Tyler Cowen's anti-Keynesian manifesto has been ably discussed by Professor Simon Wren-Lewis at Mainly Macro. I thought what merited additional attention is Professor Cowen's first assertion:

1. Keynesians predicted disaster following the American fiscal sequester, and the pace of the recovery accelerated.

I don't think of myself as a Keynesian (the material I teach in my courses are what have been termed the (old) neoclassical synthesis, i.e., Keynesian short run plus Classical long run — and some New Keynesian), but I thought it useful to take a look at what I wrote about the impact of the sequester. On February 19, 2013, I wrote, citing a Macroeconomic Advisers assessment, the following:

…we now put the odds of a sequestration at close to 50%, and rising.

• Our baseline forecast, which shows GDP growth of 2.6% in 2013 and 3.3% in 2014, does not include the sequestration.
• The sequestration would reduce our forecast of growth during 2013 by 0.6 percentage point (to 2.0%) but then, assuming investors expect the Federal Open Market Committee (FOMC) to delay raising the federal funds rate, boost growth by 0.1 percentage point (to 3.4%) in 2014.
• By the end of 2014, the sequestration would cost roughly 700,000 jobs (including reductions in armed forces), pushing the civilian unemployment rate up ¼ percentage point, to 7.4%. The higher unemployment would linger for several years.

 The macroeconomic impact of the sequestration is not catastrophic. Nevertheless, the indiscriminate fiscal restraint would come on the heels of tax increases in the first quarter that total nearly $200 billion, with the economy still struggling to overcome the legacy of the Great Recession, and when the FOMC is constrained in its ability to offset the additional fiscal drag with a more accommodative monetary policy. …

 Here is a graphical depiction of Macro Advisers' estimates of the impact of the sequester.

Source: Macroeconomic Advisers (2/20/2013).