There have been two posts about C# and mono on PlanetKDE this week (e.g. Richard and Andreas). The comments on Andreas' entry are quite cogent, as are those replying to Richard, but it deserves a wider audience. As far as asking RMS at Gran Canaria this weekend, it's worth a shot if you abstract the question away from specifically-C# and specifically-mono.
At issue is the notion of a Free Platform. Or perhaps an unencumbered platform. The latter is a weaker term because it does not stress the Freedom aspect of the software we write, but it might better express the uncertainty around what constitutes such a platform. There are many things that might encumber a software program or software platform. Dictionary check:
encumber 1. weight down, burden 2. to impede or hamper the function or activity of 3. to burden with a legal claim (as a mortgage)
Here's a non-exhaustive list:
- Technical inadequacies (functional)
- Technical inadequacies (maintainence)
- Poor documentation
- Lousy management structure
- Licensing troubles
- Copyright management trouble
To phrase the first four even more informally, that's "it doesn't work well", "the code inside it sucks", "i can't figure out how to use it", "the people working on it are jerks". They are technical or organizational and well outside the scope of what the FSF (and sister organizations FSFE, FSFI and FSFLA) are normally involved in. Comparisons between C# and other languages on the first three points (Objective-C has a defrobnicator and C# doesn't, nyah nyah nyah) miss the point. Project management is, I think, largely a personal choice and unless there are other indicators, I don't think you can say "community management is better than having a single entity". So contrasting Java's Sun^WOracle^WJCP management process with whatever C# / mono uses misses the point again, except where it touches on those other indicators.
But then we get to licensing, copyright consolidation and patents, and these are the relevant indicators for determining whether a platform or software program is encumbered (vs. Free). For licensing, the question to ask is "is this a Free Software license?". If you're cheeky, you could check the Open Source definition as well. Mono is under a mix of GPLv2, LGPLv2.0 (not 2.1!) and MIT/X11, so the code of Mono itself and its derived works is Free Software (by this measure) and works linked to the libraries are not encumbered.
Copyright management is one of those topics close to project management style, but I believe that a project with a clearly stated management style -- almost regardless of what that style is -- is better-off than one with a confused, ambiguous or stupid copyright management style (an example of the latter being: publish all the source with no attribution and no copyright headers). In any case, the Mono project with its mandatory copyright assignment (to Novell) is clear.
Which is when we come to the last item on the list, patents. Software patents per se do not exist in the EU, but they do in the US. Other parts of the world I am insufficiently aware of. There is the notion of the "submarine patent" (a term whose use has mutated over time, see this article for instance about long-pending patents). In current use, it seems to be a patent that is not-well-known, but applies to some piece of technology that is incorporated into a standard (either official through a standards organization or as a de facto standard). That's odd from a patent perspective, because the whole point of patent (dict: shown, open to public inspection, well-known) is to make sure that knowledge is pushed into the public domain at some point (that's the social contract around patents). In any case, Aaron phrases it quite well:
there is a rather higher than zero chance of Microsoft taking advantage of its patents and coming down on C# implementations when and if it feels like it. they have an agreement with Novell, and Novell thinks it covers everyone but Microsoft seems to disagree. and that's their public position.
however, we don't know for sure. so it's "only" a risk, not an absolute.
You will find similar statements about the risk entailed in using the possibly-patent-encumbered Mono .net framework in the comments to Andreas' blog entry (the first comment, by STiAX, in particular).
So the whole issue isn't about licensing, management or technical features, but purely about the risk involved with using a platform that is encumbered by patents. This is an issue on which the Free Software developer community has been either split or ambivalent for years. GIFs? MP3s? .NET apps? All encumbered at some point or in some way.
A similar kind of encumbrance would be if MIT (or Xorg) could retroactively re-license the X11 libraries to something proprietary (note: they cannot), thereby removing the platform upon which all Free Software X11 applications are built; it would be a risk, and given the importance of Free Software, a risk where the expected value of a manifestation is huge.
This isn't to say there's not other submarines in the water. We don't know. Maybe we should. The known submarine should be treated with caution. And the side of caution is to treat C# as a non-Free platform to be avoided.