Would it be better to have set punishments for crimes (Ex. murder = 20 years imprisonment no matter the circumstances) or to have the punishments be defined with the individual that caused it? Would it also be better for punishments to be more "aggressive" than needed (Ex. littering = 5 years imprisonment)

Not better in any sense I can think of.

On the "set punishment" question: I'm struggling to think what the point of inflexible sentencing laws would be given that the circumstances can vary in ways that seem clearly to be relevant.

On the second question: the way you phrase it seems to provide the answer. If a 5-year sentence for littering is more aggressive than needed, then it's more aggressive than needed.

Of course, if we had really harsh penalties for minor offenses, very few people would commit them. But the ones who did would be punished much more severely than their transgressions would justify. That seems like a high cost. Also, the citizenry would live in fear---another high cost. Mistakes in the judicial process would lead to innocent people bearing burdens that would be unreasonable even if they were guilty, and there would be reason to fear that laws like this would be abused and used to target unpopular minorities; that already happens as things stand. It's hard to see how what we're imagining could do anything except make things worse overall.

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