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The definition of "Free Software" from the Free Software Foundation:

“Free software” is a matter of liberty, not price. To understand the concept, you should think of “free” as in “free speech,” not as in “free beer.”

Free software is a matter of the users' freedom to run, copy, distribute, study, change and improve the software. More precisely, it means that the program's users have the four essential freedoms:

  • The freedom to run the program, for any purpose (freedom 0).
  • The freedom to study how the program works, and change it to make it do what you wish (freedom 1). Access to the source code is a precondition for this.
  • The freedom to redistribute copies so you can help your neighbor (freedom 2).
  • The freedom to distribute copies of your modified versions to others (freedom 3). By doing this you can give the whole community a chance to benefit from your changes. Access to the source code is a precondition for this.

A program is free software if users have all of these freedoms. Thus, you should be free to redistribute copies, either with or without modifications, either gratis or charging a fee for distribution, to anyone anywhere. Being free to do these things means (among other things) that you do not have to ask or pay for permission to do so.

The definition of "Open Source Software" from the Open Source Initiative:

Open source doesn't just mean access to the source code. The distribution terms of open-source software must comply with the following criteria:

  1. Free Redistribution The license shall not restrict any party from selling or giving away the software as a component of an aggregate software distribution containing programs from several different sources. The license shall not require a royalty or other fee for such sale.

  2. Source Code The program must include source code, and must allow distribution in source code as well as compiled form. Where some form of a product is not distributed with source code, there must be a well-publicized means of obtaining the source code for no more than a reasonable reproduction cost preferably, downloading via the Internet without charge. The source code must be the preferred form in which a programmer would modify the program. Deliberately obfuscated source code is not allowed. Intermediate forms such as the output of a preprocessor or translator are not allowed.

  3. Derived Works The license must allow modifications and derived works, and must allow them to be distributed under the same terms as the license of the original software.

  4. Integrity of The Author's Source Code The license may restrict source-code from being distributed in modified form only if the license allows the distribution of "patch files" with the source code for the purpose of modifying the program at build time. The license must explicitly permit distribution of software built from modified source code. The license may require derived works to carry a different name or version number from the original software.

  5. No Discrimination Against Persons or Groups The license must not discriminate against any person or group of persons.

  6. No Discrimination Against Fields of Endeavor The license must not restrict anyone from making use of the program in a specific field of endeavor. For example, it may not restrict the program from being used in a business, or from being used for genetic research.

  7. Distribution of License The rights attached to the program must apply to all to whom the program is redistributed without the need for execution of an additional license by those parties.

  8. License Must Not Be Specific to a Product The rights attached to the program must not depend on the program's being part of a particular software distribution. If the program is extracted from that distribution and used or distributed within the terms of the program's license, all parties to whom the program is redistributed should have the same rights as those that are granted in conjunction with the original software distribution.

  9. License Must Not Restrict Other Software The license must not place restrictions on other software that is distributed along with the licensed software. For example, the license must not insist that all other programs distributed on the same medium must be open-source software.

  10. License Must Be Technology-Neutral No provision of the license may be predicated on any individual technology or style of interface.

These definitions, although they derive from very different ideologies, are broadly compatible, and most Free Software is also Open Source Software and vice versa. I believe, however, that it is possible for this not to be the case: It is possible for software to be Open Source without being Free, or to be Free without being Open Source.

Questions

  1. Is my belief correct? Is it possible for software to fall into one camp and not the other?
  2. Does any such software actually exist? Please give examples.

Clarification

I've already accepted an answer now, but I seem to have confused a lot of people, so perhaps a clarification is in order. I was not asking about the difference between copyleft (or "viral", though I don't like that term) and non-copyleft ("permissive") licenses. Nor was I asking about your personal idiosyncratic definitions of "Free" and "Open". I was asking about "Free Software as defined by the FSF" and "Open Source Software as defined by the OSI". Are the two always the same? Is it possible to be one without being the other?

