The most consistent definition of fitness makes it a static property of organisms. However, this is not how fitness is used in many evolutionary models. In those models, fitness is permitted to vary with an organism’s circumstances. According to this second conception, fitness is dynamic. There is consequently tension between these two conceptions of fitness. One recently proposed solution suggests resorting to conditional properties. We argue, however, that this solution is unsatisfactory. Using a very simple model, we show that it (...) can lead to incompatible fitness values and indecision about whether selection actually occurs. (shrink)

That biology provides explanations is not open to doubt. But how it does so must be a vexed question for those who deny that biology embodies laws or other generalizations with the sort of explanatory force that the philosophy of science recognizes. The most common response to this problem has involved redefining law so that those grammatically general statements which biologists invoke in explanations can be counted as laws. But this terminological innovation cannot identify the source of biology's explanatory power. (...) I argue that because biological science is historical, the problem of biological explanation can be assimilated to the parallel problem in the philosophy of history, and that the problem was solved by Carl Hempel. All we need to do is recognize that the only laws that biology—in all its compartments from the molecular onward—has or needs are the laws of natural selection. (shrink)

We argue that a fashionable interpretation of the theory of natural selection as a claim exclusively about populations is mistaken. The interpretation rests on adopting an analysis of fitness as a probabilistic propensity which cannot be substantiated, draws parallels with thermodynamics which are without foundations, and fails to do justice to the fundamental distinction between drift and selection. This distinction requires a notion of fitness as a pairwise comparison between individuals taken two at a time, and so vitiates the interpretation (...) of the theory as one about populations exclusively. (shrink)

The central point of this essay is to demonstrate the incommensurability of ‘Darwinian fitness’ with the numeric values associated with reproductive rates used in population genetics. While sometimes both are called ‘fitness’, they are distinct concepts coming from distinct explanatory schemes. Further, we try to outline a possible answer to the following question: from the natural properties of organisms and a knowledge of their environment, can we construct an algorithm for a particular kind of organismic life-history pattern that itself will (...) allow us to predict whether a type in the population will increase or decrease relative to other types? Introduction Darwinian fitness Reproductive fitness and genetical models of evolution The models of reproductive fitness 4.1 The Standard Viability Model 4.2 Frequency-dependent selection 4.3 Fertility models 4.4 Overlapping generations Fitness as outcome 5.1 Fitness as actual increase in type 5.2 Fitness as expected increase in type 5.2.1 Expected increase within a generation 5.2.2 Expected increase between generations 5.2.3 Postponed reproductive fitness effects The book-keeping problem Conclusion. (shrink)

The concept of fitness has generated a lot of discussion in philosophy of biology. There is, however, relative agreement about the need to distinguish at least two uses of the term: ecological fitness on the one hand, and population genetics fitness on the other. The goal of this paper is to give an explication of the concept of ecological fitness by providing a reconstruction of the theory of natural selection in which this concept was framed, that is, based on the (...) way the theory was put to use in Darwin’s main texts. I will contend that this reconstruction enables us to account for the current use of the theory of natural selection. The framework presupposed in the analysis will be that of metatheoretical structuralism. This framework will provide both a better understanding of the nature of ecological fitness and a more complete reconstruction of the theory. In particular, it will provide what I think is a better way of understanding how the concept of fitness is applied through heterogeneous cases. One of the major advantages of my way of thinking about natural selection theory is that it would not have the peculiar metatheoretical status that it has in other available views. I will argue that in order to achieve these goals it is necessary to make several concepts explicit, concepts that are frequently omitted in usual reconstructions. (shrink)

According to many philosophers and scientists, human sociality is explained by our unique capacity to “share” attitudes with others. The conditions under which mental states are shared have been widely debated in the past two decades, focusing especially on the issue of their reducibility to individual intentionality and the place of collective intentions in the natural realm. It is not clear, however, to what extent these two issues are related and what methodologies of investigation are appropriate in each case. In (...) this article, I propose a solution that distinguishes between epistemic and ontological interpretations of the demand for the conditions of reduction of collective intentionality. While the philosophical debate has contributed important insights into the former, recent advances in the cognitive sciences offer novel resources to tackle the latter. Drawing on Michael Tomasello’s research in the ontogeny of shared intentionality in early instances of interaction based on joint attention, I propose an empirically informed argument of what it would take to address the ontological question of irreducibility, thus making a step forward in the naturalization of collective intentionality. (shrink)

