Developing systems of morality, outside of religious influence.

[Angrboda]

Doesn't this entire conversation presuppose free will? But I know some of you don't believe in free will. How does a determinist justify a belief in moral values and duties?

No, it does not. Morals and internal governance via morals is all about shaping behavior for the benefit of the society of which an individual is a part. Even without free will, we would still desire the benefits to be gained from shaping individual behavior in ways that are conducive to the well being of the individual, the society, our species, and ultimately our planet. I don't see how eliminating free will renders any of these goals any less desirable. An interest in such common goals is justified by the principle that a rising tide lifts all boats, and it avoids such dangers as a behavioral tragedy of the commons. It's not hard at all to justify morals in a deterministic worldview.

Moreover, the question of morals, free will, and punishment often come up together from free will advocates who suggest that we have no basis for punishment of immoral/illegal acts if we don't have free will. I feel this view is mistaken. I have opined upon the subject before, so I'll simply paste my thoughts from a previous discussion.

I've made the argument before, but to my mind, punishment serves one of 5 possible goals: (I just added one)

1. Insuring the safety of innocents by isolating offenders from the community and depriving them of the opportunity to re-offend;
2. Deterrence;
3. Rehabilitation;
4. Compensation - the redistributing of the fruits of the offender's resources to compensate society;
5. Retribution - making someone "pay" for what they have done because they are morally deserving of punishment.

As noted, deterrence is generally not regarded as effective. And retribution is probably, from a moral and practical standpoint, one of the least compelling justifications for punishment. I'm not going to elaborate further where this suggests we head with criminal punishment except to point out two key points.

In Michel Foucault's landmark study of the history of punishment, Discipline and Punish, he points out how, with the reforms in punishment that have occurred in Europe since the 16th century, the focus of punishment has shifted away from punishing the individual for an act to one in which we largely punish and attempt to correct the person as someone who has a mind capable of committing such acts. Thus we allow insanity as a defense, because the person's inclination to commit crime is not amenable to the treatment, punishment. We adjust the punishment dependent on the goal of fixing the criminality of the mind, not on addressing the severity of the crime; three strikes and you're out is aimed at minds that can't be fixed, not crimes that have been committed. Child molesters can be given chemical or surgical castration in exchange for reduction of sentence and leniency. Prisoners are monitored for progress and paroled earlier if they "show signs of good character" — it's not the crime that determines punishment anymore, it's the predisposition to offend which is the focus of punishment. Retribution, perhaps, is a return to focus on the crime rather than on fixing the criminal mind, but I'd be hesitant to take that step without serious consideration as to whether doing so serves any legitimate purpose.

The second point is, that as a hard determinist, I don't believe in free will. The moral justification for using punishment as retribution for a crime is that the person is morally deserving of the punishment, and that requires moral culpability which doesn't exist in the required sense if free will doesn't exist. The other four aims of punishment — deterrence, isolation from society, compensation, and rehabilitation — all can be justified without recourse to the assumption of free will; retribution alone cannot. Now I recognize that relative to my peers, I hold an extreme view with regard to free will, yet I think many of us realize that, regardless of where on the continuum regarding the existence of free will you stand, most of us recognize that most crimes and criminal behavior is a consequence of both factors within the individual's control, as well as a large measure of factors totally outside their control, ranging from social class, education, intelligence, all the way to things like being born in a society or culture that encouraged certain values and not others, to being genetically fated to the development of temperament which leaves one at increased risk of criminal or violent behavior. As a personal matter, I try to remove free will from any justification for punishment; but even someone more moderate could well be persuaded to minimize the impact that situational factors such as being born black, being poor, and such have on the fairness and equity with which we address criminal behavior; I think, arguably, retribution results in unfairness because it treats moral culpability and the resources to act morally as evenly distributed resources, and they are not.