|Into the ongoing debate, 'The GPL versus the BSD license', I'd like add yet another opinion. I agree with the positive points claimed by both sides, but I don't generally agree with the negative ones directed at the opposition. That is, I think that both licenses have strong points that the other lacks, and further, that the two actually complement each other when both are applied to products in the same market. We need them both.|
In the operating systems arena, for example, I believe that Linux and *BSD together will eventually cover more ground than either could cover independently. Companies that might be uncomfortable building products based on GPL'd code can use a BSD-derived package and enter the market quicker and cheaper than if they built their product from the ground up. Further, a company that initially develops a closed source product -- but based on BSD-licensed source -- is more likely to release the source in the future, as their situation changes, than a company that develops a purely proprietary product.
Meanwhile, individuals who aren't striving for an exclusive marketing advantage in their package can spread the open source approach with more certainty by using the GPL.
Another advantage of having more than one major strain of open source license is purely psychological; the presence of multiple open source licenses makes each of them seem more mainstream and, therefore, less radical. This makes it feel like a smaller, safer step for a company to try out open source.
The license to choose, of course, depends on your goals. The BSDL is less restrictive and is, therefore, more free. The GPL, while less free, guarantees that published derivitive works retain the original set of freedoms (and restrictions). Therefore, if you want maximum freedom for the licensee, the BSDL is best. If you want guaranteed access to the source of future published code, the GPL is best. In practice, each allows the creation of open source code that the other would not. If I had to assign the common labels to them, I'd say that the BSDL is more consistent with the term 'free software' and that the GPL is more aggressively 'open source'.
That is, the GPL provides for the distribution of multiple generations of source code. The BSD license encourages more people in wider ranging situations to try out, and maybe release, source code, but still allows for new variants to become closed in the future.
While the two licenses do have an overlapping market, together they encompass a larger potential user base. As long as people and businesses come in countless varieties, no single license will fit them all. That the open source/free software world is large enough to require multiple, and quite different, licenses, also seems to me to be a good thing.