Abstract
In this paper we chart epistemological similarities between shared function talk in biology and the engineering sciences, focusing on the notions of biological advantage function and technical advantage function. We start by showing that biological advantage function ascriptions are common in biology and that technical advantage function ascriptions are common in engineering science. We then proceed to show that these ascriptions have a very similar structure and that their epistemic value also is similar: both biological advantage function and technical advantage function ascriptions provide the means to answer what-would-happen-if questions. We develop and illustrate our claims with four case studies: two from biology, and two from engineering design research. Our results offer new insights into a relatively neglected issue in both philosophy of biology and technology, viz. assessing the explanatory and predictive utility of function ascriptions.