Blair writes: > I thought the whole point was that "downward-sloping demand [or any other] > curves" require the ceteris paribus assumption, so that things hold still > long enough for us to draw a curve. In the real world time passes and > nothing is constant/stays the same, and therefore it's impossible to draw a > curve. In other words, ceteris paribus is useful to show theoretical > relationships, that is, the way our different concepts are related to each > other logically in our [sic] theory, but any analysis that requires a > ceteris paribus assumption, specifically any neoclassical graphical model > or its algebraic equivalent, is useless for attempting to understanding how > real world dynamics will develop. I'm pretty ignorant about P-K material, > but I thought this was the fundamental point of Keynes thinking about > uncertainty (that none of the curves stay still long enough to get a good > look at them, so to speak), and Joan Robinson's "logical time." Putting aside possible complications introduced by interaction effects and macroeconomic externalities (which is what I understand Keynes to have been talking about), ceteris paribus claims are still relevant in a changing world. For instance, even if the demand curve shifts around, realized quantity demanded may still be lower than what it otherwise would have been had the indicated parameter (e.g. the level of the minimum wage rate) not been altered. Gil Skillman