And the answer, it seems, is that it's impossible to be Free without being Open, but possible to be Open without being Free. Thank you everyone who actually answered the question.

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closed as not constructive by Yannis Rizos Aug 15 '12 at 15:29

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You may want to take a look at the FSF Approval and OSI Approval columns in Wikipedia's license comparison matrix. Caution: Licenses that have not been reviewed are also listed as "No". –  netvope Sep 22 '11 at 5:13
    
This question is being discussed on Meta. –  Yannis Rizos Aug 20 '12 at 7:50
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7 Answers

up vote 12 down vote accepted

According to Wikipedia, any software licensed under the NASA Open Source Agreement is open source, but not free, so that would be one example.

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Any license that doesn't include the "viral" clause is open source, but not enforced "free as in speech." The MIT and BSD licenses are two, among many others. –  Robert Harvey Nov 27 '10 at 20:54
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@Robert Harvey, non-copyleft ("viral") licences such as X11, modified BSD, or WTFPL most certainly are Free (and Open). Derivative works may or may not be Free (or Open). –  TRiG Nov 27 '10 at 23:51
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@Robert, I didn't know the answer to the question I asked. That's why I asked it. You appear to be trying to answer a different question, which I didn't ask. –  TRiG Nov 28 '10 at 0:09
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He accepted the only answer that answered the question... –  alternative Nov 28 '10 at 1:05
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@Robert, @mathepic, Try reading the clarification note I've added to the question. –  TRiG Feb 8 '11 at 21:28
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The answer according to the free software foundation is yes. See http://www.gnu.org/philosophy/categories.html and http://www.gnu.org/philosophy/open-source-misses-the-point.html

Extract from first link, bold added by me:

The term “open source” software is used by some people to mean more or less the same category as free software. It is not exactly the same class of software: they accept some licenses that we consider too restrictive, and there are free software licenses they have not accepted. However, the differences in extension of the category are small: nearly all free software is open source, and nearly all open source software is free.

Sorry, don't have examples.

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The question was about whether there are licenses that are Free but not Open Source or vice versa. It wasn't about the philosophical underpinnings of each. –  David Thornley Feb 8 '11 at 22:40
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The first link is to a Venn diagram that, shows that the free software foundation believes that there is. –  richard Feb 8 '11 at 23:12
    
Thanks. And I knew there was some Open which wasn't Free. I didn't know there was any Free that wasn't Open. I'd love to know which. –  TRiG Feb 9 '11 at 10:48
    
I still haven't found any Free Software licences which are not Open, but I have found a Free Software license of which the OSI does not approve: WTFPL. This license is very clearly an Open Source license, but the OSI does not recommend it. (The FSF includes it in its list of Free Software licenses.) –  TRiG May 22 '11 at 1:28
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I'm late on this one, but the conclusion by the questioner:

And the answer, it seems, is that it's impossible to be Free without being Open, but possible to be Open without being Free. Thank you everyone who actually answered the question.

is not true. There is the CeCILL License v2, which is Free (FSF-approved) but not Open. Seems it was rejected by the OSI in 2005, so CeCILL is not Open Source.

Just thought I would point this out, since no one here had mentioned CeCILL.

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But the OSI doesn't approve of WTFPL either, even though that's definitely an Open Source license. I think the OSI maintains a list of "recommended" or "approved" Open Source licenses, which doesn't necessarrily mean that a license not on that list is not in fact Open. So that means that CeCILL may or may not be Open. I'll look into it. Thanks. –  TRiG Feb 13 '12 at 12:40
    
In fact, the FSF says that CeCILL is compatible with the GNU GPL. That's an Open license, so presumably CeCILL is also Open, even if the OSI doesn't recommend it. Presumably. IANAL: Don't quote me on that. –  TRiG Feb 13 '12 at 12:43
    
CeCILL was rejected in 2005 because of "unclear terms" which were not clarified; and then considered again in 2010 but it seems that the terms still weren't clarified. Maybe one day. It's not been formally declared non-Open, though. The WTFPL was rejected in 2009 not because it was non-Open, but because it was "redundant to the Fair License". –  TRiG Feb 13 '12 at 17:17
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The OSI application to list a license includes (or included) something on what that particular license did that the others didn't. Therefore, there can be licenses that satisfy the Open Source principles that aren't OSI-certified Open Source licenses, and it may be useful to clarify what definition one is using. –  David Thornley Feb 13 '12 at 22:39
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The FSF free software conditions refer to the software. The OSI open software conditions refer to the license of such software. This is an important legal distinction.

