This license gives you the freedom to modify the work and redistribute it, if you do so under the same license.
This "freedom" emboldens the FreeSoftware ethic, by requiring all users of the CopyLeft software to give back to the community, rather than allowing certain individuals (typically software developers) to not give back to the community by distributing their modifications as proprietary. Because of the requirement by the copyright holder to keep using this licence, these licenses are often called "freedom-insured", as opposed to the combative term "viral".
For the official FSF statement, read their page on licenses:
Whether copyleft works are works for the public good is debatable. On one side, there's the argument that anyone can contribute and use the works. On the other is the argument that some situations may require or be facilitated by private development and such developments may be inhibited if copyleft is required. For example, the use of trade secret components may prohibit the disclosure typically required by a copyleft license, so a writer may be barred from an otherwise useful resource. In such situations, the copylefting of a component denies parts of society the benefit of the work. As a result, it's less well suited for pure public good projects than less restrictive licenses.
One classic example where trade secrets would have been required was a DVD player. The player would need to use the trade secret CSS method and disclosure of the required techniques is covered by a contract prohibiting disclosure. Hence, it was impossible to write a copyleft DVD player.
In effect, the copyleft license is intended to create a gold mine of useful tools but only let in those of the view that source code should be public.
The gold mine can be partially poisoned by using non-copyright mechanisms, such as patents, to allow use of copyleft a material within the scope but contrary to the spirit of the license. The patent holder can then publish the work as required by the license but still use patent law to prohibit others from using it.
It is possible (but not encouraged) for contributors to a wiki to explicitly tag their contributions as copyleft - see PermissionTagging.
Many of those who promote CopyLeft licenses view the term "viral" as a misleadingly pejorative term, since it implies the existence of an infectious agent. However, CopyLeft only applies to derived works, and cannot "infect" works that do not rely on previously existing copylefted works. It is more appropriate to say that the terms of CopyLeft are inherited by any derivative works.
The concept of what constitutes a derived work in CopyrightLaw is not linear, however, and it need not be an "inherited" relationship. This leads to some confusion. When mixing two sources, one GPL and one not, it is entirely subjective whether the final derivative will be considered a derivative of the GPLed source or the other. It will depend on the amount, character, jurisdiction, court, and the persuasiveness of the lawyers present. Either way, the non-GPLed source can remain non-GPLed and kept secret if the owner so wishes. They will just be in violation of the terms of the GPL copyright license, and subject to some liability. After all, if the derivative is considered from the non-GPLed source, then it will be using the copyrighted GPLed source without permission. If the derivative is considered from the GPLed source, then it is not following the terms of the license.
It's the latter case that leads to infection, perhaps, if the judgment deems that the source be released. However, that suggests that so much of the derivative came from the GPLed source that it is essentially a descendent, and thus similar in character. In some subjective contexts, it makes sense to demand the release of the source code.
It's also a misconception to believe that incorporating non-GPLed code into a GPLed project unknownst to its owner will taint the original source. For instance, a large text, like the Linux kernel, is not carefully controlled. Well-intentioned contributors, or even malicious contributors, might incorporate a seemingly innocuous snippet from a non-copylefted source. However, the non-copylefted source is not immediately copylefted. Rather, the Linux kernel would be in violation of the copyright of the non-copyleft source. The question of who is ultimately liable for this screw up has been a hot issue in 2003, given the [SCO vs. Linux] fight.
One solution to the problem is to assign all the copyrights to the copyleft project to one entity. The GNU project demands that all contributors sign their copyrights to the FreeSoftwareFoundation before they accept the changes. This means that the liability is clear: whoever submitted the proprietary code was responsible. It also means that one undemocratic (as the FSF is not accountable) party has a monopoly on the IntellectualProperty of the project, which is a paradox the project has yet to resolve.
Another problem is that some people do not want to make copyleft derivatives of copyleft works. The advantage of having one copyright holder for the project is that more nuanced licensing regimes can be employed. For instance, some have tried to work around these restrictions by dual licensing works with both a copyleft license and a proprietary (or other) license. In those cases (such as for the Qt library, or MySQL?, OpenAFS?, et al) the code is forked into proprietary and non-proprietary branches. It's important to note that the copy of the work that with a non-exclusive unlimited CopyLeft license will still always remain copylefted regardless of what's happening with the proprietary branch.
Furthermore, the licensees of the proprietary version do not possess a copylefted work so they may not possess similar rights; however, if the copylefted work is made public, the licensees of the proprietary version may also switch to the copylefted version (if they can get it). though it's important to understand that these are two distinct sources, even if mixed together. Derivations made by third parties from the proprietary license stream remain in parallel to any derivations to the copyleft stream.
