Advocates of open source often echo Google's "don't be evil" slogan, with non-FOSS code (among other things) being evil in this purview. That is, evil until you decide not to open source something you've created. Suddenly, you're the bad guy.

Case in point. A friend of mine is currently working on a software project with two components: a Web-based UI front end for driving the whole thing, and a back end which does the actual crunching. The back end is going to be FOSS; the front end is not. He asked me if this was "being evil" (my words, actually, not his), and I said, no. Just because you write a piece of software doesn't mean you're automatically obliged to FOSS it no matter what the circumstances.

How about front end/back end scenarios, like this one? Same thing. Quite a few of the companies who sell FOSS solutions make money by offering a closed-source front-end app, with the back end being entirely open. I asked them if they were worried about someone developing a competing front end, and the typical answer was: "It'll keep us on our toes." (Read: It's not an obstacle, it's an opportunity.)

I've written about all this before, but it's drawing ever more attention in the wake of licensing like the HPL, written specifically to prevent open source projects from being locked up as Web services. That's one scenario -- but what if you're the one doing the "locking-up", and you're doing it by simply never offering something open in the first place? Isn't that the right and the privilege of anyone who creates software?

I'd say so. And I would expect it's also the right and privilege of an open source advocate to recommend or even create an alternative. What they do not have the right to do, however, is morally decry someone for not offering a given item as open source. Barring extreme situations -- for instance, the bankruptcy of a company -- the choice to open source something should lie, first and last, with its creators. A parallel exists in the world of literature: just because someone writes something doesn't mean they're also obliged to publish it. That's typically the goal, but it isn't an inevitability.

That said, you don't have to wait long for one of the other big corollaries of the open source world to come up as a counter-argument.  If I use it (so goes the counter-argument), I should be able to take it apart / know how it works / build on it / etc. It's a tough argument to knock down; who wants to be seen as an enemy of understanding, or something of that ilk?

From what I see, the dividing line between having the right to keep your work to yourself and being evil is a question of who you're affecting with your actions and to what end. If you keep the core of your work open, that's what matters most. A proprietary front end or add-on may make it less useful to some people, but not uniformly worthless to everyone.

I don't pretend to think this ethical rule is universal, either. But it's a good place to start for anyone who finds themselves on what they feel to be the losing side of an argument about doing evil in the software world.