In several places we have argued that ‘fitness’ is a primitive term with respect to the theory of evolution properly understood. These arguments have relied heavily on the axiomatization of the theory provided by one of us. In contrast, both John Beatty and Robert Brandon have separately argued for a “propensity“ interpretation of “fitness” ; and in Brandon and Beatty they attack our view that “fitness“ is a primitive term in evolutionary theory, concluding that a definition by way of propensities (...) is possible and preferable. Here we reply to their criticisms, and argue that, at most, the view that fitness is a statistical propensity is a terminological variant on our thesis that it is a primitive in evolutionary theory. (shrink)

We attempt a conclusive resolution of the debate over whether the principle of natural selection (PNS), especially conceived as the `principle' of the `survival of the fittest', is a tautology. This debate has been largely ignored for the past 15 years but not, we think, because it has actually been settled. We begin by describing the tautology objection, and situating the problem in the philosophical and biology literature. We then demonstrate the inadequacy of six prima facie plausible reasons for believing (...) that the tautology debate has been satisfactorily resolved (the PNS is strictly a methodological principle; scientific theories can contain tautologies; the scope of the PNS has been reduced; theories should be understood as models and not exceptionless laws; the widespread acceptance of the propensity interpretation of fitness; and the abandonment of operationalism and verificationism). We proceed to a detailed discussion of Brandon's law (D) describing the PNS, and show that law (D) seriously misrepresents the structure of evolution by natural selection. In the final sections, we provide and defend a novel reinterpretation of the structure of the principle (or, we prefer, model) of evolution by natural selection. (shrink)

The notion of fitness is usually equated to reproductive success. However, this actualist approach presents some difficulties, mainly the explanatory circularity problem, which have lead philosophers of biology to offer alternative definitions in which fitness and reproductive success are distinguished. In this paper, we argue that none of these alternatives is satisfactory and, inspired by Mumford and Anjum’s dispositional theory of causation, we offer a definition of fitness as a causal dispositional property. We argue that, under this framework, the distinctiveness (...) that biologists usually attribute to fitness—namely, the fact that fitness is something different from both the physical traits of an organism and the number of offspring it leaves—can be explained, and the main problems associated with the concept of fitness can be solved. Firstly, we introduce Mumford and Anjum's dispositional theory of causation and present our definition of fitness as a causal disposition. We explain in detail each of the elements involved in our definition, namely: the relationship between fitness and the functional dispositions that compose it, the emergent character of fitness, and the context-sensitivity of fitness. Finally, we explain how fitness and realized fitness, as well as expected and realized fitness are distinguished in our approach to fitness as a causal disposition. (shrink)

En uno de los ataques más reiterados a Darwin, que todavía subsiste en la literatura actual, se señala que la teoría de la selección natural es tautológica, analítica o, al menos, irrefutable. En docenas de artículos, diversos autores han señalado las condiciones en que la selección natural quedaría refutada, intentando mostrar que no carece de contenido empírico. La estrategia seguida en este trabajo será otra. Teniendo en cuenta que la crítica de tautologicidad o irrefutabilidad ha sido esgrimida contra leyes fundamentales (...) de otras teorías, insertaré la discusión en un marco metateórico más amplio. Para discutir el estatus del segundo principio de la mecánica clásica, Moulines introduce el concepto de "principio guía". Los principios guía no serían contrastables directamente, sino a través de especializaciones. Desde mi punto de vista, considerar a la selección natural como principio guía permitiría explicar por qué muchos la han considerado tautológica y cómo esto no implica vacuidad. One of the most repeated objections to Darwin, still present in contemporary literature, outlines that theory of natural selection is tautological, analytical or at least irrefutable. There are many authors that point out the conditions in which natural selection would be refuted, trying to prove that it doesn't lack of empirical content. This essay will work on a different strategy. Taking into account that tautological or irrefutable criticism has been put forward against other theories' fundamental laws; I will insert the argumentation in a wider theoretical frame. To argue about the status of the second principle about classic mechanical Moulines introduces the 'guiding principle' concept. The guiding principles wouldn't be directly contrastable. The only way in which they could be contrastable would be through special laws. From my point of view natural selection, considered as the guiding principle, would explain why many thinkers had considered it a tautology and how this does not imply vacuity. (shrink)

