Complex sentence: In particular, Pigou is responsible for the famous distinction between private and social marginal products and costs and the idea that governments can, via a mixture of taxes and subsidies, correct such market failures--or "internalize the externalities".
Split into simpler sentences: In particular, Pigou is responsible for the distinction between private and social marginal products and costs. He originated the idea that governments can, via a mixture of taxes and subsidies, correct such market failures--or "internalize the externalities".