We show how two iterated products of selection functions can both be used in conjunction with systemTto interpret, via the dialectica interpretation and modified realizability, full classical analysis. We also show that one iterated product is equivalent over systemTto Spector’s bar recursion, whereas the other isT-equivalent to modified bar recursion. Modified bar recursion itself is shown to arise directly from the iteration of a different binary product of ‘skewed’ selection functions. Iterations of the dependent binary products (...) are also considered but in all cases are shown to beT-equivalent to the iteration of the simple products. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Philosophy, Psychiatry, & Psychology 12.4 (2005) 343-348 [Access article in PDF] Doomed by Nature: The Inevitable Failure of our Naturally Selected Functions Andreas De Block Keywords psychoanalysis, Darwinism, evolutionary psychiatry, pathogenic metaphysics In their very thoughtful and stimulating replies, the three commentators foreground several topics crucial for both psychoanalysis and philosophical psychiatry. In my short response, I focus primarily on what the commentators believe to be the paper's (...) main shortcomings. The first critique reads as follows: Freud never claimed that the Homo sapiens is a fundamentally sick animal, but in fact thought that normalcy is possible and that normal behavior need not be interpreted as neurotic, perverse or psychotic. The second is that current Darwinian psychiatry does not substantiate the view that Homo sapiens is essentially an ill animal, whatever Freud's position might be. Third and last, the proposal that all human beings are ill to the core seems to be more of a religious slogan than a scientifically useful description. What Freud Really Said A transhistorical approach to Freud's work is far from simple, considering that it spans a period of over forty years and that it underwent considerable changes during that time. Not only did Freud introduce some radically new concepts during that time, such as narcissism and the death drive. Also, he regularly changed his position on the aim of psychoanalytic therapy, the ontogenesis of anxiety, and the nature of human sexuality. That Freud sometimes saw homosexuality as an inborn drive did not keep him on other occasions from thinking that homosexual desire was a result of the repression or projection of an oedipal (heterosexual) drive. Examples like these show that any exegesis of Freud's writings inevitably has to deal with some tensions. Freud's work contains numerous apparent, as well as real, contradictions, so that it is no surprise at all that Katherine Morris can produce textual evidence "proving" that Freud never held the view I attribute to him. According to her, Freud thought that we are not all neurotics and that normalcy is possible.I do not deny that several passages in Freud's work underscore the possibility of non-neurotic normalcy. Indeed, Freudian theory even describes processes—sublimation, the transformation from Id to Ego, the resolution of the oedipal complex, among others—that explain how human beings can escape neurosis and other mental disorders. But Freud's illustrations of these mechanisms or processes make clear that he could not conceive [End Page 343] of a nonpathogenic psychodynamics. Consider, for instance, how Freud emphasizes throughout his study of Leonardo da Vinci that Leonardo's sublimations make him extremely vulnerable to psychic exhaustion or "neurasthenia" (1910). Freud never tires of repeating that there is only a gradual difference between a neurotic patient and Leonardo da Vinci, the sublimating ("healthy") artist and scientist.Morris (2005) is right, of course, in arguing that a gradual difference between normality and mental illness does not imply that there is no difference at all. Quantity should not be thought the opposite of quality, because small quantitative differences can transform an "articulation" into a "breach." To use Hegel's famous example, there is a continuum between 110° C and -10° C, but everybody knows that that water evaporates above 100° C and freezes below 0° C. Applied to mental disorders, quantitative differences in levels of testosterone and serotonin may lead to qualitative differences in behavior; in other words, categorical and dimensional approaches to mental illnesses are not mutually exclusive. Having established that, we now need to take a closer look at how Freud articulated the differences between seemingly normal individuals and the mentally ill.Freud held that neurosis, psychosis, and perversion are caused by the interplay between instincts and defense mechanisms. Further, he thought that the pathogenic instincts were almost exclusively sexual. Now, although it is true that he sometimes recognized that the fear of death and the death drive are important factors for psychic life (Deeley 2005) and for the etiology of psychosis, more often than not he interpreted the fear of death as a symbolization of... (shrink)

In this paper I defend an etiological theory of biological functions (according to which the proper function of a trait is the effect for which it was selected by natural selection) against three objections which have been influential. I argue, contrary to Millikan, that it is wrong to base our defense of the theory on a rejection of conceptual analysis, for conceptual analysis does have an important role in philosophy of science. I also argue that biology requires a (...) normative notion of a "proper function", and that a normative notion is not ahistorical. (shrink)

