First off, you will need to decide what your worldview is or what your foundational beliefs are that form how you see the world. It would be best if you also knew how you formed that set of beliefs or what the ingredients are. Plato, in The Republic, tells the myth of Er in which Er returns from the dead, from hades, to inform the living about punishment in hades or rewards in the afterlife based on ‘just’ or ‘moral’ behavior in life. Plato had just witnessed the failure of Socrates’ ideology, that the philosopher would work with the State in a free and open dialogue to advance society. Indeed, the State murdered Socrates, his free ideas were too dangerous to be passed to the public at large.
Plato’s myth implies that justice is unfilled in life. Take the case of any sex slaves, human trafficking, or a husband whose four kids and wife are murdered by some lowlife. It is obvious that justice is a myth if it is to be satisfied in this life. A women imprisoned for sex by a captor for a decade is freed, along with 2 other women sex slaves (the Ariel Castro sex crime case); her captor commits suicide 7 months after imprisonment. Was justice served? The judge in this court case did not think so because the judge gave Castro life in prison plus 1,000 years. Justice in the case of grave crimes is a conceit. The impotence of the justice system is manifest. Despite its chief end of “serving justice,” it cannot deliver.https://www.thesun.co.uk/news/10655982/ariel-castros-made-sex-slaves-jealous-of-each-other/
The logic here is straightforward: certain heinous crimes require far more punishment than someone’s life span. I doubt anyone disagrees with this. We object though: because the existence of hades/hell could provide justice doesn’t make it the case that hades/hell exists. The westerner will often take the notion of Karma, bastardize it, make it fit a Western (or Judeo-Christian) moral framework, then gleefully say “instant karma baby,” when someone gets what’s coming to them. The intuition of pop-culture to use Karma in this way shows that many in a subliminal sort of way know that Plato is right. That pesky “heat death (or deprivation) of the universe (2nd law of thermodynamics)” makes even Karma ultimately a labor of futility. The cosmic scales, when the universe comes to its end, even if Karma were true, cannot be balanced. Injustice will reign. If there is no hades or hell, as Plato implies, injustice reigns. Is this an intractable aspect of the problem of evil? Perhaps it is, at least for those that think the universe is all that is.
Someone might not like what Plato is selling, telling him to “stuff it” since it advances that whole Judeo-Christian traditional values thing. Oft repeated objections come in the form of, “creating an idea to coerce the behavior of the living” is worse than letting the injustice and futility of this life stand — at least we can know that. This is what is called question begging, which assumes the conclusion in the premises. Is Plato describing how justice works or is Plato flat out “creating” how he wished justice worked? I am not trying to answer this for you, per se, just thinking through this myself. Another repeated objection is that ideas that are coercive are to be rejected or viewed with suspicion. This is total garbage. All ideas are ‘formative’ and ‘influential’ on who someone is. If I believed that I ceased to exist after death, like a naturalist, such an idea would be “coercive” on me to achieve anything I want right now, to maximize my good perhaps, to construct the world as I see it since I don’t have tomorrow, or even do many “evils” since that whole notion of justice is a myth. Because something forms or influences who I am and how I conduct my life doesn’t make it coercive in the “you are compelled and don’t have a choice” sort of way.
The imperative question Plato is asking is, “Does justice exist?” If we say yes, then how so? Enter the question of Karma; enter the question of hades/hell. Because justice requires hades is not sufficient to say that hades/hell exists. Nevertheless, that hades/hell is required for justice to exist would be one argument, which would become part of a cumulative list of why someone believes that hades/hell is. Why, for instance, is there such an insatiable desire for “justice” to begin with? Why do we see this potently with kids? What’s up with “its not fair dad!” Why did one of the most famous philosophers create the myth of Er? Was he succumbing to this intuitional drive for justice?