What Are the Biological Sciences (Not)?
The biological sciences are as diverse as the physical sciences in the kinds of systems they study, in the methods employed, in their standards of evidence, and in what counts as explanations of their phenomena.
For example, the daily work and theoretical contexts of molecular genetics are very different from those of comparative morphology or developmental biology. One reason we present a set of sketches of particular topics in the sections that follow is that it is very difficult to say anything that is both substantive and accurate about all of biology.While it is difficult to characterize all of biology in a meaningful way, it is easy to point to widespread misconceptions among researchers in the humanities about what biology is and what biologists do. These misconceptions have several sources, one of the most important of which is the kinds of biology that are standardly taught in American high schools. Because of the emphasis on cell biology on the one hand and on Mendelian and molecular genetics on the other, one who does not study biology at the university level could be forgiven for concluding that the biological sciences are neither as quantitative nor as richly theoretical as the physical sciences, and therefore that there is no interesting work for philosophers of science to do. As the discussions of phylogenetic inference (§3), evolution and population growth (§4), and kin and group selection (§5) below show, this notion is mistaken.
The evolutionary synthesis that brought together nineteenth-century thinking about phenotypic variation, biogeography, and speciation with twentiethcentury efforts to understand genetic inheritance and genotype-phenotype relations was at once highly formal and mechanistic. While some researchers set about the “wet” work of characterizing genes, alleles, chromosomes, and their products and interactions, others built mathematical models that illuminated Darwinian concepts like “fitness” and “selection” against a genetic backdrop.
Some of this work is presented in the discussion of evolution and ecology below (§4). It is outside the scope of this essay to discuss the development of theoretical biology in any detail, but it is important to note that several of the biological sciences, including population genetics, epidemiology, and ecosystem ecology, enjoy rich traditions of formal modeling while others are comparative and still others are experimental. Often more than one of these broad approaches is practiced within a single biological science, or even to take up a single research question.Quantitative approaches to biological systems are now widespread. In addition to the population genetics tradition begun by R.A. Fisher, Sewall Wright, and J.B.S. Haldane in the early part of the twentieth century, game-theoretical (Maynard Smith 1982) and multi-level (Wilson 1975) approaches to natural selection are in wide use, as are differential equations that describe population dynamics as a result of predator-prey interactions (McLaughlin and Roughgarden 1991), and covariance techniques that model the contribution of selection to change over generations (Price 1970, Wade 1985, Queller 1992). There are also very new quantitative approaches to ecosystem ecology (Sterner and Elser 2002, Elser and Hamilton 2007) and to allometry and metabolic scaling (West, Brown, and Enquist 1997). While it is true that Charles Darwin's On the Origin of Species (1859) contains no mathematics at all, it is not true that even basic evolutionary biology contains no highly articulated theories, nor theories that are informed by mathematical models.
Formal models have been crucial to biology's development, and have issued in some simple, general statements about the biological world. Biologists and philosophers of biology have therefore continued to ask whether there are laws of biology, and how these might compare with laws of physics (Rosenberg 1994, Mitchell 2003, Brandon 2006, Hamilton 2007). Others have asked what the models mean: do abstract and highly idealized models connect with the biological world? If so, what is the appropriate relationship between the model and the world? (Levins 1966, Wimsatt 1981, Odenbaugh 2006).
Not all biology is paper-and-pencil theorizing, of course, and this has led other researchers to think about the relationship between the epistemic and social constraints on the “wetter” aspects of biology and other sciences in contrast to formal approaches (Knorr Cetina 1999, Winther 2006).A second common misconception is that biological kinds - particularly species - are unproblematic natural kinds. As we see below in the discussion of species (§3) and levels of selection (§5), some of the most important and interesting conceptual problems biologists are facing arise because it is unclear precisely what the object of study is, how it relates to other objects, and where the edges of biological objects are to be located. This holds for studies of everything from genes to global biodiversity, partly because evolutionary theory requires that there are populations and that they vary, but is silent about what sorts of populations there are, precisely which ones are subject to natural selection and other evolutionary processes, and how they are bounded as they grade into one another (Maynard Smith 1988, Okasha 2006).
With these considerations in mind, we turn to systematics, one of the sciences most responsible for describing the diversity of the living world, understanding its patterns, and discovering the historical and hierarchical relations between organisms and taxa.
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