[sph]

A "do not use this software for evil" license is morally identical to one that states "only use this software for evil".

The best licenses are those that just say "there you go, do whatever you want, but don't fucking sue me." (That means pretty much all mainstream open source licenses)

[OkayPhysicist]

No, the best licenses are the ones that say "there you go, do whatever you want, but pay it forward", like the (A/L)GPL. It's an astute solution to the free-rider problem inherent to large gift economies: once you pass the scale where individual reputation is the driving factor in engagement with the economy, it's easy to accumulate a parasitic group that takes from the generosity of others, but not only offers nothing in return, but expands itself to deprive more resources from the economy at large.

Copyleft licenses are a defense tool against those parasites. You're free to use the software, anyway you like. You're free to modify the software in anyway you feel fit. The only restriction is that if you choose to share it with others, than you grant them the same freedoms you've been so generously given yourself.