 Economist Milton Friedman was critical of Hayek's writings of the 1970s on monetary reform.Noting Hayek's vigorous defense of "invisible hand" evolution that Hayek claimed has created better economic institutions than could be created by rational design, Friedman pointed out the irony that Hayek was then proposing to replace the monetary system thus created with a deliberate construct of his own design.Moreover, Friedman noted, there is nothing in the current law of most developed economies to prevent voluntary bilateral exchange via any medium freely accepted by two parties.