A common misunderstanding of the selected effects theory of function is that natural selection operating over an evolutionary time scale is the only functionbestowing process in the natural world. This construal of the selected effects theory conflicts with the existence and ubiquity of neurobiological functions that are evolutionary novel, such as structures underlying reading ability. This conflict has suggested to some that, while the selected effects theory may be relevant to some areas of evolutionary biology, its relevance to (...) neuroscience is marginal. This line of reasoning, however, neglects the fact that synapses, entire neurons, and potentially groups of neurons can undergo a type of selection analogous to natural selection operating over an evolutionary time scale. In the following, I argue that neural selection should be construed, by the selected effect theorist, as a distinct type of function-bestowing process in addition to natural selection. After explicating a generalized selected effects theory of function and distinguishing it from similar attempts to extend the selected effects theory, I do four things. First, I show how it allows one to identify neural selection as a distinct function-bestowing process, in contrast to other forms of neural structure formation such as neural construction. Second, I defend the view from one major criticism, and in so doing I clarify the content of the view. Third, I examine drug addiction to show the potential relevance of neural selection to neuroscientific and psychological research. Finally, I endorse a modest pluralism of function concepts within biology. (shrink)

Despite the voluminous literature on biological functions produced over the last 40 years, few philosophers have studied the concept of function as it is used in neuroscience. Recently, Craver (forthcoming; also see Craver 2001) defended the causal role theory against the selected effects theory as the most appropriate theory of function for neuroscience. The following argues that though neuroscientists do study causal role functions, the scope of that theory is not as universal as claimed. Despite the strong prima (...) facie superiority of the causal role theory, the selected effects theory (when properly developed) can handle many cases from neuroscience with equal facility. It argues this by presenting a new theory of function that generalizes the notion of a ‘selection process’ to include processes such as neural selection, antibody selection, and some forms of learning—that is, to include structures that have been differentially retained as well as those that have been differentially reproduced. This view, called the generalized selected effects theory of function, will be defended from criticism and distinguished from similar views in the literature. (shrink)

1. IntroductionIn What Biological Functions Are and Why They Matter, Justin Garson offers a novel theory of biological functions, the generalized selected effects (GSE) theory.1 He presents the theory in a clear and comprehensive way, defends it against various objections and applies it to different areas of philosophy, including the philosophy of psychiatry, the debate about mechanisms and the debate about teleosemantic theories of mental content.2Like other proponents of the aetiological approach to functions, Garson maintains that a (...) trait’s biological functions are grounded in its selectional history. However, his GSE theory differs from standard versions of the aetiological approach – so-called selected effects (SE) theories – in a crucial respect: while SE theories assume that all biological functions must ultimately be grounded in phylogenetic processes of natural selection or other (closely analogous) processes of differential reproduction (Millikan 1984: 15–82, Neander 1991, Godfrey-Smith 1994), the GSE theory allows that functions may also be grounded in processes of differential retention (see §2 for details). Garson forcefully argues that this broader account is theoretically well-motivated and has significant advantages over standard SE accounts when it comes to accommodating certain important classes of ontogenetically determined functions. (shrink)

Justin Garson has recently argued that proper functions are proximal activities of traits selected by phylogenetic or ontogenetic selection processes, and that traits are dysfunctional only if they cannot perform their proper functions for constitutional reasons. We partially agree with Garson, but reject the view that functions are proximal activities, as well as his account of dysfunctions. Instead, we propose our own theory that biological functions are selected dispositions and that a trait is dysfunctional in (...) virtue of not having the dispositions for which it was selected. This account can explain both defects (or dysfunctions in Garson’s sense) and dysfunctions due to environmental factors. Moreover, it offers a neat way to explain the graduality of dysfunction. (shrink)

In this paper, we compare the mechanisms of protein synthesis and natural selection. We identify three core elements of mechanistic explanation: functional individuation, hierarchical nestedness or decomposition, and organization. These are now well understood elements of mechanistic explanation in fields such as protein synthesis, and widely accepted in the mechanisms literature. But Skipper and Millstein have argued that natural selection is neither decomposable nor organized. This would mean that much of the current mechanisms literature does not apply to (...) the mechanism of natural selection.We take each element of mechanistic explanation in turn. Having appreciated the importance of functional individuation, we show how decomposition and organization should be better understood in these terms. We thereby show that mechanistic explanation by protein synthesis and natural selection are more closely analogous than they appear—both possess all three of these core elements of a mechanism widely recognized in the mechanisms literature. (shrink)

