Where capitalism has shortfalls socialism attempts to fill the gap.
From Paul Krugman, Nobel Prize winning economist, columnist for the New York Times, former professor of economics at MIT, professor emeritus at Princeton, Centennial Professor at London School of Economics, (MIT, Princeton, and LSE being three of the top schools of economics in the world), who says that he is a liberal and what would be called a "social democrat" in Europe:
"But who can now use the words of socialism with a straight face? As a member of the baby boomer generation, I can remember when the idea of revolution, of brave men pushing history forward, had a certain glamour. Now it is a sick joke: after all the purges and gulags, Russia was as backward and corrupt as ever; after all the Great Leaps and Cultural Revolutions, China decided that making money is the highest good. There are still radical leftists out there, who stubbornly claim that true socialism has not yet been tried; and there are still moderate leftists, who claim with more justification that one can reject Marxist-Leninism without necessarily becoming a disciple of Milton Friedman. But the truth is that the heart has gone out of the opposition to capitalism."
"[Speaking of countries climbing their way out of abject poverty.] And once again, capitalism could with considerable justification claim the credit. Socialists had long promised development; there was a time when the Third World looked to Stalin’s five-year plans as the very image of how a backward nation should push itself into the twentieth century. And even after the Soviet Union had lost its aura of progressiveness, many intellectuals believed that only by cutting themselves off from competition with more advanced economies could poor nations hope to break out of their trap. By the 1990s, however, there were role models showing that rapid development was possible after all—and it had been accomplished not through proud socialist isolation but precisely by becoming as integrated as possible with global capitalism."
-- Krugman, Paul. The Return of Depression Economics and the Crisis of 2008
