In this article we demonstrate that and why Aristotle's four causes are essential for a scientific articulation of designerly knowledge. We show that properly understood, Aristotle's notion of a cause, including the final cause, is not in conflict with modern science. Rather, when it comes to understanding living beings as such, all of the four Aristotelian causes are still crucial. We argue that this implies that design research, too, must appeal to the four causes, because artifacts must be understood in terms of the role they play in the life of living beings.