  Although both Rosenberg and Weber reject the idea that biologists' explanation of the intitial stage of pattern formation makes essential reference to the idea that genes or DNA have intentional information, they assume that the explanation makes essential reference or implies the existence of a genetic program. But it is unclear why the use of the term program is any less metaphorical than the term positional information. Rosenberg argues that we can infer that DNA can execute programs from the fact that computers can be built out of DNA and these DNA-based computers can execute programs in the same sense that silicon-chip-based computers can execute programs. Nevertheless, it is unclear what adding the phrase "executing a genetic program" adds to the explanation of intial pattern formation. Weber and Rosenberg present their summaries of the explanation in causal terms such as ‘generate’, ‘deposit’, ‘activate’, and ‘deactive’. One might ask whether the causal explanation supersedes the metaphorical idea that DNA programs development.