Following Wallace’s suggestion, Darwin framed his theory using Spencer’s expression “survival of the fittest”. Since then, fitness occupies a significant place in the conventional understanding of Darwinism, even though the explicit meaning of the term ‘fitness’ is rarely stated. In this paper I examine some of the different roles that fitness has played in the development of the theory. Whereas the meaning of fitness was originally understood in ecological terms, it took a statistical turn in terms of reproductive success throughout (...) the 20th Century. This has lead to the ever-increasing importance of sexually reproducing organisms and the populations they compose in evolutionary explanations. I will argue that, moving forward, evolutionary theory should look back at its ecological roots in order to be more inclusive in the type of systems it examines. Many biological systems can only be satisfactorily accounted for by offering a non-reproductive account of fitness. This argument will be made by examining biological systems with very small or transient population structures. I argue this has significant consequences for how we define Darwinism, increasing the significance of survival over that of reproduction. (shrink)

This dissertation focuses on teleology and functions in biology. More precisely, it focuses on the scientific legitimacy of teleofunctional attributions and explanations in biology. It belongs to a multi-faceted debate that can be traced back to at least the 1970s. One aspect of the debate concerns the naturalization of functions. Most authors try to reduce, translate or explain functions and teleology in terms of efficient causes so that they find their place in the framework of the natural sciences. Our approach (...) here is radically different, as we question the premise that teleological explanations are disguised causal explanations. On the contrary, we defend that they are acceptable in natural sciences and in biology in particular. We challenge the idea that teleological explanations are immature causal explanations, as well as the idea that teleology and functions are some sort of intentional explanations. We therefore reject the accusations of anthropomorphism, vitalism and finalism. On the contrary, we defend that teleology, causality and intentionality correspond to different, autonomous and complementary modes of representation of the outside world. -/- ———[FRANÇAIS]——— -/- Ce travail de thèse porte sur la téléologie et les fonctions en biologie. Plus précisément, il porte sur la légitimité scientifique des attributions et des explications téléofonctionnelles en biologie. Il s’inscrit dans le cadre d’un débat à plusieurs facettes que l’on peut faire remonter au moins jusqu’aux années 1970 et qui est encore très actif aujourd’hui. L’un des aspects du débat porte sur la naturalisation des fonctions, c’est-à-dire sur la manière de les réduire, de les traduire ou de les expliciter en termes de causes efficientes de sorte qu’elles trouvent leur place dans le cadre des sciences de la nature. Notre approche ici est radicalement différente, car nous remettons en question la prémisse selon laquelle les explications téléologiques seraient des explications causales déguisées. Nous défendons au contraire qu’elles sont acceptables en tant que telles aussi bien de façon générale que dans le domaine scientifique et en particulier en biologie. De façon générale, nous remettons en question l’idée selon laquelle la pensée téléologique serait une pensée causale immature, ainsi que sa dépendance présumée vis-à-vis de la psychologie, c’est-à-dire de l’intentionnalité. Nous rejetons donc les accusations d’anthropomorphisme, de vitalisme et de finalisme formulées contre elle. Nous défendons au contraire que la téléologie, la causalité et l’intentionnalité correspondent à des modes différents, autonomes et complémentaires de représentation du monde extérieur. (shrink)

In recent years, some have claimed that a Darwinian perspective will revolutionize the study of human society and culture. This project is viewed with disdain and suspicion, on the other hand, by many practicing social scientists. This article seeks to clear the air in this heated debate by dissociating two claims that are too often assumed to be inseparable. The first is the ‘ontological’ claim that Darwinian principles apply, at some level of abstraction, to human society and culture. The second (...) is the more ‘pragmatic’ claim that this observation necessitates substantial changes in the practices of social scientists. Even if some version of the first claim is true, I argue – which I believe is quite likely – the second does not follow. This observation ought to chasten the most overzealous advocates of Darwinian social science, as well as softening the instinctive resistance of many social scientists and historians to the genuine insights enabled by a Darwinian approach. The conclusion discusses these insights, the most important of which is a methodological prescription for normative theory. (shrink)

