 Ron Mallon and Jonathan Weinberg (2006, 2008) argue that an innate phenotype is “properly understood” (2008, 415) as one that is invariant in normal environments (Section 3.2), but also produced by a ‘closed developmental process.’ Mallon and Weinberg’s distinction between ‘open’ and ‘closed’ processes appears to be the same as that that drawn by Ernst Mayr (1961) between open and closed genetic programs. An open developmental process can respond to different environments by producing a range of different phenotypes, while a closed developmental process can only produce one or a small number of outcomes and changing the environment either has no effect or simply terminates the process, perhaps killing or severely impairing the organism.