This session examines what evolutionists mean by 'design': first, by examining the structure of functional explanations, and then by analyzing the role of reverse engineering in interpreting adaptation.

Arno Wouters, Nijmegen University
"Design Explanation"

As is well known, functional biologists often explain the structure of the organs and behaviours of the organisms in which they are interested by appealing to the role of those organs and behaviours in the maintenance of the organism and the fitness advantages of that structure over other possible structures. Such explanations are usually called 'functional explanations' by the biologists who propose them. I shall call them 'design explanations' to avoid confusion with other uses of the term functional explanation. In this paper I address the question how such explanations are explanatory. My main claim will be that despite the fact that design explanations are not of a causal nature, they are explanatory because they reveal the structure of the living world.

Robert Richardson, University of Cincinnati
"Reverse Engineering and Design"

Reverse engineering, the study of design, is often taken as important for the understanding of adaptation, including work in evolutionary ecology and evolutionary biology as well as evolutionary psychology. There are a number of forms which reverse engineering can take, with varying purposes. In one form, information concerning constraints is incorporated into evolutionary models as constraints on the available range of biological form, specified prior to the assessment of adaptation. The alternative is to develop design constraints a posteriori, using the performance of the phenotype to determine the environmental factors that shaped that design. I focus on the first use of reverse engineering and, in particular, its importance in understanding adaptation.

Derek Turner, Connecticut College
"The Role of Analogy in Reverse Engineering"

This paper begins by distinguishing two reverse engineering problems: the generation and testing of architectural hypotheses and the generation and testing of adaptationist hypotheses. On the basis of two examples from vertebrate paleontology, I show that reverse engineering often involves three steps: (1) analogical hypothesis formation; (2) Comparative judgments about goodness of design; and (3) Popperian falsification. I argue that the importance of the first step has been underappreciated, and indeed that the ready availability of observable analogues (whether living organisms or human artifacts) is what makes reverse engineering problems tractable.