This article defends the Negative View of natural selection explanation, according to which natural selection cannot explain of any given individual why it has the traits it does. Over the years, this view has been criticized on empirical, metaphysical, and explanatory grounds. I review the debate and offer additional reasons for rejecting the empirical and metaphysical objections. The explanatory objection, which holds that the Negative View is rooted in a flawed account of contrastive explanation, initially seems plausible. However, I argue (...) that a closer consideration of the desiderata of contrastive explanation shows that this objection fails as well. (shrink)

We distinguish dynamical and statistical interpretations of evolutionary theory. We argue that only the statistical interpretation preserves the presumed relation between natural selection and drift. On these grounds we claim that the dynamical conception of evolutionary theory as a theory of forces is mistaken. Selection and drift are not forces. Nor do selection and drift explanations appeal to the (sub-population-level) causes of population level change. Instead they explain by appeal to the statistical structure of populations. We briefly discuss the implications (...) of the statistical interpretation of selection for various debates within the philosophy of biologythe `explananda of selection' debate and the `units of selection' debate. (shrink)

There are two general approaches to characterising biological functions. One originates with Cummins. According to this approach, the function of a part of a system is just its causal contribution to some specified activity of the system. Call this the ‘C-function’ concept. The other approach ties the function of a trait to some aspect of its evolutionary significance. Call this the ‘E-function’ concept. According to the latter view, a trait's function is determined by the forces of natural selection. The C-function (...) and E-function concepts are clearly quite different, but there is an important relation between them which heretofore has gone unnoticed. The purpose of this paper is to outline that relation.This is not the first paper to discuss the relation of C-function and E-function. Previous attempts all follow either one of two strategies. The first proposes that the two concepts are ‘unified.’ The other proposes that they are radically distinct and apply to wholly different fields within biology. (shrink)

One approach to assess the explanatory power of natural selection is to ask what type of facts it can explain. The standard list of explananda includes facts like trait frequencies or the survival of particular organisms. Here, I argue that this list is incomplete: natural selection can also explain a specific kind of individual-level fact that involves traits. The ability of selection to explain this sort of fact vindicates the explanatory commitments of empirical studies on microevolution. Trait facts must be (...) distinguished from a closely related kind of fact, that is, the fact that a particular individual x has one trait rather than another. Whether or not selection can explain the latter type of fact is highly controversial. According to the so-called ‘Negative View’ it cannot be explained by selection. I defend the Negative View against Nanay’s objection. (shrink)

Many people argue that history makes a special difference to the subjects of biology and psychology, and that history does not make this special difference to other parts of the world. This paper will show that historical properties make no more or less of a difference to biology or psychology than to chemistry, physics, or other sciences. Although historical properties indeed make a certain kind of difference to biology and psychology, this paper will show that historical properties make the same (...) kind of difference to geology, sociology, astronomy, and other sciences. Similarly, many people argue that nonhistorical properties make a special difference to the nonbiological and the nonpsychological world. This paper will show that nonhistorical properties make the same difference to all things in the world when it comes to their causal behavior and that historical properties make the same difference to all things in the world when it comes to their distributions. Although history is special, it is special in the same way to all parts of the world. (shrink)

Felsenstein’s method of independent contrasts (FIC) is one of the most widely used approaches to the study of correlated evolution. However, it is also quite controversial: numerous researchers have called various aspects of the method into question. Among these objections, there is one that, for two reasons, stands out from the rest: first, it is rather philosophical in nature; and second, it has received very little attention in the literature thus far. This objection concerns Sober’s charge that the FIC is (...) methodologically flawed due to its (seemingly) resting on the assumption that the traits it studies evolved by drift—and thus ruling out selective hypotheses from the start. In this article, I try to rebut this charge. To do this, I first consider a preliminary conceptual worry—the question of how it is even possible for two drift-driven traits to be evolutionarily correlated—and show that it can be answered by noting that the FIC can be seen as being concerned with the investigation of the modularity of the relevant traits. Given this, I then show that Sober’s methodological charge can at least be mitigated by noting that the assumptions behind the FIC do not in fact preclude it from investigating selective hypotheses. I end by pointing out that making this clearer is not just relevant for defending the cogency of the FIC, but also for developing a deeper understanding of correlated evolution in general. (shrink)

Though nativist hypotheses have played a pivotal role in the development of cognitive science, it remains exceedingly obscure how they—and the debates in which they figure—ought to be understood. The central aim of this paper is to provide an account which addresses this concern and in so doing: a) makes sense of the roles that nativist theorizing plays in cognitive science and, moreover, b), explains why it really matters to the contemporary study of cognition. I conclude by outlining a range (...) of further implications of this account for current debate in cognitive science. (shrink)

