Positing the existence of free will (the ability to choose between available options) is merely a way of accounting for facts that otherwise cannot be accounted for. Such as this:
All quite accountable to causality.
What do you mean? "Causality" is "the relation of cause and effect".
the definition of causality
No one here has denied the relation between cause and effect.
The ability to choose among available options is not accounted for as the effect of any known "physical" phenomenon, nor accounted for by any law of nature. If humans lack the ability to choose to perform or not perform our acts, then all of our acts are involuntary bodily movements like muscle cramps or heart attacks. Humans cannot predict their involuntary muscle movements a day in advance. Yet I said in an earlier post that I would write a post the next day containing the name of King Lear's youngest daughter. And I did exactly that. Making such an announcement then writing a post with "Cordelia" in it is not accounted for as an involuntary bodily movement. It was a voluntary bodily movement.
The responses of the nervous system to stimuli may be voluntary or involuntary. Voluntary responses are mainly under conscious control, but some voluntary movements, such as walking, require less conscious attention. There are two types of involuntary response, autonomic and reflex. Autonomic responses regulate the body’s internal environment. Reflexes mainly affect those muscles that are normally under voluntary control.
Voluntary responses
All voluntary activities involve the brain, which sends out the motor impulses that control movement. These motor signals are initiated by thought and most also involve a response to sensory stimuli. For example, people use sight and sense of position to help them coordinate the action of walking.
Medical Encyclopedia - Function: Voluntary and Involuntary Responses - Aviva
This distinction between voluntary and involuntary bodily movements is the basis of diagnoses of dyskinesia.