I often feel that some people (xyz-people) who make demands that others should use the most lax, permissive, non-copyleft license possible (like public domain), sometimes just want this, because they (xyz-people) cannot create anything of real value (worth copylefting), but instead want others to put really substantial things under such permissive licenses, so that the xyz-people can simply take that stuff and use it in proprietary software.
Trust me: if you have something substantial, you’ll put it under a copyleft (such as GPL), or have really good reasons to make it public domain.

But if somebody is wining about a “free lunch”, without being able to cook up a fine gourmet dinner himself, then…
… you know…

What a bunch of scared stuff you write.

If a license is incompatible with the GPL, there is a very particular reason for this: a reason that would deprive the recipient (or ensuant recipients) of software some of the freedom-rights that the GPL explicitly ensures.

Since the GPL ensures particular freedoms, and requires them to be upheld for the software-recipients (and for further ensuant recipients to whom they could offer it – copyleft); you cannot combine it with licenses that requires a recipient to relinquish some of those freedoms, or relinquish freedoms to further ensuant recipients of that software.

Such a license is incompatible (with the very reason of the GPL’s existence: to protect freedoms).

Put simply: the GPL protects your freedoms, and makes them unalienable rights to further recipients as well.

By the way: don’t be stupid and put clever useful software into the public domain.
You’ll bang your head, if you see a proprietary company take parts of your software, make a proprietary package from it, that deprives everyone (including yourself) rights to analyze it, learn from it, improve it, etc.
You need to protect yourself:
The right way to do it, is to provide your recipients freedoms, and protect yourself from being ripped off, by requiring your recipients to uphold the freedoms (towards others, including yourself) that you have granted them:
Ensure that they cannot strip off the freedoms; and then bullshit you. Do the right thing: copyleft your code.

Why?

Because while I think there are some noble aspects to the GLP, there are also restrictions and obligations it places on me that I may not agree with. I dont like being told that I cant mix and match code that is OpenSource or even CopyLeft but incompatible. That is a huge restriction that limits my freedom without giving me any additional freedom compared to the public domain.

With Stallman it seems that his big thing is ‘stopping the existence of proprietary software’ from being created. He wants to take advantage of copyright law to make a ‘viral’ license that will force code to even become GLP or become completely incompatible with it and eventually get pushed out…. More realistically, GLP will simply become an Island and proprietary software will continue just fine UNLESS you attack the very idea of intellectual property vs trying to take advantage of intellectual property laws to abolish a specific type of intellectual property.

And while I am no lawyer, it has been suggested that the GLP reads like a contract rather than a license. Can a license actually force you to do something in the future? If I release code under the GPL today, what happens if I dont honer requests to provide the sourcecode when asked?…If somebody I dont like askes me for the code under the GLP I would legally be obligated to give it to them anyway or face legal consequences with my code. If I release it to the public domain then I have no such obligations and can play video games or spend time with my children instead of dealing with companies that want my code, whose ambitions I may not even support.

Stallman wants to destroy incompatible licenses by making the GLP spread to everything it touches. (It will never happen as it will always be possible to create more proprietary software until you challenge the idea of intellectual property itself).

The problem for me is that the GLP, despite being copyleft, now starts to divide code into Islands that are compatible or incompatible. Even if the code is open source and sometimes copyleft even, the GLP simply will not ALLOW me the FREEDOM to mix and match that code. It creates incompatibility, and incompatibility that spreads by association. I cant even create a MODULE using a piece of incompatible code, even if the program would otherwise be functional without that module, depending on how the module works.

So the GLP does create artificial scarcity with its limitations.

Also, the GLP does not ‘make sure the code remains free’. Code that is Public Domain will be free forever, as long as its recognized as Public Domain. It will never become ‘un-free’. Ever.

With the GLP we are actually sacrificing some freedom, such as the freedom to mix code with other licenses (which may have their own pros and cons) in order to tell people that they are not allowed to use GPLed code without it and all derivatives becoming GLP itself….and there are some other fairly good alternatives to the GLP that are incompatible even with version 3, precisely because the GLP is so inflexible in demanding that its the GLP or nothing and no GLP restritions can ever be removed, and no non-GLP restrictions can ever be added.

Sorry, but fuck that. I wont use the GLP. I wont even use the BSD license. The code is going directly into the Public Domain.

In all these cases, the creator of a pattern (invention design, artistic expression, trademark) seeks to use the state’s courts to force other people from rearranging their own property as they see fit: the law prevents me from reshaping my property into a better mousetrap, into an image of MIckey Mouse, into a shoe with a Nike swoosh. In all these cases the law, in seeking to protect rights to non-scarce patterns (and this is what IP laws do have in common), violates the property rights of the individuals it aims at.

Stallman, regarding the Mickey Mouse/scarcity comment, seems to be using scarcity in the “lack of abundance” sense; but scarcity as we use it refers to rivalrousness, the possibility of conflict. If one lives near the ocean salt water may not be abundant so some might say it’s not “scarce”, but if I gather a bucket of it then my bucketful of water is scarce since my use of it excludes your use of it, etc.