An interesting point regarding dual licenses should be mentioned. So long as one branch remains open to it, code can be merged across the forks. Not that that is always going to be trivial to do, but it is an option. Examples of this are given in Rick Moen's "Fear of Forking" essay. In culture and community terms, cross-pollination can occur as people move around among projects. Forking needn't be either absolute nor forever. What does need to happen (depending on the license) is some accomodation from one release branch to the other--this might be as simple as a time-delayed release of code from the proprietary branch into the copyleft branch under a the same dual license as the parent code base. However, this puts the copylefted branch at a disadvantage, as it remains in the shadow of the proprietary branch, thus making it more difficult to grow a vibrant community around the copyleft branch. An interesting question arises too when a novel or vital change is made to the copyleft branch; how does the proprietary branch fold those changes in? Sometimes (typically) the copyleft license provides the company with the right to incorporate public changes into the proprietary branch.
The SCO case isn't a good example. Thus far, I've seen nothing but wild claims without a shred of evidence.
It's as carefully controlled as any comparable body of propriety software. Furthermore, it can be audited by anyone who wishes to do so. Sticking with your SCO example, there is widespread suspicion that SCO may have incorporated GPLed Linux code into UnixWare?'s "Linux Kernel Personality" features. Short of a court battle, there is no way to independently determine if this is the case.
If this were the case, then it is the propriety software developer that has the source code control problem, not the free software/open source developer. However, its not possible to force the GPL (for example), any more than unintentionally including sections of propriety code forces you to immediately pay royalty fees. Once such violations are brought to the attention of the person(s) responsible for the body of code, they can be removed. The GPL can only apply if the person agrees to its use by continuing to use the copylefted code in question. -- StephenGilbert
The argument that CopyLeft makes the software free as in speech is a huge category error. First, it is not the software that is being oppressed as it is an artifact, not a person, and thus it cannot be freed. It can only be "free" (an overloaded word) as in beer (cf. InformationWantsToBeFree). Second, the person who wrote the software does maintain his or her freedom of speech because the programmer may publish what he or she chooses without interference by the state. Note that statutory forcing the publication of source code is an impingement of freedom of (non-)speech.
Freedom of audience is more accurate, and more accurately freedom of audience-participator. It brings a human back into the equation, and it brings the correct human back into the equation. There is no ethics of audience-participator yet, but there are ethics of consumer-producers available which are very similar. I think it would be valuable to contrast Marxism with copyleft, even if the parallel will inevitably fall apart due to the differences between software and other types of produced goods. The FreeSoftwareFoundation is itself very Marxist (cf. EatSushi).
Software is fundamentally different from passive text in ways that explode the model of intellectual property. Intellectual property attempts to frame ideas as commodities, but software is not a commodity. Software is cybernetic; it has the ability to take action on its own. It has a power that text does not, as text is mitigated by people, and thus remains within social control. The problem with software is that it is non-negotiable, or at least intractably expensive to negotiate, which is why source code is necessary. Note that complicated machines are also non-negotiable, such as a modern car engine, except blueprints and maintenance manuals are published to mechanics, but those are limited. They explain how to swap a broken part for another rather than attempting to fix what may in fact be a simple failure to repair. Of course, we have patents to help close the gap of what is published in maintenance manuals and what is kept a secret. Basically, it's new for something to be both speech and machine.
The real question is a) how does copyleft/copyright work with passive texts, b) how does copyleft/copyright work with social texts? And that depends on how public or private the thoughts in those texts are (cf. LifeInText). And also, to consider in the short term what we should do now under the existing legal and technical structure, and what we should build or laws to change in the long term. I think it's important to understand where "Marxism" is a good answer, or if you prefer the less loaded terms communal or co-operative or sharing solutions. Is an industrial-military complex the right answer or an ashraam? Both are successful solutions in their contexts. -- SunirShah
The "free speech" argument is that when I copy or modify what you write, that's an act of speech, and thus copyright restrictions are restrictions on my freedom of speech. FairUse is a partial remedy to this, but copyleft is arguably a stronger remedy. However, "freedom of audience" is perhaps a better way to consider the issue.
