You've got the question, or more accurately the burden of proof, the wrong way round. The patent people and their apologists want a superficially ridiculous monopoly on ideas (ie. on part of people's brains). They claim this causes more innovation to happen. They need to provide the evidence that this is true - not the other way around. Patents have existed for generations, if they truly were as useful as their proponents claim there would be so many studies demonstrating this that you wouldn't be asking a question. So, where are the studies? Where is the evidence? Same for copyright, where on earth is the evidence? I have certainly never seen any, in any field, for patents nor for copyright.