1. The document discusses several economic theories of consumption, including the absolute income hypothesis proposed by Keynes which states that consumption is determined by current income. 2. It also covers Duesenberry's relative income hypothesis where consumption depends on income relative to others, as well as the life cycle hypothesis of Ando and Modigliani where consumption varies over one's lifetime based on earnings and savings. 3. Finally, it summarizes Milton Friedman's permanent income hypothesis which argues that consumption is based on estimated long-term future income rather than current or transitory income fluctuations.