Removing copyright protection is an example of a anarcho-communist change: anarchist because it removes governmental interference in the act of copying, communist because the consequences of that removal are to increase equality. Contrast authoritarian-communist changes like forcing programmers to publish source code, or banning technological Digital Rights/Restrictions Management, or centralised funding of those who create good content. --MartinHarper
For the sake of simplicity, I will assume for the moment that freedom of speech includes the freedom of expression. The freedom of audience is a limitation on the freedom of speech of the author. The right to copy and modify an expression has a dilutory effect on the expression. This may result in subverting the original intent of the author in the author's name, as is frequently the case in academic citations who do not read the work cited. In a more malicious case, it leads to the PhonyFlood scenario by a hostile entity such as an oppressive government, which is a serious violation of the freedom of speech. Further, diluting the economic value of artificial scarcity limits the freedom of expression of the author by making it dangerous to publish the idea; in economic terms, the author is not free to express the idea, which might have involved significant economic investment. Since limiting the freedom of the author has a consequent and necessary limitation on the freedom of the audience (as it is dependent on the author), it is not reasonable to argue that the freedom of the audience exceeds the freedom of the author. Note the author remains free to free the audience. -- SunirShah
Your argument seems to be that by publishing now, the author is giving up the benefits that might acrue from publishing later, and thus it is risky: it has an "opportunity cost". However, this is the case with or without copyright law. For example, by writing an essay online, I can no longer sell exclusive rights to that essay to a third party: that is a risk associated with writing online, and no amount of DefensiveCopyright can eliminate it. If I publish in a world with no copyright law, then I have less control over my work, which increases risk. However, in such a world the benefits from publishing are reduced, which decreases risk. My feeling is that the result would be a net decrease in the opportunity cost associated with publishing right away.
I don't care much about dilution, because I don't believe in a right to influential free speech. The authors words may have less impact because they were badly written. They may have less impact because the author lacks recognition. They may have less impact because they are unpopular, or misinterpreted. They may have less impact because they are diluted by copying and modification. They may have less impact because you delayed publshing and someone else came up with the idea independantly. Do these things cause a problem? --MartinHarper
They do cause a problem because popularity is not a measure of quality. I give you SlashDot. We could argue abstractly that it is in fact high quality because it is popular, but it would still actually be low quality. There are economic equations to describe the relationship between quality, cost, and market share, and they are in tension. Free stuff is usually very popular, though you get what you pay for. (I could insert here my apparently popular diary entry on the Age of Vanilla.) Very good stuff is also popular, but that costs a lot of money to produce. It also requires practice, which is why we have a large market of mediocre works. It's important to pay for talent as well, as not all labour is equal. It's not legitimate to complain about how much a talented individual earns a year, say how much your favourite sports star makes. It's only legitimate to complain about how much you are willing to pay.
You should care about dilution because there are alternatives to publishing on the open 'Net, just as there are alternatives to standing on a SoapBox in Hyde park in London. For one, one does not publish anything substantial on anything less than paper. But if paper eventually dies, somehow, then forms of GatedCommunity emerge to maintain scarcity (e.g. streaming audio vs. downloadable audio), which is an actual reduction of the freedom of audience from paper. The stronger the FairUse provision (up to CopyLeft), the stronger the reaction for control. FairUse was a good compromise because it limits the amount of copying to what is necessary to generate derivatives whilst requiring attribution of the source. FairUse of software is very complicated subject, but software is not text for which we have a good system in place.
However, I will contend that the digital network technology intrinsically itself to this scenario. The argument that it will lead to the free and open society is ludicrous because no one wants a free and open society if it involves them giving up something. The only things that are available free on the Internet (legally) are things that people have either some desire to make popular, such as commercial giveaways, government documents, or PoliticalAction; or popcorn thoughts like pop culture, movies, trivia, and political rants. It's consequently no surprise that on the 'Net where people talk to other people on the 'Net, the political thinking is dominated by those who want free stuff and it does not incorporate the feelings of those who produce content, and tends to be very hostile towards professional content producers who don't bother publishing on the 'Net. The economics of information production hasn't changed much; simply that because InformationWantsToBeFree the economics of information distribution leads to more care. The music industry made a giant mistake going digital, but they were early adopters. The print industry is taking a long time to do this, not the least because they see music downloading as something they don't want to jump into. Good! The print industry needs more capital, not less. At least I live in a country where the print industry went from having not enough capital, to a golden age, and now to a craterous rancid landscape today over the last ten years, and in Canada we are always in need of protection against American culture.
