Q: Isn't this an ancient philosophical question, an idle question?
A: Resolution of the nature of Free Will is is not an idle philosophical question, it is one of the greatest challenges facing western civilization, impacting law, education, child rearing, psychiatry, medicine and the daily lives of individuals. How this is resolved will have immense impact.
A: An important if not essential factor in a person's capacity to control a behavior is belief that one has the capacity to control the behavior. The single greatest predictor of success in many situations is ones sense of self-efficacy. Nothing reduces motivation like the message that the task is hopeless.
A: Minimization of human agency contributes to the following trends:
The use of drugs to influence behaviors as diverse as weight control, mood, anxiety, children's compliance with adult commands and paying attention in class. Soon neurological techniques such as magnetic stimulation of neural pathways will compete with medication.
On the other hand, blame and punishment for behavior outside the control of the individual has produced untold suffering. The trick, as always, is knowing what can be controlled and what can't.
A: Depends who is writing the history. Darwin's theory of evolution was initially deemed impossible by mainstream physicists. The argument was that the earth could not be as old as Darwin's theory required because the sun's supply of flammable gas was not that vast. The evidence of geology in support of a very ancient earth was rejected for the same reason. Physics was wrong. Biology and geology were right. The error of physics was that an entirely new phenomena was unknown. This would be corrected with the discovery of nuclear energy. Only then was physics reconciled with an earth over 100,000 years old.
My history of science sees no reason to give physics hegemony over the other sciences.
A: If every cause is determined by a prior cause, then Free Will appears unlikely. If some acts are random, this transfers causation from prior causes to random events - again making Free Will appear unlikely. However, both examples are based on an assumption of classical physics that everything has a cause. The core issue is whether everything has a physical cause.
Q: Is acausality a possibility?
With quantum physics we fall down a rabbit hole. Phenomena such as entanglement bring all assumptions into question. Einstein called entanglement "Spooky action at a distance." Two subatomic particles appear to influence each other at a distance instantaneously. Then there are small issues such as dual nature - a photon being both a (wave and a particle, or a photon going two difference paths simultaneously. Not to mention observation changing reality. How about time travel. Physics is simply too undeveloped to claim authority to rule in conditions ruling out Free will.