There is good data from Great Britain going back almost 200 years attesting to this. Interest rates are much higher than with commodity money. Commodity money facilitates real growth by investing savings, thereby causing increases in physical and intellectual capital. Fiat money results in nominal growth and less real growth. Eventually real growth and real earnings decrease.
Capital is destroyed and there tends to be less replenishment of physical and intellectual capital.
As productivity increases, prices tend to decrease, thereby resulting in more goods for more people at lower prices. This is what an increasing standard of living means. Prices tend to increase or, at best, remain stable. In all cases, inflation eventually results because the financial sector overreaches and because politicians inevitably become avaricious for additional funds. Commodity money is very savable because it doesn t obsolesce or deteriorate and is difficult to counterfeit.