The naturalistically inclined philosopher of mind faces two related challenges: show how mental content could be part of the natural world, and show how content can be one of the factors responsible for producing behaviour, that is, show that content is not epiphenomenal. One might pursue the first goal with the intent of showing that mental content is epiphenomenal, but it is more likely that the philosopher concerned with showing how content can be naturalized also expects content to be causally (...) efficacious. Indeed, why pursue the first challenge while holding that content is epiphenomenal? Thus these two challenges overlap: show how content can be naturalized without making content epiphenomenal. (shrink)

The explanatory role of natural selection is one of the long-term debates in evolutionary biology. Nevertheless, the consensus has been slippery because conceptual confusions and the absence of a unified, formal causal model that integrates different explanatory scopes of natural selection. In this study we attempt to examine two questions: (i) What can the theory of natural selection explain? and (ii) Is there a causal or explanatory model that integrates all natural selection explananda? For the first question, we argue that (...) five explananda have been assigned to the theory of natural selection and that four of them may be actually considered explananda of natural selection. For the second question, we claim that a probabilistic conception of causality and the statistical relevance concept of explanation are both good models for understanding the explanatory role of natural selection. We review the biological and philosophical disputes about the explanatory role of natural selection and formalize some explananda in probabilistic terms using classical results from population genetics. Most of these explananda have been discussed in philosophical terms but some of them have been mixed up and confused. We analyze and set the limits of these problems. (shrink)

I have recently argued that origin essentialism regarding individual organisms entails that natural selection does not explain why individual organisms have the traits that they do. This paper defends this and related theses against Mohan Matthen's recent objections.

This paper analyzes recent attempts to reject reproduction with lineage formation as a necessary condition for evolution by means of natural selection :560–570, 2008; Stud Hist Philos Sci Part C Stud Hist Philos Biol Biomed Sci 42:106–114, 2011; Bourrat in Biol Philos 29:517–538, 2014; Br J Philos Sci 66:883–903, 2015; Charbonneau in Philos Sci 81:727–740, 2014; Doolittle and Inkpen in Proc Natl Acad Sci 115:4006–4014, 2018). Building on the strengths of these attempts and avoiding their pitfalls, it is argued that (...) a robust formulation of evolution by natural selection without reproduction can be established. The main contribution of this paper is a reformulation of Lewontin’s three principles stating that minimal evolution by natural selection occurs when two conditions are met in a population: fitness-related variation and memory. Paradigmatic evolution by natural selection, which can generate adaptations, takes place when an additional condition is present, namely regeneration. (shrink)

This paper argues that a minimal notion of function and a notion of normal-proper function are used in explaining how bodies and brains operate. Neither is Cummins’ notion, as originally defined, and yet his is often taken to be the clearly relevant notion for such an explanatory context. This paper also explains how adverting to normal-proper functions, even if these are selected functions, can play a significant scientific role in the operational explanations of complex systems that physiologists and neurophysiologists provide, (...) despite a lack of relevant causal efficacy on the part of such functions. (shrink)

The canonical version of the history of twentieth century philosophy of science tells us that Lakatos was Popper’s disciple, but it is rarely mentioned that Popper would have learned anything from Lakatos. The aim of this paper is to examine Lakatos’ influence on Popper’s philosophical system and to argue that Lakatos did have an important, yet somewhat unexpected, impact on Popper’s thinking: he influenced Popper’s evolutionary model for ‘progress’ in science. And Lakatos’ influence sheds new light on why and how (...) Popper continually revised one of the central claims of his philosophy of science: the evolutionary account of scientific theory change. (shrink)

The aim of this paper is to outline a typologyof selection processes, and show that differentsub-categories have different explanatorypower. The basis of this typology of selectionprocesses is argued to be the difference ofreplication processes involved in them. Inorder to show this, I argue that: 1.Replication is necessary for selection and 2.Different types of replication lead todifferent types of selection. Finally, it isargued that this typology is philosophicallysignificant, since it contrasts cases ofselection (on the basis of the replicationprocesses involved in them) (...) whereby selectioncauses adaptation – and, therefore, can beused in explanations of the (real or apparent)teleology of Nature – and cases in whichselection lacks such explanatory power. (shrink)

The concept of population thinking was introduced by Ernst Mayr as the right way of thinking about the biological domain, but it is difficult to find an interpretation of this notion that is both unproblematic and does the theoretical work it was intended to do. I argue that, properly conceived, Mayr’s population thinking is a version of trope nominalism: the view that biological property-types do not exist or at least they play no explanatory role. Further, although population thinking has been (...) traditionally used to argue against essentialism about biological kinds, recently it has been suggested that it may be consistent with at least some forms of essentialism—ones that construe essential properties as relational. I argue that if population thinking is a version of trope nominalism, then, as Mayr originally claimed, it rules out any version of essentialism about biological kinds. (shrink)

