Do the sciences aim to uncover the structure of nature, or are they ultimately a practical means of controlling our environment? In Instrumental Biology, or the Disunity of Science, Alexander Rosenberg argues that while physics and chemistry can develop laws that reveal the structure of natural phenomena, biology is fated to be a practical, instrumental discipline. Because of the complexity produced by natural selection, and because of the limits on human cognition, scientists are prevented from uncovering the basic structure of (...) biological phenomena. Consequently, biology and all of the disciplines that rest upon it--psychology and the other human sciences--must aim at most to provide practical tools for coping with the natural world rather than a complete theoretical understanding of it. (shrink)

Darwinism designates a distinctive form of evolutionary explanation for the history and diversity of life on earth. Its original formulation is provided in the first edition of On the Origin of Species in 1859. This entry first formulates ‘Darwin's Darwinism’ in terms of five philosophically distinctive themes: (i) probability and chance, (ii) the nature, power and scope of selection, (iii) adaptation and teleology, (iv) nominalism vs. essentialism about species and (v) the tempo and mode of evolutionary change. Both Darwin and (...) his critics recognized that his approach to evolution was distinctive on each of these topics, and it remains true that, though Darwinism has developed in many ways unforeseen by Darwin, its proponents and critics continue to differentiate it from other approaches in evolutionary biology by focusing on these themes. This point is illustrated in the second half of the entry by looking at current debates in the philosophy of evolutionary biology on these five themes, with a special focus on Stephen Jay Gould's The Structure of Evolutionary Theory. (shrink)

As a number of biologists and philosophers have emphasized, ‘chance’ has multiple meanings in evolutionary biology. Seven have been identified. I will argue that there is a unified concept of chance underlying these seven, which I call the UCC (Unified Chance Concept). I will argue that each is characterized by which causes are consid- ered, ignored, or prohibited. Thus, chance in evolutionary biology can only be under- stood through understanding the causes at work. The UCC aids in comparing the different (...) concepts and allows us to characterize our concepts of chance in probabilistic terms, i.e. provides a way to translate between ‘chance’ and ‘probability’. (shrink)

In 1937, just as Dobzhansky published the book that later generations would laud as the foundation of the modern synthesis, the American Naturnlist published a symposium on "supraspecific variation in nature and in classification." Alfred C. Kinsey, who later became one of America's most controversial intellectuals for his study of basic behaviors in another sort of WASP,1 led off the symposium with a summary of his extensive work on a family of gall wasps, the Cynipidae. In his article, Kinsey strongly (...) advocated the central theme of the developing synthesis: Evolution at all scales, particularly macroevolution, could be explained by the genetic mechanisms observed in laboratories and local populations. He first complained that some geneticists and naturalists were still impeding a synthesis with their insistence upon causal separation of levels: "Just as some of the geneticists have insisted that the laboratory genetics may explain the nature and origin of Mendelian races, but not of natural species, so others indicate that the qualities of higher categories must be explained on bases other than those involved in species" (1937, p. 208). He then defended the central postulate. (shrink)

This paper offers a metaphysics of physical probability in (or if you prefer, truth conditions for probabilistic claims about) deterministic systems based on an approach to the explanation of probabilistic patterns in deterministic systems called the method of arbitrary functions. Much of the appeal of the method is its promise to provide an account of physical probability on which probability assignments have the ability to support counterfactuals about frequencies. It is argued that the eponymous arbitrary functions are of little philosophical (...) use, but that they can be substituted for facts about frequencies without losing the ability to provide counterfactual support. The result is an account of probability in deterministic systems that has a “propensity-like” look and feel, yet which requires no supplement to the standard modern empiricist tool kit of particular matters of fact and principles of physical dynamics. (shrink)

Evolutionary theory is awash with probabilities. For example, natural selection is said to occur when there is variation in fitness, and fitness is standardly decomposed into two components, viability and fertility, each of which is understood probabilistically. With respect to viability, a fertilized egg is said to have a certain chance of surviving to reproductive age; with respect to fertility, an adult is said to have an expected number of offspring.1 There is more to evolutionary theory than the theory of (...) natural selection, and here too one finds probabilistic concepts aplenty. When there is no selection, the theory of neutral evolution says that a gene’s chance of eventually reaching fixation is 1/(2N), where N is the number of organisms in the generation of the diploid population to which the gene belongs. The evolutionary consequences of mutation are likewise conceptualized in terms of the probability per unit time a gene has of changing from one state to another. The examples just mentioned are all “forwarddirected” probabilities; they describe the probability of later events, conditional on earlier events. However, evolutionary theory also uses “backwards probabilities” that describe the probability of a cause conditional on its effects; for example, coalescence theory allows one to calculate the expected number of generations in the past that the genes in the present generation find their most recent common ancestor. (shrink)

Evolutionary theory is thoroughly probabilistic, due to such elements as random mutation, random drift, and stochastic models of speciation and extinction. This uncontroversial claim raises a number of contentious issues: Is evolutionary theory probabilistic in any general sense, or only in a variety of particular, distinct senses? Are these processes inherently probabilistic, or does the use of probabilities simply provide a convenient way to camouflage a multitude of unknown causes? Does chance play an explanatory role in evolutionary theory, and if (...) so, how? My research explores the seemingly disparate meanings of biologists' various usages of the concept of chance in order to shed light on the answers to these questions. ;Recently, philosophers of science have looked to quantum mechanics to settle issues concerning the nature of chance. However, evolutionary theory itself has a decidedly probabilistic character, apart from quantum mechanics; evolutionary theory was given a probabilistic formulation prior to and independently of the development of quantum mechanics. Previous accounts of chance in evolutionary theory have focused primarily on one particular aspect of chance. I examine three distinct areas where chance enters into evolutionary theory in order to provide a comprehensive, synthetic account. Random drift has been the subject of much discussion by philosophers of biology, most notably by Beatty, Brandon, Hodge, Rosenberg, Shanahan, and Sober. My dissertation thus focuses on random drift in order to settle a number of unresolved controversies raised by these philosophers. The discussion of random drift provides a template for exploring random mutation and stochastic models of macroevolution. On the basis of these analyses, I argue that evolutionary theory provides reasons to rethink some of our traditional philosophical ideas about chance. (shrink)

Genetic drift (variously called “random drift”, “random genetic drift”, or sometimes just “drift”) has been a source of ongoing controversy within the philosophy of biology and evolutionary biology communities, to the extent that even the question of what drift is has become controversial. There seems to be agreement that drift is a chance (or probabilistic or statistical) element within population genetics and within evolutionary biology more generally, and that the term “random” isn’t invoking indeterminism or any technical mathematical meaning, but (...) that’s about where agreement ends. Yet genetic drift models are a staple topic in population genetics textbooks and research, with genetic drift described as one of the main factors of evolution alongside selection, mutation, and migration. Some claim that genetic drift has played a major role in evolution (particularly molecular evolution), while others claim it to be minor. This article examines these and other controversies. -/- In order to break through the logjam of competing definitions of drift, this entry begins with a brief history of the concept, before examining various philosophical claims about the proper characterization of drift and whether it can be distinguished from natural selection; the relation of drift to debates over statisticalism; whether drift can be detected empirically and if so, how; and the proper understanding of drift as a model and as a (purported) law. (shrink)