The goal of this essay is to assess the Selected-Effects Etiological Theory of biological function, according to which a trait has a function F if and only if it has been selected for F. First, I argue that this approach should be understood as describing the paradigm case of functions, rather than as establishing necessary and sufficient conditions for function possession. I contend that, interpreted in this way, the selected-effects approach can explain two central properties of functions and (...) can satisfactorily address some recent counterexamples. This reading, however, shows that there is only a partial overlap between biological functions and selected effects, so the former cannot be reduced to the latter. Finally, I maintain that this result is still compatible with a naturalistic theory of function that appeals to some evolutionary process. (shrink)

This volume handles in various perspectives the concept of function and the nature of functional explanations, topics much discussed since two major and conflicting accounts have been raised by Larry Wright and Robert Cummins’s papers in the 1970s. Here, both Wright’s ”etiological theory of functions’ and Cummins’s ”systemic’ conception of functions are refined and elaborated in the light of current scientific practice, with papers showing how the ”etiological’ theory faces several objections and may in reply be revisited, while (...) its counterpart became ever more sophisticated, as researchers discovered fresh applications for it. Relying on a firm knowledge of the original positions and debates, this volume presents cutting-edge research evincing the complexities that today pertain in function theory in various sciences. Alongside original papers from authors central to the controversy, work by emerging researchers taking novel perspectives will add to the potential avenues to be followed in the future. Not only does the book adopt no a priori assumptions about the scope of functional explanations, it also incorporates material from several very different scientific domains, e.g. neurosciences, ecology, or technology. In general, functions are implemented in mechanisms; and functional explanations in biology have often an essential relation with natural selection. These two basic claims set the stage for this book’s coverage of investigations concerning both ”functional’ explanations, and the ”metaphysics’ of functions. It casts new light on these claims, by testing them through their confrontation with scientific developments in biology, psychology, and recent developments concerning the metaphysics of realization. Rather than debating a single theory of functions, this book presents the richness of philosophical issues raised by functional discourse throughout the various sciences.​ Content Level » Research Keywords » Causal role theory of functions - Determination of content - Ecosystem selection - Etiological theory of function - Evolutionary biology - Functional explanations - Historical concepts in biology - Larry Wright - Neurosciences - New mechanism - Selected effects functions - Systemic theory of functions - William Wimsatt Related subjects » Anthropology & Archaeology - Epistemology & Philosophy of Science - Evolutionary & Developmental Biology - Neuroscience - Philosophy TABLE OF CONTENTS Introduction.- Section I. Biological functions and functional explanations: genes, cells, organisms and ecosystems.- Part 1.A. Functions, organization and development in life sciences.- Chapter 1. William C. Wimsatt. Evolution and the Stability of Functional Architectures.- Chapter 2. Denis M. Walsh. Teleological Emergence: The Autonomy of Evo-Devo.- Chapter 3. Jean Gayon. Does oxygen have a function, or: where should the regress of biological functions stop?.- Part 1.B. Functional pluralism for biologists? Chapter 4. Frédéric Bouchard. How ecosystem evolution strengthens the case for functional pluralism.- Chapter 5. Robert N. Brandon. A general case for functional pluralism.- Chapter 6. Philippe Huneman. Weak realism in the etiological theory of functions.- Section 2. Section II. Psychology, philosophy of mind and technology: Functions in a man’s world.- Part 2.A. 2A. Metaphysics, function and philosophy of mind.- Chapter 7. Carl Craver. Functions and Mechanisms in Contemporary Neuroscience.- Chapter 8. Carl Gillett. Understanding the sciences through the fog of ”functionalism.’.- 2.B. Philosophy of technology, design and functions.- Chapter 9. Fran¸ coise Longy. Artifacts and Organisms: A Case for a New Etiological Theory of Functions.- Chapter 10. Pieter Vermaas and Wybo Houkes. Functions as Epistemic Highlighters: An Engineering Account of Technical, Biological and Other Functions.- Epilogue.- Larry Wright. Revising teleological explanations: reflections three decades on. (shrink)

A complete sourcebook for philosophical discussion of the nature of function in biology.

