I personally do not believe that either patents or copyright are incentives for innovation. Partly this is because innovation existed long before patents and copyright. Mainly it is because resources spent on patents is resources not spent on innovation. Patents and copyrights show themselves only at the end of the innovation which they claim to protect, which is how much of a head start that company has on the competition. When competitors merely copy instead of working their own innovations, they do not have the same solid background of understanding and cannot use the copied knowledge to leapfrog the originator. Further, the harder the research that produced the patent, the more important the patent, so we are told, but this also means that copying is that much harder too, thus making the patent less worthwhile.
I said "mainly" for that second reason, but that's not true. Mainly I despise patents and copyrights because the boundaries are so vague as to open up all the abuse we have seen. Steve Jobs took it as a personal affront that Google would dare challenge the iPhone, and Apple now doesn't seem inclined to stop the systemic abuse he started. They are not the first, of course. Any gain to society due to patents is surely far outweighed by all these crazy lawsuits. Oracle and the phone wars are just the latest manifestation. Copyrights are no better, not only because it's impossible to be definitive as to the difference between fair use and plagiarism, "inspired by", "based on", and so on. But worse is that music especially has always been inspired by other music. To think it proper to lock up music for 75 years after the writer dies is just bizarre.
Copyrights especially offend me for the idea that someone can write a song and lock up royalties for 75 years after he dies. It's an interesting income-redistribution scheme, but it's hardly beneficial to anyone, especially not society.