Steve Fazzari of Washington University in St. Louis talks with EconTalk host Russ Roberts about the economics of Keynesian stimulus. They discuss the stimulus package passed in February 2009 and whether it improved the economy and created jobs. How should claims about its impact be evaluated? What can we know as economists about causal relationships in a complex world? The conversation includes a discussion of the underlying logic of Keynesian stimulus and the effect of the financial crisis on economic research and teaching.