One of the most influential arguments against the claim that computers can think is that while our intentionality is intrinsic, that of computers is derived: it is parasitic on the intentionality of the programmer who designed the computer-program. Daniel Dennett chose a surprising strategy for arguing against this asymmetry: instead of denying that the intentionality of computers is derived, he endeavours to argue that human intentionality is derived too. I intend to examine that biological plausibility of Dennett’s suggestion and show (...) that Dennett’s argument for the claim that human intentionality is derived because it was designed by natural selection is based on the misunderstanding of how natural selection works. (shrink)

In this paper, I am clarifying and defending my argument in favor of the claim that cumulative selection can explain adaptation provided that the environmental resources are limited. Further, elaborate on what this limitation of environmental resources means and why it is relevant for the explanatory power of natural selection.

In this paper, I am clarifying and defending my argument in favor of the claim that cumulative selection can explain adaptation provided that the environmental resources are limited. Further, elaborate on what this limitation of environmental resources means and why it is relevant for the explanatory power of natural selection.

Many moral philosophers accept the Debunking Thesis, according to which facts about natural selection provide debunking explanations for certain of our moral beliefs. I argue that philosophers who accept the Debunking Thesis beg important questions in the philosophy of biology. They assume that past selection can explain why you or I hold certain of the moral beliefs we do. A position advanced by many prominent philosophers of biology implies that this assumption is false. According to the Negative View, natural selection (...) cannot explain the traits of individuals. Hence, facts about past selection cannot provide debunking explanations for any of our moral beliefs. The aim of this paper is to explore the conflict between the Debunking Thesis and the Negative View. (shrink)

RESUMENMe propongo examinar críticamente la analogía entre selección natural y condicionamiento operante que Fodor y Piattelli-Palmarini utilizan para sostener que los mismos argumentos que desacreditan la teoría conductista desacreditan la teoría de la selección natural. Estas teorías no son independientes ni conceptual ni históricamente y, por eso, no es razonable hacer una analogía entre ambas con las intenciones que se proponen Fodor y Piattelli-Palmarini. La selección natural es una condición causal del me­ca­nismo de condicionamiento operante, motivo por el cual la (...) refutación de la teoría del condicio­na­miento no puede ser una razón para la refutación de la teoría de la selección natural. ABSTRACTIn this paper I argue against the analogy between natural selection and operant conditioning that Fodor and Piattelli-Palmarini used to argue that the same arguments that discredit the behaviorist theory discredit the theory of natural selection. These theories are not independent either conceptually or historically and, therefore, it is unreasonable to make an analogy between selection and operant conditioning that can serve Fodor and Piattelli-Palmarini's intentions. Natural selection is a causal condition of the mechanism of operant conditioning, so the refutation of the theory of operant conditioning cannot be a reason for the refutation of the theory of natural selection. (shrink)

The “negative view” is the claim that natural selection cannot explain why a particular individual has one trait, rather than another. Here, I modify an example from Lewens (2001) to show that this claim is sometimes false. I then advance a variation on the negative view. It is the claim that selection at the organism level within a lineage cannot explain why a particular individual in that lineage has one allele, rather than another. This formulation better describes the explanatory role (...) of selection. (shrink)

This paper presents an account of the biological populations that can undergo paradigmatic natural selection. I argue for, and develop Peter Godfrey-Smith’s claim that reproductive competition is a core attribute of such populations. However, as Godfrey-Smith notes, it is not the only important attribute. I suggest what the missing element is, co-opting elements of Alan Templeton’s notion of exchangeability. The final framework is then compared to two recent discussions regarding biological populations proposed by Roberta Millstein and Jacob Stegenga.

natural selection may show why all (most, some) humans have an opposable thumb, but cannot show why any particular human has one, Karen Neander ([1995a], [1995b]) argues that this is false because natural selection is 'cumulative'. It is argued here, on grounds independent of its cumulativity, that selection can explain the characteristics of individual organisms subsequent to the event. The difference of opinion between Sober and his critics turns on an ontological dispute about how organisms are identified and individuated. The (...) assumption that Sober needs to make his point is extraneous to population genetics, and, for this reason, gratuitous. (shrink)

In this paper, using a multilevel approach, we defend the positive role of natural selection in the generation of organismal form. Despite the currently widespread opinion that natural selection only plays a negative role in the evolution of form, we argue, in contrast, that the Darwinian factor is a crucial (but not exclusive) factor in morphological organization. Analyzing some classic arguments, we propose incorporating the notion of ‘downward causation’ into the concept of ‘natural selection.’ In our opinion, this kind of (...) causation is fundamental to the operation of selection as a creative evolutionary process. (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)

