Should Criminals Get Taxpayer-Funded Viagra?

Because it is in fact different, in many various and obvious respects. That is the key point. Refusing to provide free Viagra is not justified solely because a rapist used his penis to commit a crime (although that’s part of it) - it is also justified because the ability to get an erection is not even remotely comparable in importance to the use of one’s arms.

It’s the only justification for singling out sex offenders, and it’s a pretty weak one.