There was a time when the models and mathematics of neoliberal economists (who are not really economists in the first place) could not be contested. When they said such and such a number or curve was telling us the truth, it was accepted as nothing but the truth. But because we are now stuck in the post-neoliberal world (a world we entered in 2008), we can finally challenge the findings of neoclassical economists without fear of losing our jobs. An example: A paper by two economists (Carmen Reinhart, now a professor at Harvard Kennedy School, and Kenneth Rogoff, an economist at Harvard University) who came up with some number (90%) that showed such and such a thing was true (government debt at this point slows growth) has been debunked only two years after it was published. The Economist:

The new paper, by Thomas Herndon, Michael Ash and Robert Pollin of the University of Massachusetts, Amherst, sought to replicate the Reinhart-Rogoff result for the post-war period. They reckon that mistakes in the analysis led Ms Reinhart and Mr Rogoff to understate average growth at high debt levels...Taken together, the authors of the new paper reckon that average post-war growth above the 90% threshold ought to have been reported at 2.2% rather than -0.1%.