MIT professor Jonathan Gruber lectures on the fundamentals of tax theory in this session from 14.41, Public Finance and Public Policy, at MIT. He lays out how economists define the tax base and walks through the concept of tax incidence, the question of who actually bears the economic burden of a tax regardless of who writes the check to the government. The lecture works through the difference between statutory and economic incidence, showing how the split between consumers and producers depends on the elasticities of supply and demand rather than on legislative intent. Gruber uses supply and demand diagrams to demonstrate how taxes shift equilibrium prices and quantities, and connects the analysis to real policy questions about who ends up paying for taxes on goods, labor, and capital. Runtime is 78 minutes, part of the fall 2024 MIT OpenCourseWare series.