maskin suggested that software patents inhibit innovation rather than stimulate progress. software, semiconductor, and computer industries have been innovative despite historically weak patent protection, he argued. innovation in those industries has been sequential and complementary, so competition can increase firms' future profits. in such a dynamic industry, "patent protection may reduce overall innovation and social welfare". a natural experiment occurred in the 1980s when patent protection was extended to software", wrote maskin with co-author james bessen. "standard arguments would predict that r&d intensity and productivity should have increased among patenting firms. consistent with our model, however, these increases did not occur". other evidence supporting this model includes a distinctive pattern of cross-licensing and a positive relationship between rates of innovation and firm entry.