"Modern History" versions of the etiological theory claim that in order for a trait X to have the proper function F, individuals with X must have been recently favored by natural selection for doing F (Godfrey-Smith 1994; Griffiths 1992, 1993). For many traits with prototypical proper functions, however, such recent selection may not have occurred: traits may have been maintained due to lack of variation or due to selection for other effects. I examine this flaw in (...) Modern History accounts and offer an alternative etiological theory, the Continuing Usefulness account, which appears to avoid such problems. (shrink)

This book explores issues at the core of modern linguistics and cognitive science. Why are all languages similar in some ways and in others utterly different? Why do languages change and change variably? How did the human capacity for language evolve, and how far did it do so as an innate ability? Simon Kirby looks at these questions from a broad perspective, arguing that they can be studied together. The author begins by examining how far the universal properties of language (...) may be explained by examining the way it is used, and how far by the way it is structured. He then considers what insights may be gained by combining functional and formal approaches. In doing so he develops a way of treating language as an adaptive system, in which its communicative and formal roles are both crucial and complementary. In order to test the effectiveness of competing theories and explanations, Simon Kirby develops computational models to show what universals emerge given a particular theory of language use or acquisition. He presents here both the methodology and the results. Function, Selection, and Innateness is important for its argument, its methodology, and its conclusions. It is a powerful demonstration of the value of looking at language as an adaptive system and goes to the heart of current debates on the evolution and nature of language. (shrink)

Invoking its social function can explain why we find a certain functional trait or institution only if we can identify a mechanism whereby the playing of the function connects with the explanandum. That is the main claim in the missing-mechanism critique of functionalism. Is it correct? Yes, if functional explanation is meant to make sense of the actual presence of the trait or institution. No, if it is meant to make sense of why the trait or institution is resilient: why (...) we can rely on it to survive various contingencies. The lesson? Social functionalism should be taken, and may have been taken by its founders, as a programme for explaining resilience. (shrink)

It is widely assumed that selection history accounts of function can support a fully reductive naturalization of functional properties. I argue that this assumption is false. A problem with the alternative causal role account of function in this context is that it invokes the teleological notion of a goal in analysing real function. The selection history account, if it is to have reductive status, must not do the same. But attention to certain cases of selection history in (...) biology, specifically those involving meiotic drive, shows that selection historical explanations are available in the case of items without any plausible function. Making contributions to goals, here fitness, must be introduced as an additional constraint in the analysis, either explicitly, or implicitly by appeal to individual functions or the selection-of/selection-for distinction. (shrink)

I present and defend the generalized selected effects theory (GSE) of function. According to GSE, the function of a trait consists in the activity that contributed to its bearer’s differential reproduction, or differential retention, within a population. Unlike the traditional selected effects (SE) theory, it does not require that the functional trait helped its bearer reproduce; differential retention is enough. Although the core theory has been presented previously, I go significantly beyond those presentations by providing a new argument for GSE (...) and defending it from a recent objection. I also sketch its implications for teleosemantics and philosophy of medicine. (shrink)

Jon Elster and Daniel Little have criticized social scientists for appealing to a mechanism of social selection in functional explanations of social practices. Both believe that there is no such mechanism operative in the social world. I develop and defend an account of functional explanation in which a mechanism of social selection figures centrally. In addition to developing an account of social selection, I clarify what functional hypotheses purport to claim, and re-examine the role of agents’ intentions (...) in functional explanations in an effort to show why a mechanism of social selection is indispensable to adequate functional explanations. (shrink)

The work of Bertrand Russell had a decisive influence on the emergence of analytic philosophy, and on its subsequent development. The prize-winning Russell scholar Peter Hylton presents here some of his most celebrated essays from the last two decades, all of which strive to recapture and articulate Russell's monumental vision. Relating his work to that of other philosophers, particularly Frege and Wittgenstein, and featuring a previously unpublished essay and a helpful new introduction, the volume will be essential for anyone engaged (...) with the history of twentieth-century ideas. (shrink)

