Did Hayek have a monetary theory of business cycles?

Joseph Schumpeter, a careful reader of Hayek, categorized Hayek??s theory of economic cycles as non-monetary. Almost every other source, including Hayek himself, categorized the theory as monetary. The issue turns on the concept of causality being used. The question of what causality concept to apply to complex phenomena has substantive implications for economic theory. A simple concept of causality, appropriate to the study of some physical phenomena, will mislead when applied to complex phenomena. We provide examples of errors in analysis that follow from the wrong choice of a causal paradigm.