 The interrelated issues concerning pragmatism, scientific realism, and abstraction become even more pertinent when the theory and models that inform experiments, such as the genotype-phenotype distinction in Mendelian research, are extended to less-controlled situations, such as agricultural breeding trials, and to analysis of data derived from them. As noted earlier, quantitative genetics relies on models of contributions from unobserved, theoretical genotypes. Analyses of data using those models allow breeders to decide which traits to enhance through selection even though they have no evidence independent of the data to confirm the assumption in their models about theoretical genotypes and their contributions (Lloyd 1988). Yet, as publications, careers, release of varieties, software packages, and so on get built on such a foundation, it becomes ever more difficult in practical terms for researchers to promote alternatives that do not rest on the unobserved and unconfirmed entities and properties. Indeed, unconceived alternatives, the possibility that Stanford (2006) highlights, may well include theories that entail methods that are, for various reasons, impractical. The pragmatic issue of needing a practical method applies in turn to philosophy: When philosophers make distinctions or otherwise point to issues that scientists have left unclear or under-examined, by what means do they envisage influencing the scientists to change their views or practices? That question is left open by this entry. The genotype-phenotype distinction has been positioned in this entry in relation to control of biological materials and conditions, thus drawing attention to the challenge of reintegrating what had been de-emphasized through that control. Yet, no method is provided for philosophers to get the challenge taken up beyond the implication that the description—the framing—would be a helpful starting point. In other words, the entry has positioned the genotype-phenotype distinction in line with the descriptive emphasis in the New Experimentalism on scientific practice, a prescriptive possibility of reintegration, and an open question about the method needed to shift actual practice. (The contrast of descriptive versus prescriptive perspectives is explored in Stegenga’s 2009 review of Weber’s contribution to philosophy of experimental biology.)