The selection strategies of individuals and 2-person cooperative groups were investigated in 5 concept-attainment problems. 2 types of stimulus displays were used: (a) form displays, consisting of geometric forms varying in 6 attributes with 2 levels of each, (b) sequence displays, consisting of 6 plus and/or minus signs in a row. The arrangement of cards in the stimulus displays was ordered or random. The principal results were: (a) 2-person groups used the focusing strategy more, required fewer card choices to (...) solution, and required more time than individuals; (b) form displays resulted in more use of the focusing strategy than sequence displays, with no difference in number of card choices; (c) no difference between ordered and random arrays in use of the focusing strategy or number of card choices. (PsycINFO Database Record (c) 2016 APA, all rights reserved). (shrink)

The present paper revisits the debate between realists about gravitational energy in GR and anti-realists/eliminativists. I re-assess the arguments underpinning Hoefer’s seminal eliminativist stance, and those of their realist detractors’ responses. A more circumspect reading of the former is proffered that discloses where the so far not fully appreciated, real challenges lie for realism about gravitational energy. I subsequently turn to Lam and Read’s recent proposals for such a realism. Their arguments are critically examined. Special attention is devoted to the (...) adequacy of Read’s appeals to functionalism, imported from the philosophy of mind. (shrink)

The present paper revisits the debate between realists about gravitational energy in GR and anti-realists/eliminativists. I re-assess the arguments underpinning Hoefer’s seminal eliminativist stance, and those of their realist detractors’ responses. A more circumspect reading of the former is proffered that discloses where the so far not fully appreciated, real challenges lie for realism about gravitational energy. I subsequently turn to Lam and Read’s recent proposals for such a realism. Their arguments are critically examined. Special attention is devoted to the (...) adequacy of Read’s appeals to functionalism, imported from the philosophy of mind. (shrink)

Associations between language and executive functions are well-established but previous work has often focused more on EFs than on language. To further clarify the language–EF relationship, we assessed several aspects of language and EFs in 431 Swedish children aged 4–6, including selective auditory attention which was measured in an event-related potential paradigm. We also investigated potential associations to age, socioeconomic status, bi-/multilingualism, sex and aspects of preschool attendance and quality. Language and EFs correlated weakly to moderately, indicating that relying (...) on measures of vocabulary alone may overestimate the strength of the language–EF relationship. Contrary to predictions, we found no correlations between selective attention and EFs. There were however correlations between morphosyntactic accuracy and selective auditory attention which is in line with previous work and suggests a specific link between morphosyntax and the ability to suppress irrelevant stimuli. In Sweden, socioeconomic differences are rather small and preschool is universally available, but nevertheless, aspects of parental SES predicted children’s performance on all measures. Bi-/multilingual children performed lower on language also when controlling for SES, highlighting the need for interventions to reduce inequalities in educational outcomes already in preschool. A female advantage was found for both language and EFs, whereas preschool attendance and quality were not significantly related to outcome measures. Future work should include longitudinal studies of language and EF development, include children from diverse SES backgrounds and contribute toward a theoretical framework that further clarifies the language–EF relationship. (shrink)

While the question of whether selected-effects accounts of function or causal-role accounts of function provide the ‘true' functional analysis has given way to a general pluralistic consensus, Philip Kitcher has suggested that different functional accounts allow for unification. I argue that Kitcher's attempt to unify the two functional analyses fails because he adopts the environment-centered perspective on selection as a premise. The premise is undermined by the role niche construction is likely to play in the context of evolution. Moreover, (...) I raise the tentative suggestion that niche construction may threaten the applicability, or at least the relevance, of selected-effects ascriptions. *Received October 2009; revised May 2010. †To contact the author, please write to: Institut für Philosophie Fakultät für Philosophie und Bildungswissenschaft, Universität Wien, Universitätsstraße 7 1010 Wien, Austria; e-mail: [email protected]. (shrink)

In opposition to the etiological conception of biological functions, this paper attempts to show that explanations by natural selection, far from justifying functional attributions, presuppose them, and that these attributions may be understood by appealing to a particular specification of the systemic conception of function, that is, the biological conception of function. This paper argues that the etiological conception of function is based on two fundamental errors: confusing the concept of function with the concept of adaptation, and confusing (...) selectional explanations with functional analyses. This explains the inappropriate demand that those analyses include an etiological explanatory content and make possible the distinction between adaptations and exaptations. (shrink)