In an incendiary 2010 Nature article, M. A. Nowak, C. E. Tarnita, and E. O. Wilson present a savage critique of the best-known and most widely used framework for the study of social evolution, W. D. Hamilton’s theory of kin selection. More than a hundred biologists have since rallied to the theory’s defence, but Nowak et al. maintain that their arguments ‘stand unrefuted’. Here I consider the most contentious claim Nowak et al. defend: that Hamilton’s rule, the core explanatory principle (...) of kin selection theory, ‘almost never holds’. I first distinguish two versions of Hamilton’s rule in contemporary theory: a special version (HRS) that requires restrictive assumptions, and a general version (HRG) that does not. I then show that Nowak et al. are most charitably construed as arguing that HRS almost never holds, while HRG buys its generality at the expense of explanatory power. While their arguments against HRS are fairly uncontroversial, their arguments against HRG are more contentious, yet these have been largely overlooked in the ensuing furore. I consider the arguments for and against the explanatory value of HRG, with a view to assessing what exactly is at stake in the debate. I suggest that the debate hinges on issues concerning the causal interpretability of regression coefficients, and concerning the explanatory function Hamilton’s rule is intended to serve. (shrink)

Sustained controversy over a philosophical issue is often times symptomatic of differing commitments at a more fundamental philosophical level. I will argue that two current debates over the foundations of the theory of natural selection are cases in point. Alexander Rosenberg, at times together with Mary Williams, challenges what is becoming received orthodoxy about the foundations of this theory. He argues that the currently popular propensity interpretation of fitness does not legitimize explanations in terms of natural selection, and that furthermore, (...) the biological fields which typically study the ways in which selection pressures originate in the organism/environment complex are not in fact part of the theory of natural selection at all. His foils in the first case are Robert Brandon, John Beatty and Susan Mills;2 on the second issue he is engaged in debate with Elliott Sober.3 We will see that, although the controversies are ostensibly about the interpretation of fitness, the issues, at bottom, involve the nature of scientific explanation. (shrink)

The purpose of this paper is to defend, contra Fodor and Piattelli-Palmarini (F&PP), that the theory of natural selection (NS) is a perfectly bona fide empirical unified explanatory theory. F&PP claim there is nothing non-truistic, counterfactual-supporting, of an “adaptive” character and common to different explanations of trait evolution. In his debate with Fodor, and in other works, Sober defends NS but claims that, compared with classical mechanics (CM) and other standard theories, NS is peculiar in that its explanatory models are (...) a priori (a trait shared with few other theories). We argue that NS provides perfectly bona fide adaptive explanations of phenotype evolution, unified by a common natural-selection guiding principle. First, we introduce the debate and reply to F&PP’s main argument against NS. Then, by reviewing different examples and analyzing Fisher’s model in detail, we show that NS explanations of phenotypic evolution share a General Natural Selection Principle. Third, by elaborating an analogy with CM, we argue against F&PP’s claim that such a principle would be a mere truism and thus explanatorily useless, and against Sober’s thesis that NS models/explanations have a priori components that are not present in CM and other common empirical theories. Irrespective of differences in other respects, the NS guiding principle has the same epistemic status as other guiding principles in other highly unified theories such as CM. We argue that only by pointing to the guiding principle-driven nature that it shares with CM and other highly unified theories, something no-one has done yet in this debate, one can definitively show that NS is not defective in F&PP’s sense: in the respects relevant to the debate, Natural Selection is as defective and as epistemically peculiar as Classical Mechanics and other never questioned theories. (shrink)

In this article I argue that we should pay extra attention to the ecological dimension of natural selection. By this I mean that we should view natural selection primarily as acting on the outcomes of the interactions organisms have with their environment, which influences their relative reproductive output. A consequence of this view is that natural selection is not sensitive to what system of inheritance ensures reoccurrences of organism-environment interactions over generations. I end by showing the consequences of this view (...) when looking at how processes like niche construction and the Baldwin effect relate to natural selection. (shrink)

The supervenience and multiple realizability of biological properties have been invoked to support a disunified picture of the biological sciences. I argue that supervenience does not capture the relation between fitness and an organism's physical properties. The actual relation is one of causal dependence and is, therefore, amenable to causal explanation. A case from optimality theory is presented and interpreted as a microreductive explanation of fitness difference. Such microreductions can have considerable scope. Implications are discussed for reductive physicalism in evolutionary (...) biology and for the unity of science. (shrink)

