Many people working in the software industry seem to be coming to the conclusion that patents do more harm than good to their industry and therefore advocate abolishing software patents. The reasons they feel this way are pretty apparent. There are so many obvious¹ patents like the Eolas patent of Amazon’s one-click patent that any major piece of software is probably more likely to infringe on one than not. Something is pretty clearly wrong when people are spending more time worrying about accidentally infringing on someone’s patent than struggling with the problems the patented inventions solve. However, not all software patents are so unreasonable.

Consider google’s (well stanford’s) PageRank patent. Recognizing that one could create a useful measure of a page’s importance by summing up the importance of the pages linking to it and realizing that this could be efficiently computed using tricks from linear algebra was anything but trivial. Indeed, this kind of non-trivial application of mathematics to an ill-defined problem (return the best search) is a prototypical example of the sort of discovery that benefits from patent protection. Society can derive great benefits from these kinds of discoveries and money will lure people with the expertise to solve these problems away from pure mathematics or the sciences but without the ability to patent the discovery the financial incentives wouldn’t exist². While most software patents are more like the 1-click patent than the PageRank patent there is no shortage of real world problems that are crying out for a similarly brilliant solution.

In the face of examples like google’s PageRank patent it’s tempting to say that software patents are just dandy and the real problem is obvious patents. Unfortunately, it’s not that simple. Consider a hypothetical patent on the use of a LRU (least recently used) cache for texture data in a MMORPG client³. It’s certainly obvious in the sense that any decently skilled software developer would consider that solution if he was asked to solve the problem but until you actually try this design it’s not clear that an LRU cache would work. Maybe players don’t backtrack much so an LRU cache would simply waste resources on rooms the player won’t see again for awhile. At least in this example it seems clear that simply noticing that a fairly obvious approach solved the problem shouldn’t warrant a patent. The cost of actually testing out the ‘discovery’ is quite low and usually there are only a few obvious approaches to try.

However, such a rule would be totally unworkable in another industry where there might be a vast array of potential approaches that experts in the field would agree seemed promising but the cost of investigating them are quite high. For instance in the pharmaceutical industry everyone might realize that a certain large class of compounds are promising candidates to treat depression but actually evaluating each of these compounds for efficacy and safety is very costly. Incentivizing drug development requires that we let the pharmaceutical company patent their discovery that compound 5043A1 actually works to treat depression.

Ultimately I think the real problem stems from the fact that we are lumping two very different kinds of invention into the patent system. There is the first type of invention, like the google PageRank system, that represents a flash of inspiration to try something that no one else thought of and then there is the second type of invention that consists of the discovery that some potential solution really works. Ideally the patent system would protect the first kind of discovery pretty broadly but only protect the second sort of discovery in industries where it requires considerable resources to ascertain which of many potential solutions succeeds.