“Free will” is an ethical concept, not physics

Academic philosophers (or the physicists who like to chime in) like to debate whether we have free will, because our brains are physical things, subject to the laws of physics. A fun puzzle, but there is a deeper, more important question to answer.
Free will is not just a philosophical puzzle, it is an important real-life issue, with serious consequences. We base decisions on whether to reward or punish people, depending on whether or not their actions were performed of their own free will.
The everyday issue of free will is a question as to when we should hold people accountable or relieve people of accountability for their actions; it has a real impact, possibly leading to people being punished or rewarded.
If someone says “I can’t do that today, I don’t have enough energy”, we don’t invoke E=MC2 and explain that with their body mass, they have plenty of energy. At least in the energy case, there is a rigorous scientific analog of the everyday concept. If free will doesn’t work for physics, fine, but philosophy does need to help with the everyday concept, so let’s see how that works instead.
We answer the question of whether a person acted of their own free will by asking whether they may have been compelled to act by external forces or if their brain was acting abnormally (for example, because of a tumour or a more subtle mental illness).
We do this because some of our current theories on how to change the behaviour of people for the better suggest that we can change the states of their brains in such a way that more desired outcomes will be achieved. One way we do that is through systems of reward and punishment, that we expect will either change the behaviour of the person in question or, by example, deter or encourage others.
We know this is futile if the more subtle changes in brains brought about by reward and punishment will be overwhelmed by more obvious brain damage or physical force. So we don’t fine people, throw them in jail or express moral disapproval, if their action was compelled.
It is time we focused more on this aspect of free will than on spurious questions about whether, given the initial state of the universe and the laws of physics, the actions of a person are pre-determined. It is equally irrelevant to know whether there are macro-level effects of quantum indeterminacy on human actions.
What does matter is to find out how our current laws and attitudes can be improved and, if so, should we update the short-hand phrase “free will” to better fit those improvements.
For example, the current number of people with mental illness who are being “treated” by our justice system is a scandal. Many of the people directly involved, such as judges, police, probation officers and jailers, realize that people with mental health problems who commit crimes are not well-served by the justice system, nor does criminalizing the mentally ill reduce any harm done to the public.
Of course,the majority of mentally ill people do not commit crimes, but many of them are punished for their “deviance” by means of more subtle social tools of disapprobation, from frowns to exclusion.
People with addictions have a lower measure of free will than if they did not, which is to say they are more constrained and more likely to do things they would otherwise not. So free will is not “all or nothing”; there are degrees of free will. This applies to being possessed of some ideology as well.
I suggest that philosophers should join the rest of us and spend more of their time investigating the whole complex of ideas involved in our ability to make decisions, including “free will” as a network of related concepts.