It seems evident to me that free will is an illusion. I will not argue for this view here, but I will address one common concern. Usually when arguing for determinism, people counter that the justice system will fall apart. Ignoring the fact that the consequences of believing in determinism are irrelevant to the empirical question of free will’s existence, I don’t think a deterministic worldview necessarily invalidates justice.
The modern American justice system is retributive; it punishes people because they have done something wrong. This works because people are assumed to have free will, and so they are responsible for their actions. Even if punishing criminals would lead to negative social benefits (e.g. tax spending), many in society would still advocate it. Simply put, we get an intuitive pleasure from revenge against those we believe intentionally did evil. Of course, there are much more practical arguments, such as deterrence. The fear here is that if we don’t punish people with retribution, then future criminals will not be deterred. This argument is on somewhat loose empirical footing. From the literature on ego-depletion, people commit crimes when their willpower is exhausted from doing other daily tasks (willpower being a limited cognitive resource). This is why the poor are more likely to commit crimes – they face more daily stress, and so their willpower is depleted much quicker. As such, even if the costs of a crime are high, criminals may not be able to “rationally” carry-out a cost-benefit analysis. This is not to say that there is no deterrence effect from punishment, but that it is often exaggerated. To be fair, the academic literature does not reveal a consensus. In fact, beliefs about crime deterrence seem to be based on ideology. For example, arguments on the deterrence effect of capital punishment are somewhat occupation-based, in which economists are the only social scientists who tend to find a deterrence effect.
I advocate the sociological understanding of crime. Criminals are not malicious, but are instead driven to their actions by environmental factors. I do not reject the deterrence effect of punishment completely though (it would be absurd to), and so I recognize that it is problematic to absolve criminals of all agency. Indeed, if we punished no one, I agree crime will increase. Yet, we must still pay attention to the injustice of criminal punishment; if free will doesn’t exist, then how is it fair to punish people who did not choose to commit crimes? They may not have free will, but they still feel suffering. The solution is to embed a moral purpose into the justice system other than revenge.
I believe the best way to do this is to treat criminals as if they are sick. Take someone with a deadly contagious disease. The sick man runs the risk of infecting people, but we recognize this is not his fault. As such, instead of killing him (surely the easiest response), we quarantine and treat him until he gets better. We don’t condemn him. The justice system can work in a similar way. Once we recognize that criminals are not at fault for their actions, we can try to help them instead of punish them. For example, if someone is a mugger, we can isolate him in a prison so that he does not mug more people. However, rather than just holding him there, we can change his social standing so that he has better alternatives to crime. We could train him in a professional skill for example, so that he can get a job and not resort to mugging. For crimes like rape or murder, we can provide psychological counseling to curb their behavior, so that later they can reintegrate into society without any urges to rape or murder. I realize this may seem absurd – “how can we just let rapists free?!?” – but once we accept a deterministic worldview, the alternative in which we punish people for things they did not freely will to do seems even more absurd.
Philosophically, the restorative justice system is the moral choice. It gives people the chance to redeem themselves and live a dignified life, where actions beyond their control do not follow them. Practically, it will lead to greater social benefits by creating more socially-beneficial members of society. As the saying goes, prison is a place where criminals learn to become better criminals. Consider the positions criminals are in: they get out of prison, and no one will hire them. What else can they do to survive except turn back to crime? If we instead remove the stigma of prisoners, and help them reintegrate into society, then their recidivism rate will go down. A version of this system already exists in some places around the world. In Norway for example, criminals are taught new skills and there is no lifetime imprisonment; Andres Breivik, the Norwegian mass murderer who killed 77 people at a youth camp, was only given a 21 year sentence. Of course, his sentence can be extended if he is not deemed to have been rehabilitated, but it sends a message that the Norwegian system accepts that all humans can be redeemed. This echoes the medical-styled system I am advocating; just as a sick man is only quarantined until he gets better, criminals should only be imprisoned until they are “better.” We should not be so quick to condemn people for actions beyond their control, and we should always allow people to be redeemed. Remember the words of Foucault: “There is no glory in punishing.”
The Revisionists 
Determinism and Responsibility
Determinism is nothing more than the belief in cause and effect. Every change, every event, every action, every phenomenon in the real world can, at least in theory, be accounted for in terms of one or more specific causes that made it happen. And each of these specific causes is itself a change, event, action, or phenomena in the real world, with its own specific causes. These chains of causes reach back to the beginning of time and will reach forward to its end.
Everything that happens is, in theory, inevitable. This was never a big deal until some dumb philosopher suggested that, if everything is inevitable, then (1) everything is beyond our control, and, (2) we cannot be held responsible for anything we do.
Both assumptions are false.
The first assumption is false because, although many things are beyond our control, we are actually the relevant causes of a great deal of what happens in this world. And these events are only inevitable because of choices we deliberately made.
Are our choices also inevitable? Of course. When we make a deliberate choice, we consider alternatives, we estimate the outcomes of one option over another, and then we choose what we think or feel would be best. Given sufficient knowledge of the decider and the situation, even the amateur could predict the outcome with reasonable reliability. But the decider himself will not know for sure until he has actually made the decision. Knowledge that the decision is theoretically inevitable and predictable is completely useless to the decider.
The second assumption is false because it misrepresents the meaning of “holding responsible”. In all practical matters, to “hold” someone or something “responsible” actually means to identify who or what needs to be corrected.
Suppose a person decides that he can “hold his liquor” and drive safely home after a party. He may do this successfully many times. But then his inebriation causes him to lose attention and hit a pedestrian crossing the street.
His conscious decision to drink and drive caused a fatal accident. And it also was the relevant cause of his arrest, conviction, and punishment.
He cannot claim exemption from punishment due to the “inevitability” of his choice to drink and drive. There is nothing we can do to rewrite the offender’s personal history. The practical problem at this point is how we might influence his future behavior. Therefore, the person as he is now is the “point of correction” rather than his past, and it is the person as he is now that is “held responsible” for the pedestrian’s death.
So, determinism does nothing to release anyone from being held responsible for their choices. We may, though, by studying those early influences, design educational programs to reduce the likelihood that others will make the same bad choice.
There is nothing in determinism that diminishes personal responsibility or the impact of the decisions we make of our own free will. And free will itself exists quite comfortably within the context of a deterministic universe.