Roberto Di Cosmo recently published a work called "Manifeste pour une Création Artistique Libre", the work is not really a manifesto in the traditional sense but more a work about the potential licensing scheme at the Internet age. My blog entry is not about the content of the work itself but more about the non-free license used by the author. On the linuxfr.org website many people (including myself) made comments about how strange is to publish a work about free works while the manifesto itself is not free (licensed under the restrictive CC-BY-NC-ND). The author replies to the questions explaining his rationals to choose the non-free license with an additional "non printing" clause to the CC-BY-NC-ND.
I have a profound respect to Roberto's works regarding the promotion and support to the free software community but I clearly disagree with the facts stating philosophical works must not have any derivative and cannot be a free work. I also know that Richard Stallman disallows derivative work on his various works. If you carefully check the history of philosophical works, there are a lot of essays from various philosophers having some revision due to external contributions (e.g. Ivan Illich has multiple works evolving over time due to interaction or discussions with people). It's true that the practice was not very common to publish about the evolution of the works. But that was mainly due to the slowness of the publishing mechanisms and not by the works themselves.
The main argument used to avoid freeing the works is usually the integrity of the author's work. A lot of works have been modified over time to reflect the current use of the language or make a translation to another language. Does this affect the integrity of the author's work? I don't think so. Especially for any free works (including free software) attribution is required in any case. So by default, the author (and the reader) would see the original attribution and the modification over time (recently improved in the free software community by the extensive use of distributed version control system like git).
Maybe it's now the time to reconsider that free software is going far beyond the simple act of creating software but also touching any act of thinking or creation.