Starting with a macro-economic model based upon the NAIRU (the nonaccelerating inflation rate of unemployment), we show that, in a world with no (speculative) financial transactions, the macro- economy shows a stable equilibrium state. Including income from (speculative) financial transactions will lead to instability if the amount is sufficiently large. Considering the present amount of financial transactions, stability is impossible. Therefore, further financial crashes are not only likely but inevitable.Starting with a macro-economic model based upon the NAIRU (the nonaccelerating inflation rate of unemployment), we show that, in a world with no (speculative) financial transactions, the macro- economy shows a stable equilibrium state. In...