Nos comentários ao seu post Re: Acumulação de moeda e reservas fraccionárias, o CN escreve "Na verdade, o sistema funciona com coeficiente zero, porque os bancos expandem os depósitos e quanto é necessário o banco central injecta mais reservas ou vice-versa, existindo confusão entre moeda adicional para suportar as trocas e moeda adicional para dar crédito adicional."
Consider, for example, the "paradox of thrift." Suppose that for some reason the savings rate--the fraction of income not spent--goes up. According to the early Keynesian models, this will actually lead to a decline in total savings and investment. Why? Because higher desired savings will lead to an economic slump, which will reduce income and also reduce investment demand; since in the end savings and investment are always equal, the total volume of savings must actually fall!
Or consider the "widow's cruse" theory of wages and employment (named after an old folk tale). You might think that raising wages would reduce the demand for labor; but some early Keynesians argued that redistributing income from profits to wages would raise consumption demand, because workers save less than capitalists (actually they don't, but that's another story), and therefore increase output and employment.
Such paradoxes are still fun to contemplate; they still appear in some freshman textbooks. Nonetheless, few economists take them seriously these days. There are a number of reasons, but the most important can be stated in two words: Alan Greenspan.
After all, the simple Keynesian story is one in which interest rates are independent of the level of employment and output. But in reality the Federal Reserve Board actively manages interest rates, pushing them down when it thinks employment is too low and raising them when it thinks the economy is overheating. (…)
But putting Greenspan (or his successor) into the picture restores much of the classical vision of the macroeconomy. Instead of an invisible hand pushing the economy toward full employment in some unspecified long run, we have the visible hand of the Fed pushing us toward its estimate of the noninflationary unemployment rate over the course of two or three years. To accomplish this, the board must raise or lower interest rates to bring savings and investment at that target unemployment rate in line with each other (…).
To me, at least, the idea that changes in demand will normally be offset by Fed policy--so that they will, on average, have no effect on employment--seems both simple and entirely reasonable.