>If not, what prevents or complicates the existence of such a quantity? I'm not an expert either but this type of thing is incredibly hard to measure not only

>If not, what prevents or complicates the existence of such a quantity? I'm not an expert either but this type of thing is incredibly hard to measure not only because of the constantly changing external forces from changing governments, technological progress, "animal spirits" etc., these things alone would make it nearly impossible, but there is also the role of money creation and very imperfectly run central banks around the world destabilizing things even much more. Think of it like trying to measure demand elasticity of bitcoins, it seems to be changing by the minute. Anyways, this whole discussion seems like a straw man to me. How can they pit keynesianism against neoclassicism and gloss over monetarism and the importance of money and central banks? Few serious economists will defend neoclassicism as a main causal factor of recessions at this point. Comparing descendant theories of Keynesianism with descendants of monetarism would be more appropriate.