He lists a lot of good reasons to be against software patents, but here’s his favorite:
I am against software patents because it is not reasonable to expect that the current patent system, nor even one designed to improve or replace it, will ever be able to accurately determine what might be considered legitimately patentable from the overwhelming volume of innovations in software. Even the most trivial of software applications involves hundreds, potentially thousands of design decisions which might be considered by those aggressively seeking patents as potentially protectable inventions. If even the most basic elements of these are patentable, as they are currently, the patent system will be fundamentally unable to scale to meet that demand. As it is today.
The argument that designing a functional patent system for software is infeasible is interesting and correct.
Here’s another reason he doesn’t list that I think should give patent advocates pause. If you look at all of the software being written, is there any evidence that companies and projects that apply for patents are creating any more value than the companies and projects that aren’t? And if they are not, what is the point of the patent system?