Even for that evidence would seem to be required. Patents should indeed act as an incentive to invest in an invention. But how many potential investments in in

Even for that evidence would seem to be required. Patents should indeed act as an incentive to invest in an invention. But how many potential investments in inventions are dissuaded by the countervailing thought that someone must already have a patent on it? ... by the thought that getting a patent is too complicated? ... or too expensive? ... or that the invention is likely to lead to patent litigation?