Read each of the three linked articles.

http://www.economist.com/blogs/freeexchange/2010/07/fiscal_policy

http://www.thefiscaltimes.com/Columns/2014/09/02/Objections-Fiscal-Policy-are-Groundless-It-Works

http://www.wsj.com/articles/SB10001424053111903596904576514552877388610