Beyond descriptive accuracy: The central dogma of molecular biology in scientific practice
Introduction
There is no denying the Central Dogma’s impact on the biological sciences. Indeed, this highly-influential principle in biology has been viewed as a catalyst for the Modern Synthesis in biology (Roll-Hansen, 2011), as definitive evidence against Lamarckian evolution (Camacho, 2020; Maynard; Cobb, 2017; Dawkins, 1982; Graur, 2019; Judson, 1979; Smith, 1993; Wilkins, 2002), and as evidence supporting the gene’s eye view of the development and evolution of an organism’s phenotype (Rosenberg, 2006; Weber, 2006). Some have even claimed that the Central Dogma can be justified using computational methods (Lin & Elowitz, 2016).
What’s more, since the Dogma’s formulation by Francis Crick in 1958, many commentators have debated the Dogma’s empirical adequacy (see e.g. Camacho, 2019; Crick, 1958 & 1970; Keyes, 1999; Stotz, 2006; Rosenberg, 2006; Weber, 2006; Griffiths & Stotz, 2013; Griffiths, 2017; Sustar, 2007). In these debates, however, fairly little attention has been paid to the Dogma’s practical significance to biology. This is somewhat surprising since there are numerous ways in which a scientific principle may be of use to science even if it fails to be empirically adequate or descriptively accurate.
A false scientific principle may be of use to science as an idealization (McMullin, 1985). Beyond being an idealization, a scientific principle may also engender an understanding of nature: as Morrison (2015) has argued, empirically inaccurate mathematical models—such as the Hardy-Weinberg Law in Population Genetics—afford a better understanding of the “genetical basis of evolutionary change” than more empirically-accurate models (Morrison, 2015, p. 33). Nancy Cartwright (1983) has also noted that certain laws—though false descriptions of what really happens—aid in the construction of highly predictive models. Additionally, Jonathan Birch (2014) has pointed out that scientific principles, such as Hamilton’s Rule in sociobiology, may posit a set of general features that help unify seemingly disparate phenomena under a single conceptual scheme. All of these examples point to the possibility that the Central Dogma may be plausible on practical grounds alone even if it fails to be descriptively accurate.
My aim in this paper is to move beyond discussions of descriptive accuracy, and instead to evaluate the Central Dogma’s significance to biology from a purely practical perspective. It is important to note from the get-go, though, that this paper focuses on the Dogma’s contemporary significance to biological practice. The Dogma’s historical development will be left open for a future occasion. To do this, I consider four distinct approaches for determining the non-descriptive methodological and practical significance of a scientific principle (McMullin, 1985; Cartwright, 1983; Elgin, 2014; Kitcher, 1989), and determine whether the Dogma is made plausible by any of these approaches. In doing this, my hope is to consider the Central Dogma in an entirely new light.
This paper is organized as follows. After demonstrating that the Central Dogma admits of many interpretations (in Section 2), I settle on Francis Crick’s original formulation of the principle (1958), which holds that information cannot flow from proteins to proteins, or from proteins to nucleotides.1 In Section 3, I consider the approaches of Ernan McMullin (1985), Nancy Cartwright (1983), Philip Kitcher (1989), and Catherine Elgin (2016; 2009; 2004), and evaluate (in Section 4) whether the Dogma is useful as an idealization in science, as a predictive tool, as a unification principle, or as a principle that affords understanding of nature. These approaches, I argue, fail to vindicate the Central Dogma. I conclude that the Dogma is not significant to contemporary biological practice.
Section snippets
Crick’s central dogma of molecular biology
When Francis Crick first introduced the Central Dogma in 1958, his aim was to capture the molecular interactions underlying protein synthesis (Crick, 1958, 1970). For Crick, the Central Dogma posits a fundamental process involving the transfer of information between three distinct bio-molecules: DNA, RNA and protein. Crick’s insight, roughly, was that once information passed from DNA to RNA to protein, it did not get out again. That is, once DNA segments were transcribed into segments of RNA,
The central dogma from a practical perspective
Now that we’ve made explicit how the Central Dogma is to be understood in this paper, we can go on to ask whether the Central Dogma is useful to the biological sciences, independently of its empirical adequacy. As noted previously, many commentators have debated the Central Dogma’s descriptive accuracy (see e.g. Camacho, 2019; Crick, 1958 & 1970; Keyes, 1999; Stotz, 2006; Rosenberg, 2006; Weber, 2006; Griffiths & Stotz, 2013; Griffiths, 2017; Sustar, 2007). The aim in this paper, however, is to
Conclusion
It’s worth taking a moment to make the scope of my argument explicit. I argue in this paper that if the Central Dogma is to be understood as an idealization, a unifying principle, or a predictive principle, then it is not significant to biological practice. This is because, under such approaches, the Dogma amounts to a triviality. Of course, these considerations do not imply that the Dogma may not be significant to science if understood in some other way; however, at this point, it is not yet
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