 Some post-Keynesians took a more progressive view than Keynes himself, with greater emphases on worker-friendly policies and redistribution.Robinson, Paul Davidson and Hyman Minsky emphasized the effects on the economy of practical differences between different types of investments, in contrast to Keynes' more abstract treatment.The theoretical foundation of post-Keynesian economics is the principle of effective demand, that demand matters in the long as well as the short run, so that a competitive market economy has no natural or automatic tendency towards full employment.