At FOSDEM 2014, Eileen Evans gave a talk entitled “Licensing Models and Building an Open Source Community“. The talk is basically a discussion how Evans changed her mind about the suitability of permissive licenses in vibrant open source communities. She proposes that a vibrant community requires excellent technology, suitable governance, and a license that the community perceives as fair.
A decade ago, Evans was working at Sun and considering what license to use for OpenSolaris. The decision at the time was that because copyleft licenses require downstream changes to be returned to the community (in the sense that they remain freely-licensed), copyleft licenses are necessary for a healthy community.
In the intervening years, many projects have adopted permissive licenses. The GPL family is no longer the majority license, according to several surveys. Vendor participating in open source projects favored strong copyleft until around 2006, but the preference has shifted toward permissive licenses. A survey of GitHub projects showed the MIT license with a dramatic lead over the next-most-widely-used license.
Based on this, Evans concluded that permissive licenses can, in fact, be used
Is that still true today? Projects are increasingly using permissive licenses. MIT dominates GitHub. Vendor engagement (participation in projects) was toward strong copyleft until ~2006 when permissive licenses take over. 5x increased in contributors to CloudStack after changing from copyleft to permissive. Permissive licenses may be used to build a community.
Of course, there are few who would take the position these days that permissive licenses can’t be used. Even noted copyleft advocate Bradley Kuhn can be heard agreeing on the video, though he points out his view that copyleft licenses make for better communities. Perhaps the question should be phrased as “what kind of communities develop?”
In conducting research for my thesis, I came across a study that showed copyleft licenses were associated with higher user engagement, but permissive licenses were associated with higher developer engagement. This makes sense, since not all developers develop FLOSS. A developer who isn’t developing FLOSS would probably be more drawn to a project where the license was conducive to proprietary downstreams.
Evans’ anecdote about the increase in contributions to CloudStack when it switched from copyleft to permissive licensing may or may not tell us something. It may be purely coincidental. An increase in the popularity of the project or of cloud computing generally may have driven the change. And of course, there’s more to a community than the number of committers.
I suspect that the license itself may be less important than the overall governance model. It’s certainly an area that merits further research.