>Do you happen to know of a licence that has anything like a "can only be used for the benefit of humanity" clause?
A terrible idea for a number of reasons (in terms of legal enforceability, unintended side effects, and more). The following two articles do a good job of explaining why such a license really isn't practical:
Yes, the unintended side effects of HESSLA (sibling comment) were a surprise for me to read about.
Thank you for the links - I'd not heard of the Hippocratic License but the criticisms are interesting.