I can understand stripping them of the right temporarily while in prison. That's the time in which they pay their debt to society for the harm they're convicted of. Some rights are restricted during that period.
But once it's determined that the debt has been repaid and they're free to live outside and participate in society again, it seems hard to justify them not also participating in the democratic process.
How exactly is taking away an inmates vote "paying me back" for a crime in my community? "Society" isn't actually benefiting here.
Let's go down the list of justifications:
1. Is disenfranchisement rehabilitative justice? No, if anything it's the opposite, preparing them to fail when they get out, promoting ignorance and helplessness instead of engagement in the political process.
2. Is disenfranchisement punitive justice? Not usefully, because the worst criminals won't care anyway, instead it tends to hurt the people who deserve it the least, the people who would otherwise try to work through "the system."
3. Is disenfranchisement a deterrent? No, LOL. Nobody goes: "OK, I was going to commit the crime and risk being caught and shot or jailed for many years, buuuuut then I realized I wouldn't be able to vote, so I'm out."
What's left? Bad reasons, like helping politicians get away with abusive policies.
I know people say this, but I think this framing likely generates anti-prison arguments because it basically doesn’t make any sense. How does being in a cage for X years repay society? It doesn’t. It does keep the harmful person away from society though, which is a very different and useful thing (in many cases, obviously imprisonment for some crimes is dumb).
Being in prison is the punishment. It is not restitution, but as part of the punishment restitution could be imposed. It's hard to pay that restitution while incarcerated though. Some people advocate that just because one has been released from incarceration that they should still not be allowed to vote until any moneys owed have been paid. That could be fines from the court as well as restitution to victims.
But once it's determined that the debt has been repaid and they're free to live outside and participate in society again, it seems hard to justify them not also participating in the democratic process.