Capitalism and socialism opposed each other while mutually influencing the way each developed. If socialism has failed it is with respect to its declared objectives, namely to catch up and overtake the advanced capitalist countries through a progressive economic system. One of the main reasons for the failure of socialism lay in the inability of socialist States to adapt to change and in its systemic obstacles to innovation. While the historical judgement is that capitalism won, the outcome of the twentieth century is in fact ambivalent: considerable progress has been accompanied by the continuous lagging behind of the poor countries vis-à-vis the richer ones.