Whatever you think of former Fed chair Alan Greenspan, he is one of the few public voices identifying runaway entitlement costs as a structural threat to the economy and nation. We can summarize Greenspan's comments very succinctly: there is no free lunch. The more money that is siphoned off for entitlements, the less there is for investment needed to maintain productivity gains that are the foundation of future income generation: Greenspan: Worried About Inflation, Says “Entitlements Crowding Out Investment, Productivity is Dead” (via Mish)