Some unsolved problems in economics include: * What is the proper size and scope of government? Where can government intervention improve on the market? Does a market failure necessarily mean that government intervention is warranted? Can intervention make things worse? If the government intervenes in a market, how should it intervene? To what extent is public ownership of assets and businesses warranted? * The Great Depression. What truly caused the Great Depression? Did one single event cause it? Was the United States the cause? What set the stage for it? See also: possible Causes of the Great Depression * The Equity premium puzzle. Can we explain the Equity Premium Puzzle? Why is it that observed average annual returns on stocks over the past century are higher, by approximate