In what follows, I suggest that it makes good sense to think of the truth of the probabilistic generalizations made in the life sciences as metaphysically grounded in stochastic mechanisms in the world. To further understand these stochastic mechanisms, I take the general characterization of mechanism offered by MDC :1–25, 2000) and explore how it fits with several of the going philosophical accounts of chance: subjectivism, frequentism, Lewisian best-systems, and propensity. I argue that neither subjectivism, frequentism, nor a best-system-style interpretation (...) of chance will give us what we need from an account of stochastic mechanism, but some version of propensity theory can. I then draw a few important lessons from recent propensity interpretations of fitness in order to present a novel propensity interpretation of stochastic mechanism according to which stochastic mechanisms are thought to have probabilistic propensities to produce certain outcomes over others. This understanding of stochastic mechanism, once fully fleshed-out, provides the benefits of allowing the stochasticity of a particular mechanism to be an objective property in the world, a property investigable by science, a way of quantifying the stochasticity of a particular mechanism, and a way to avoid a problematic commitment to the causal efficacy of propensities. (shrink)

This paper argues that fitness is most usefully understood as those properties of organisms that are explanatory of survival in the broadest sense, not merely descriptive of reproductive success. Borrowing from Rosenberg and Bouchard , fitness in this sense is ecological in that it is defined by the interactions between organisms and environments. There are three sorts of ecological fitness: the well-documented ability to compete, the ability to cooperate , and a third sense of fitness that has received insufficient attention (...) in evolutionary theory, the ability to construct. Following Lotka, it can be understood thermodynamically as the ability to maintain or enlarge the energy-circulating capacity of an ecosystem. An organism that does this could end with its gene frequency unchanged but its probability of survival enhanced since it would sustain or increase the total carrying capacity of its ecosystem. Photosynthesizers and other autotrophs are obvious candidates for organisms that are fit in the constructive sense, but any organisms, including heterotrophs, can exhibit constructive fitness if they have some mechanism for channeling external flows of free energy into their ecosystems. I will briefly examine the prospects for the human species in the light of these considerations. (shrink)

Fitness is a central but notoriously vexing concept in evolutionary biology. The propensity interpretation of fitness is often regarded as the least problematic account for fitness. It ties an individual's fitness to a probabilistic capacity to produce offspring. Fitness has a clear causal role in evolutionary dynamics under this account. Nevertheless, the propensity interpretation faces its share of problems. We discuss three of these. We first show that a single scalar value is an incomplete summary of a propensity. Second, we (...) argue that the widespread method of “abstracting away” environmental idiosyncrasies by averaging over reproductive output in different environments is not a valid approach when environmental changes are irreversible. Third, we point out that expanding the range of applicability for fitness measures by averaging over more environments or longer time scales (so as to ensure environmental reversibility) reduces one's ability to distinguish selectively relevant differences among individuals because of mutation and eco‐evolutionary feedbacks. This series of problems leads us to conclude that a general value of fitness that is both explanatory and predictive cannot be attained. We advocate for the use of propensity‐compatible methods, such as adaptive dynamics, which can accommodate these difficulties. (shrink)

Using a classical life history model (the Smith & Fretwell model of the evolution of offspring size), it is demonstrated that even in the presence of overwhelming empirical support, the testability of predictions derived from evolutionary models can give no guarantee that the underlying fitness concept is sound. Non-awareness of this problem may cause considerable justified but avoidable criticism. To help understanding the variable use of fitness in evolutionary models and recognizing potentially problematic areas which need careful consideration, a hierarchical (...) classification of definitions of fitness used in evolutionary models is presented. As a conclusion, it is advocated to use the term fitness more conscientiously than currently often practised and to think more about ways to develop fitness-free evolutionary theories compatible with Darwin's ideas. (shrink)

Recent attempts to clarify the fitness in evolutionary theory as a propensity (Brandon 1978; Brandon and Beatty 1984; Burian 1983; Mills and Beatty 1979; Sober 1984a, 1984b) or as a primitive theoretical term (Rosenberg 1983, 1985; Williams 1970, Williams and Rosenberg 1985) all miss the mark in clarifying the empirical content and explanatory power of natural selection theory.I shall argue that the crucial distinction missing in these accounts is between the sense of fitness common in population genetics as actual relative (...) rate of increase of genotypes and fitness in the more ordinary sense--and Darwin’s--of adaptedness of organisms. The relation between these senses of ‘fitness’ is that fitness as actual reproduction success depends on, is a function of, variables representing adaptive capacities and environmental properties. (shrink)