For instance, under US law, there is no free software. Export laws restrict your freedom to export software to North Korea and Iran. However, as these are not restrictions in the license (but rather in law), these restrictions do not affect the Open status.

Of course, these subtle distinctions are often overlooked by the proponents of Open Source. The FSF subtly acknowledges them. When they talk about export controls, they do restrict themselves to "Free Software Licenses", not "Free Software".

The other way around is also possible. E.g. if you're living in a country that does allow Free Software, a Free Software license may violate the "Integrity of The Author's Source Code" and not be Open. That's just not one of the enumerated freedoms.

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I think that "Open Source", as defined by OSI, and "Free Software", as defined by FSF, are very much the same thing. Maybe a clever lawyer could craft a license that is just one of those, but every real-life license is either both or none.

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Any license that's free software is open source, but there are several licenses (like the NASA Open Source Agreement) that are just open source and not free software. –  Joe D Dec 24 '10 at 18:25
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It is possible for software to be "Open Source" but not "Free Software" (free in etiher sense)

The reverse I think is not possible, Freedom 1 requires Source Code.

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Thanks. Do you have any examples? –  TRiG Nov 27 '10 at 17:56
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I am sorry I think I misunderstood "Open Source" in the general sense, wherein some-one (not necessarily the Open Source Initiative) provides you source code. –  khalooo Nov 27 '10 at 17:59
    
e.g. If I am an embedded-sys guy who uses a third party chip whose vendor has given me its device driver source code for my sys specific tweak. It is open source (in generic sense), but not meant for re-distribution or free give away –  khalooo Nov 27 '10 at 18:01
    
I meant "Open Source as defined by the OSI" and "Free as defined by the FSF". –  TRiG Nov 27 '10 at 20:06
    
-1 for miss-understanding/miss-representing the terms Open Source and Free Software (answers and comments). To clarify Open Source ≠ freedom 1, the definition of Open Source takes a page and is not summed up in the name. Open Source is an abstract noun as is aardvark, if you don't know what it is the name won't help. Free Software ≠ give away. Free as in freedom. –  richard Aug 15 '12 at 14:24
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Well, I think the definitions are all a bit confused, so my concept is: Open Source means you can read the source. It doesn't mean you can copy it.

Free means you can do what you like with it. GNU GPL is not a free licence, it is, in many ways, more restrictive that a typical commercial licence. In particular, the lack of freedom inherent in GPL is there precisely to create a great divide, to make people choose between copy right and left. Its purpose, quite clearly is to start a war (which it expects to win!).

I am a developer of Open Source Free software. I use GPL'd tools to construct it, but I cannot include any GPL'd software in my system, because my software is genuinely free. Meaning free for any use. Copy it, modify it, publish the changes or not as you see fit, sell it, use it in commercial software. There are many FFAU licences (MIT/BSD being the original ones I believe).

GPL was really important for getting the Open Source movement going but it is now killing it.

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I'm not very interested in your definitions. I'm interested in the definitions of the OSI and the FSF. –  TRiG Jan 24 '11 at 10:37
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-1, the GPL is not killing the Open Source movement. There are alternative licences to pick from anyway. Also, if all the code you want to include is GPL'd, then that particular licence is actually helping produce good software by definition, isn't it? –  Andres F. Feb 8 '11 at 21:38
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-1 for extraneous ranting and using nonstandard definitions when the question uses standard ones. –  David Thornley Feb 8 '11 at 22:39
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