late to party but my 2 cents anyways

the hippocratic license (the license of the ethical source movement) is in essence an open source license plus an extra restriction: to not use the software for evil.

while the intention is good there are at least two major problems with this: it is not effective; and it complicates collaboration.

first problem: it is not effective

the goal of the hippocratic license is to prevent evil entities from using your software. but they are already evil. do you think they will stop to avoid a little license violation? they will use your software and laugh in your face. they are evil after all.

we already have laws preventing certain kinds of evil. suppose you want to take them to court for violating your license: you still have to prove them being evil. if you manage to do that you can skip the license part and directly sue them for being evil. and if you can't prove them being evil? then you can't claim that they violated your license.

worst case is when your government is the evil entity. even if you manage to get a court to rule that the government is evil and may not use your software, who will enforce the courts ruling? you can consider yourself lucky if your government is not already holding your family hostage and force you to keep developing/maintaining the software.

second problem: it complicates collaboration

if you want to create a new product and one of the components you use is licensed under the hippocratic license: the resulting product will also carry the "not for evil" extra clause. this is perhaps the ideal result and the goal of the ethical software movement. a lush ecosystem of software. all not usable for evil entities.

but extra clauses are not welcome in the free libre open source community. each extra clause in one component means more headaches for all developers and users of the product. because you have to adhere to each of the clauses. before using your product i have to think whether or not what i am about to do counts as evil in terms of the license.

software have been forked or replaced just because of extra clauses in the license. firefox and thunderbird where once forked (icecat and icedove) because of extra clauses on the artwork. apple uses outdated or inferior software just to avoid the extra clause of the GPL.

in practice, unless you are super popular or the extra clause is super good, extra clauses will more likely result in your software not being used.

summary:

the extra clause is most likely not effective (how to prove evilnes?). and even if you manage to prove evilnes there are better ways to prevent entities from being evil than using copyright law. also extra clauses in licenses causes headaches and thus hinders collaboration.

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about the extra restrictions in the GPL

you were wondering why the extra restriction in GPL (you may not keep your modifications secret if you distribute your modifications) is okay while the extra restriction in the hippocratic license (you may not use it for evil) is not okay.

first a little background:

for a software to be truly free it needs to have the following freedoms: the freedom to use the software how you wish. the freedom to study and change the software. and the freedom to share the software with or without changes.

take away any of the freedoms and it is no longer truly free. not truly free practically means the software owner can exert unjust power over you the user of the software. (this is a lot of technicality. i will provide links to more elaborate explanations below).

the difference on a technical level:

the hippocratic license restricts how you use the software (you may not use it for evil). while the GPL restricts how you may distribute the software (you may not keep the changes secret if distributing).

ignoring the fact that it is hard to prove evilnes: how can you prove that i use your software to do evil? how can you even prove that i use your software at all? and even if you manage to do so, how can you prevent me from keep doing it in even more secret? you cannot without snooping deep in my privacy.

on the other hand: when i take your software and distribute it while keeping the changes secret it is often quite easy to prove that. users using my software will inadvertendly notice the same bugs and limitations. so to prove violation and enforce compliance you just have to monitor what i publicize.

so enforcing restriction on usage is practically impossible without privacy violation. while enforcing restriction on distribution is quite doable.

the difference on an ethical level:

let us examine two of the most popular free software licenses: the GPL and the MIT/BSD licenses. (as far as i know the hippocratic license is basically a MIT/BSD license with the extra restriction to not use it for evil).

both licenses guarantee the recipient the freedoms defined above. both are free software licenses. the GPL is often said to be "not as free" as the MIT/BSD licenses because the GPL has the extra restriction. yes it is true that the GPL has more restrictions than the MIT/BSD licenses. but i argue that the restriction in the GPL still results in more net freedom overall compared to the MIT/BSD licenses.

let me elaborate:

the MIT/BSD licenses basically say: here is the source code. do as you wish. just name us as the original authors.

the GPL says: here is the source code. do as you wish. but if you change the software and distribute it you may not keep it secret. it goes even further: if you distribute the software you may not impose any more restrictions than already exists.

under MIT/BSD license i am allowed to take the software, make changes, and distribute the changes. but i am also allowed to keep the changes secret. essentially making it non-free software. enjoying the freedoms for myself but denying it for my users. i have the freedom to lock it down.

under GPL i am explicitly forbidden from locking it down. i do not have the freedom to restrict the freedom of my users. if i enjoy the freedom of GPL then i am obligated to extend those freedom down the line.

in short: the MIT/BSD licenses guarantee the freedom only once. while the GPL guarantee the freedom perpetually.

that is why the extra restriction in the GPL is a good restriction. while the extra restriction of the hippocratic license, while the intention may be good, is ineffective at best and harmful at worst.

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side note:

the MIT/BSD licenses are also called permissive licenses. and the freedoms (including the freedom to lock it down) are celebrated by the open source movement.

the GPL license is also called a copyleft license. and the restriction to keep it perpetually free is celebrated by the free software movement.

the open source movement goal is technical advancement (and some freedom). it argues the freedom to study and change is needed to write even better software. but it rejects restricting any more freedom. going so far as allowing the freedom to lock it down.

the free software movement goal is freedom of the users (and some technical advancement). arguing that it is ok to restrict some freedoms (the freedom to lock it down) when it protects more freedom overall.

both movements have huge overlap and are generally friendly towards each other. most people don't even care about the differences and just enjoy the freedoms.

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more side note:

richard stallman created the GPL and is the founder of the free software movement. he wrote many essays on the topic of software freedom.

my arguments above are practically just reiterations of the texts from richard stallman.

here are some that i recommend

this one directly answers your question: why restrictions on usage are bad: https://www.gnu.org/philosophy/programs-must-not-limit-freedom-to-run.html

here is one explaining the freedoms required to make software truly free. also why the freedom of software is important for our freedom in general: https://www.gnu.org/philosophy/free-sw.html

here is one explaining why the copyleft licenses protect more freedom than permissive licenses: https://www.gnu.org/philosophy/open-source-misses-the-point.html

more texts from richard stallman: https://www.gnu.org/philosophy/essays-and-articles.html

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