French competition clusters rely on the principle that relationships between innovation actors stimulate the knowledge diffusion, accessibility, and appropriation that are necessary in order to innovate. Considering the innovation process which has its roots in the design process, this paper shows that if knowledge diffusion is a necessary condition for innovation, it is not sufficient. Creative rationality implies knowledge combination, without which innovation cannot occur. Knowledge production is thus a condition for innovation. In turn, the paper questions the importance given to knowledge diffusion in the academic literature. It also shows that the issue of knowledge production is underestimated in the French competitiveness cluster framework and that some action levers may also remained hidden. JEL codes: D83, O3, R10, R58