from a point of view that abstracts (
per impossibile) from her constitutive relations with the phenomena that she observes.
I'd like to propose that both contra-causal libertarian accounts of free-will
and most compatibilist accounts of free-will suffer from a defect that is deeply analogical to the 'metaphysical' (or 'realist') interpretations of QM. In the case of free-will accounts, though, the impossible task that is being attempted is the task of separating the
agent from her world rather than the task of separating the observer/theorist from her world. Most compatibilist philosophers, on my view, only recognize partially the essentially relational character of agency since, unlike contra-causal libertarians, they acknowledge that parts of the 'circumstances' of an agent really are constitutive of who she is, as a radically embodied agent, rather than representing constraints on her agency which only operate 'from without'. On the other hand, they tend to theorize this separation between internal 'circumstances' (e.g. desires, values, reason) and external circumstances (knowledge, coercitions, physical limitations) from a point of view that is
still a view from nowhere, and hence that allows from a deterministic psychology of the 'internal circumstances' of an agent. Because of that, I think, most compatibilists miss out on the nature of rational-causation, and of the autonomy of practical reason, as a neo-Kantian might conceive of them in irreducibly relational terms.