Explanatory Externalism states that the only adaptive force in evolution is natural selection. Explanatory Externalism is a central thesis of the Modern Evolutionary Synthesis. The etiological theory of natural selected-effect functions also advocates Explanatory Externalism. According to this theory, natural selection is the process responsible for determining the proper natural functions of traits. However, I will point out several challenges to Explanatory Externalism that are proposed primarily by developmental biology and its various subfields. Based on these (...) challenges, this paper will argue why biological functions cannot be fully explained by the selected-effect theory, i.e., that a theory of biological functions must adopt some kind of Explanatory Internalism. At the end of this paper, I will discuss whether or not Explanatory Internalism entails a pluralistic view of biological functions, and how this discussion is related to the different explanations of fit and diversity found in evolutionary biology. (shrink)

The present paper revisits the debate between realists about gravitational energy in GR and anti-realists/eliminativists. I re-assess the arguments underpinning Hoefer’s seminal eliminativist stance, and those of their realist detractors’ responses. A more circumspect reading of the former is proffered that discloses where the so far not fully appreciated, real challenges lie for realism about gravitational energy. I subsequently turn to Lam and Read’s recent proposals for such a realism. Their arguments are critically examined. Special attention is devoted to the (...) adequacy of Read’s appeals to functionalism, imported from the philosophy of mind. (shrink)

Marketing communication in modern times is similar to the propaganda model, i.e. persuasive communication in all possible fields of exploitation. The last three decades in Central and Eastern Europe constituted a time of transformation in many areas of social, political and economic life. Thanks to immanent changes depending on the economic situation and the clash of demand and supply, it was possible to create functional models in three selected time intervals distinguished by the author (socialism, transformational period and capitalism). The (...) use of functional models gives the opportunity to indicate how many changes have taken place in such a short period of time both in terms of consumer mentality and in satisfying the needs of producers. The basis for the application of this type of operationalization of the idea is the statement that “the functional model consists in mapping the functioning of a given system. It should give an idea of the functions and processes taking place in a given system” (Sabryła, Trzciniecki 1986). The purpose of this article is also to start a discussion on contemporary models of product communication. (shrink)

Firstly, this paper aims to analyze how verbal and visual modes contribute to build two basic components of cartoons: the referenced situation and the fictional situation. Secondly, it aims to unravel the semiotics of this discursive genre by offering a fine-grained picture of modal variations and continuities of the rhetorical resources deployed, by means of which the fictional situation is displayed. The corpus is composed of 50 multimodal cartoons chosen by cartoonists of 22 nationalities as the most representative of their (...) work in the frame of a wide questionnaire. Category analysis and non-parametric statistics were applied. We identified and fleshed out four different types of modal functioning of resources: visual preference, verbal preference, modal flexibility, and genuine multimodal functioning. Even if visual and multimodal metaphor were often in charge of transferring meaning from fiction to the referenced situation, results show that other resources such as antithesis, irony, and syllepsis can become the key resources of cartoons. Findings highlight the multilayered functioning of cartoons, among which plastic features can play a significant role, and provide further evidence in favor of the hyperdetermination of humor hypothesis proposed by Attardo. (shrink)

This article argues that at least very many judgments of homology rest on prior attributions of selected‐effect (SE) function, and that many of the “parts” of biological systems that are rightly classified as homologous are constituted by (are so classified in virtue of) their consequence etiologies. We claim that SE functions are often used in the prior identification of the parts deemed to be homologous and are often used to differentiate more restricted homologous kinds within less restricted ones. In (...) doing so, we discuss recent criticism of this view that has been offered (especially that offered by Paul Griffiths). *Received July 2007; revised November 2008. †To contact the authors, please write to: Department of Philosophy, 201 West Duke Building, Box 90743, Durham, NC 27708; e‐mail: [email protected] or [email protected]. (shrink)

It is tempting to invoke organismal selection as perpetually optimizing the function of any given gene. However, natural selection can drive genic functional change without improvement of biochemical activity, even to the extinction of gene activity. Detrimental mutations can creep in owing to linkage with other selectively favored loci. Selection can promote functional degradation, irrespective of genetic drift, when adaptation occurs by loss of gene function. Even stabilizing selection on a trait can lead to divergence of (...) the underlying molecular constituents. Selfish genetic elements can also proliferate independent of any functional benefits to the host genome. Here we review the logic and evidence for these diverse processes acting in genome evolution. This collection of distinct evolutionary phenomena – while operating through easily understandable mechanisms – all contribute to the seemingly counterintuitive notion that maintenance or improvement of a gene's biochemical function sometimes do not determine its evolutionary fate. (shrink)