“Some economic phenomena can result from a variety of causes. A temporary increase in unemployment, for example, might be caused by a sudden, disruptive change in production technology, or in trade patterns, or in labor or tax laws; or it could be caused by natural disasters or wars, or by recessions due to monetary or fiscal policy. In such cases the exact cause is unclear.
By contrast, a few economic phenomena have one and only one root origin; when we see the effect, we can be sure of the cause. One of these is inflation. Its root cause is a settled matter for most economists. In the words of the great Milton Friedman, whose masterwork with Anna Schwartz, A Monetary History of the United States, did a lot to settle the matter, ‘Inflation is always and everywhere a monetary phenomenon.’” Read more.