Two great modern classical liberals, Friedrich von Hayek and Milton Friedman were very influential economists. Their works on economic method and methodology are worth particular attention. Despite similarities in their ideology, their views in the field of philosophy of science were poles apart, although at the same time they both considered themselves to be followers of Popper. This paper attempts to resolve the issue of who might be closer to this philosopher. The first section introduces the main task. The second section briefly describes Popper's idea of falsification. The third section summarizes Friedman's famous essay on method. The fourth section presents Hayek's approach as opposed to it. The fifth section offers concluding comments.