...anyone who finds Paul Krugman (and his followers on your Facebook friend feed) ridiculous, partisan, and hypocritical. I'm sure he's a nice guy and such; he has a cat that appears well-fed.
Murphy lays out recent statements from Paul Krugman and Christina Romer where they state that there is no evidence that lower or higher marginal tax rates and corporate tax rates have a positive/negative impact on GDP growth. Murphy then cites a great deal of evidence, including from Krugman and Romer, in which it is concluded that taxes matter. That is, lower marginal tax rates and lower corporate tax rates will raise GDP growth while higher marginal tax rates and higher corporate tax rates will lower it.
So, when you and your friends are discussing fiscal stimulus and its merits, be sure to have read the following article.
Robert P. Murphy, What Economic Research Says About Fiscal Austerity and Higher Tax Rates | Library of Economics and Liberty