The administration’s $800 billion stimulus program raised government demand for goods and services and was also intended to stimulate consumer demand. These interventions are usually described as Keynesian, but as John Maynard Keynes understood in his 1936 masterwork, “The General Theory of Employment, Interest and Money” (the first economics book I read), the main driver of business cycles is investment. As is typical, the main decline in G.D.P. during the recession showed up in the form of reduced investment by businesses and households.
What drives investment? Stable expectations of a sound economic environment, including the long-run path of tax rates, regulations and so on. And employment is akin to investment in that hiring decisions take into account the long-run economic climate.
The lesson is that effective incentives for investment and employment require permanence and transparency. Measures that are transient or uncertain will be ineffective.