Going "downstream", from the technology to the sale of goods, market signals enter the picture at opposite stages. First, market signals can act "ex ante" in the competition among different paradigms: if more paradigms are available, firms would select one or the other according to their expected profitability. But once a paradigm is affirmed, the direction of technological change would be already implied by its technological prescriptions. Second, market signals can act by selecting "ex post" those applications of the affirmed paradigm (i.e. the final products) that best fit the market requests. However, at that point their impact on the direction of technical change would be null, since such direction had already been decided by the prescriptions of the affirmed paradigm.