The common tacit understanding of free will, when made explicit, as formally known as libertarian free will, is that it is contra-causal - above and beyond any natural processes (typically captured by the idea of a combination of genes and environment) - with some form of supernatural aspect, we could call it a supernatural or spiritual dimension. Now whether one refers to the "Self", "Soul" or "Spirit" etc. does this permit the freedom needed for responsibility, beyond the determinisms of genes and environment or both?
Supporters of libertarian free will assume that determinism is incompatible with free will, that it is either one or the other. They further assume that without free will there is no responsibility and so, presumably, there is no basis, say, for punishing people for crimes. Does this presumption make sense, or could it be otherwise, that far from being “free”, this merely adds third type of determinism alongside environmental and genetic?
Lets create a deliberate caricature of this, made to look like defences relying on the libertarian free will characterisation that determinism shows the moral emptiness of an agent incapable of responsibility for their actions:
Imagine three guilty defendants pleading mitigating circumstances in court, presumably on the basis of hoping to receive a reduced sentence from the judge:
Edward: “It was not my fault m'lurd, it was the result of growing up in a council flat, with a dysfunctional family and a broken home”
Gerard: “It was not me fault, m'lurd, you see I have inherited aggressive genes”
Simon: “It was not my fault, m'lurd, I was following the dictates of my soul and that trumps anything else”
Now how is the judge to decide on sentencing? Well in all three case nothing gives a justification to shorten the sentence as they all imply a current incapability to respond within the laws of the land. However rehabilitation is possible for Edward and Gerard - they might respond to this. Edward could obtain new environmental conditioning to overcame his history. Similarly Gerard could also possibly respond to learn to better control his genetic impulses - genes and environment are not islands they interact. What hope is there for Simon? Rehabilitation would not work, if his soul decides otherwise that is that, it is beyond reach of rehabilitation.
Edward and Gerard have a chance because they can, in spite of the presumption behind libertarian free will, be held responsible for their current and future actions, since they are potentially sensitive to the causal factors that affect everyone. Simon clearly is not (unless one allows for rehabilitation of Simon from the delusion that his soul can make him immune or over-ride the causal factors - but that is a separate topic on the freedom of belief issue). How ironical that a fear that those who support libertarian free will trade off is more likely made true if there really is libertarian free will!
Built in behind this above caricature is the presumption the determinism simpliciter prevents any freedom required for responsibility but we have already seen the opposite. However the above is meant to show that a brute and misleading characterisation of determinism presumed by some supporters of libertarian free will, can not only apply to their own solution but can only apply to their own solution.
This is not not meant to be a complete knock down argument showing that libertarian free will is self-defeating but it is indicative of the absurdities behind the presumptions of libertarian free will.