I'm against the PoliticalAction to supplant copyright, but there is a better answer where copyleft is selectively chosen for certain tasks, and copyright remains useful. Ultimately I agree that copyright should not survive because we are moving past the age of print. We didn't need copyright in the age of manuscript. Who knows? We may use TechnologySolutions (e.g. digital rights management) rather than a LegalSolution, and that is bad because the public will no longer have a say. -- SunirShah
The threat of TechnologySolutions is a hollow one. Certain content creators will try to use DRM on copying regardless of the legal situation, and regardless of how many people pay attention to copyright. In theory the public could elect a government that bans DRM, so they will still have a theoretical say, just like now. In practice political parties will be in the pockets of business , just like now, so that won't happen. Companies like scarcity and monopolies, so I know which way their money will be voting.
I'm well aware that abolishing copyright would reduce the total amount of quality content produced. However, my contention is that the total amount of quality content accesible to the average person would increase. I value people over content, and thus I wish to maximise the amount of quality content available to the average person. The total amount of quality content does not, in itself, increase the sum of human happiness, so it is not important in itself. --MartinHarper
At the heart of this is a collective vs. individual argument, I think. TheIndividual only cares about his or her own benefit, but there are collective interests that override (at least I think so), such as maintaining an environment where each individual is free to take care of his or her own benefit. So while the person you concern yourself with will bathe in the content, in the long term, the society which creates that content for the person will be harmed, which will in turn harm the person.
There are already better economic tools to publish quality content. The legal solution of abolishing copyright will result in less (contemporary) quality content being made available to the public, which kills a democracy. It's more valuable to focus on creating, editing, and distributing good material cost effectively, which strengthens a democracy. I don't feel that just because you are poor, that entitles you to steal from the rich provided you have a fair opportunity to become rich yourself. There is a balance to SocialCapitalism where talent is rewarded and opportunities are provided.
I might remind you that library funding is being cut almost everywhere; why? That is the social institution that frees information. Given the current industry amalgamation, one could surmise a fair law that said every public library has the right to maintain one copy of a material at the minimal cost of medium production and distribution. Then you would have to negotiate with others in your co-op which books to buy, but so it is. -- SunirShah
I don't believe it's individual vs collective. Let me put it more formally. Let us suppose that every book is read the same number of times, and nobody reads the same book twice. So, there are B books produced, each of which is read R times. Thus "literacy" (L), the total amount of reading done, is equal to B x R. We want to estimate U: the utility of all books to the collective. A good first estimate is U=RB=L. A book imparts value by being read. An unread book has no value. The more times a book is read, the more value it imparts. However, as you rightly point out, the collective values specialisation and diversity amongst its members - it doesn't want everyone reading the same book. So let us try to factor this into our estimate by guessing that U=LB. The details don't matter for the purposes of this argument.
Abolishing copyright will dramatically reduce the price of the average book, by removing the artificial monopoly. This has two effects. It reduces B, by an amount determined by the price elasticity of supply. It also increases L, by an amount determined by the price elasticity of demand. In other words, fewer people will write books if it isn't profitable, but more people will read books if they're cheap. If the benefit from increased L outweighs the costs from decreased B, then abolishing copyright will benefit society. My feeling is that this is the case. You presumably believe the opposite. Isn't it that simple? --MartinHarper
No, because literacy isn't as simple as reading a quantity of words. There are good books, bad books, and DadaDodo. Literacy is a duality what you already know and can understand, and what you take in. We speak of different literacies, like computer literacy, methodological literacy, word literacy, because they each require a different set of training. The training for the most elite kind of literacy is very expensive, costing at least thirty years of a human life and a few million U.S. dollars--that is the literarchy, if you will.
Popular literacy derives most of its central ideas from the content production by these highly developed individuals, except it diffuses it through a large body of text, often changing the idea in the process, and building smaller mountains from it. This is a volcano effect, and I believe it must be supported, partly because I am striving to become the volcano not just some mediocre hill. Popular works only convey the essential idea in an appealing way. The Matrix the movie was very popular, but it regurgitated less accessible source works in philosophy. If the world was only form, then copyright would be meaningless, but content is critical as well. I mean real content; an actual improvement in our understanding of the world.
The situation before copyright was very bad for this process. The letter writing societies kept their ideas very private. Now we can publish freely for the benefit of all humanity.
It's a terrible mistake to assume that raw materials are the same as manufactured products. There may be $40 of steel in a car, but a car is worth $30 000 USD for a reason. Each character on a page may be cheap, each byte on the wire may be cheaper, but the assemblage of bytes and characters in an intelligent way is very very expensive. An infinite number of monkeys do not recreate Shakespeare. And you can read the stream of output of an infinite monkeys, but it will not increase your literacy.
Literacy is about understanding. -- SunirShah
See also CopyLeftCommunityProblems.