Empirical lognormality of biological variation: implications for the ‘zero-force evolutionary law’

ABSTRACTThe zero-force evolutionary law (ZFEL) of McShea et al. states that independently evolving entities, with no forces or constraints acting on them, will tend to accumulate differences and therefore diverge from each other. McShea et al. quantified the law by assuming normality on an additive arithmetic scale and reflecting negative differences as absolute values, systematically augmenting perceived divergence. The appropriate analytical framework is not additive but proportional, where logarithmic transformation is required to achieve normality. Logarithms and logarithmic differences can be negative but the proportions they represent cannot be negative. Reformulation of ZFEL in a proportional or geometric reference frame indicates that when entities evolve randomly and independently, differences smaller than any initial difference are balanced by differences larger than the initial difference. Total variance increases with each step of a random walk, but there is no statistical expectation of divergence between random-walk lineages.

El estatus metateórico de ZFEL

In a recent book, McShea and Brandon argue that the observed diversity and complexity of life are explainable by a principle they call the “zero-force evolutionary law” or “ZFEL”. Although this principle would be implicit in many explanations given by biologists, it would have never been made explicit. Assuming that this idea is interesting, and that the authors are right, we will discuss the metatheoretical way in which they present said principle, as being a part of probability theory. This allows the authors to claim that probability theory provides the reductive basis for all evolutionary biology (given that they consider other principles, such as the principle of natural selection, as part of probability theory as well). We will defend, in accordance with them, that ZFEL is not a solely biological principle, but not because it is a part of probability theory, but rather because it is a specific version of the principle of common cause.

Toward a virtue account of science

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] This dissertation argues for a virtue account of science in which foundational scientific goals are achieved by scientists' employment of virtuous tools and practices. Chapter 1 discusses contemporary literature on the nature and success of biology, especially the realism/antirealism debate within biology. This chapter also provides background into the debate surrounding explanation and understanding. Chapter 2 challenges the idea that successful biology requires appeals to laws of nature by arguing that some foundational scientific goals best realized by unlawful tools and practices. This result provides a criterion for determining whether a discipline is more scientific than another another; disciplines are more or less scientific to the extent that they are able to achieve foundational scientific goals. Chapter 3 examines a test case for the result in Chapter 2 by analyzing McShea and Brandon's [2010] Zero Force Evolutionary Law (ZFEL). I show that the ZFEL's failure as a law does not impact its usefulness to scientists, who are able to use the ZFEL to achieve a number of important, foundational goals. Chapter 4 provides a strategy for determining foundational scientific goals by examining the debate surrounding the relationship between understanding and explanation. By analyzing Khalifa's [2013a] Explanatory Knowledge Model of Understanding, I demonstrate that understanding is not a species of explanation and is thus a foundational scientific goal. It is a goal that scientists aim at, has intrinsic benefit, and is not reducible to other scientific goals. Finally, Chapter 5 presents an outline of the virtue account. On this account, science is successful to the extent it regularly achieves foundational scientific goals. Science does so by employing virtuous tools and practices--those tools and practices that regularly allow for the achievement of foundational goals. The chapter concludes by examining several benefits of this view and considering future avenues for research.