This paper shows the robust non existence of competitive equilibria even in a simple three period representative agent economy with dynamically inconsistent preferences. We distinguish between a sophisticated and naive representative agent. Even when underlying preferences are monotone and convex, we show by example that the induced preferences, at given prices, of the sophisticated representative agent over choices in first period markets are both non convex and satiated. Therefore, even allowing for negative prices, the market clearing allocation is not contained in the convex hull of demand. Finally, with a naive representative agent, we show that perfect foresight is incompatible with market clearing and individual optimization at given prices
