Post-Keynesians are economists who build on the ideas of John Maynard Keynes, emphasizing the importance of demand in driving economic growth and employment. They argue that markets are not always efficient and can be influenced by uncertainty, leading to fluctuations in economic activity. This school of thought critiques mainstream economics for relying too heavily on mathematical models and assumptions of rational behavior. Post-Keynesians advocate for policies that address income inequality and promote full employment, often supporting government intervention in the economy to stabilize it during downturns.