The rights and wrongs of adaptationism areoften discussed by appeal to what I call theartefact model. Anti-adaptationistscomplain that the use of optimality modelling,reverse engineering and other techniques areindicative of a mistaken and outmoded beliefthat organisms are like well-designedartefacts. Adaptationists (e.g. Dennett 1995)respond with the assertion that viewingorganisms as though they were well designed isa fruitful, perhaps necessary research strategyin evolutionary biology. Anti-adaptationistsare right when they say that techniques likereverse engineering are liable to mislead. This fact does not undermine the artefact (...) modelprecisely because the same techniques misleadus for the same reasons when they are appliedunreflectively to artefacts. Thoseadaptationists who hold only that it isworthwhile to investigate organisms as thoughthey were artefacts and thoseanti-adaptationists who criticise simplisticdesign models have far more in common than thelabels attached to their positions mightsuggest. (shrink)

The article examines the role of natural kinds in semantic theorizing, which has largely been conducted in isolation from relevant work in science, metaphysics, and philosophy of science. We argue that the Kripke–Putnam account of natural kind terms, despite recent claims to the contrary, depends on a certain metaphysics of natural kinds; that the metaphysics usually assumed—micro-essentialism—is untenable even in a ‘placeholder’ version; and that the currently popular homeostatic property cluster theory of natural kinds is correct only to an extent (...) that fails to vindicate the Kripke–Putnam account. This undermines the metasemantics required for anti-descriptivist semantics. _1_ Introduction _2_ From Semantics to Metaphysics _3_ Metaphysics, Part I: The Demise of Micro-essentialism _3.1_ Original micro-essentialism _3.2_ Placeholder essentialism _4_ Metaphysics, Part II: Homeostatic Property Cluster Theory _5_ Prospects for Natural Kind Term Semantics. (shrink)

A long-running dispute concerns which adaptation-related explananda natural selection can be said to explain. At issue are explananda of the form: why a given individual organism has a given adaptation rather than that same individual having another trait. It is broadly agreed that one must be ready to back up a “no” answer with an appropriate theory of trans-world identity for individuals. I argue, against the conventional wisdom, that the same is true for a “yes” answer. My conclusion recasts the (...) landscape and opens the door to a potential resolution. (shrink)

There is a substantial literature on evolutionary debunking arguments (EDAs) in metaethics. According to these arguments, evolutionary explanations of our moral beliefs pose a significant problem for moral realism, specifically by committing the realist to an unattractive pessimism about the prospects of our having moral knowledge. In this paper, I argue that EDAs exploit an equivocation between two distinct readings of their central claim. One is plausibly true but has no epistemic relevance, and the other would have epistemic consequences for (...) realism, but is false. If I'm right, this undermines attempts to use evolutionary explanations to debunk belief in other domains too. (shrink)

Mainstream teleosemantics is the view that mental representation should be understood in terms of biological functions, which, in turn, should be understood in terms of selection processes. One of the traditional criticisms of teleosemantics is the problem of novel contents: how can teleosemantics explain our ability to represent properties that are evolutionarily novel? In response, some have argued that by generalizing the notion of a selection process to include phenomena such as operant conditioning, and the neural selection that underlies it, (...) we can resolve this problem. Here, we do four things: we develop this suggestion in a rigorous way through a simple example, we draw on recent neurobiological research to support its empirical plausibility, we defend the move from a host of objections in the literature, and we sketch how the picture can be extended to help us think about more complex “conceptual” representations and not just perceptual ones. (shrink)

Can selection explain why individuals have the traits they do? This question has generated significant controversy. I will argue that the debate encompasses two separable aspects, to detrimental effect: (1) the role of selection in explaining the origin and evolution of biological traits and (2) the implications this may have for explaining why individuals have the traits they do. (1) can be settled on the basis of evolutionary theory while (2) requires additional, extra-scientific assumptions. By making a distinction between traits (...) affected by a single factor and traits affected by multiple factors I show that selection can, under certain conditions, help explain the origin of traits. Resolving the first aspect enables us to critically assess the various incompatible and independent philosophical commitments made within the second aspect of the debate. (shrink)

Mental disorders are often thought to be harmful dysfunctions. Jerome Wakefield has argued that such dysfunctions should be understood as failures of naturally selected functions. This suggests, implicitly, that evolutionary biology and other Darwinian disciplines hold important information for anyone working on answering the philosophical question, ‘what is a mental disorder?’. In this article, the author argues that Darwinian theory is not only relevant to the understanding of the disrupted functions, but it also sheds light on the disruption itself, as (...) well as on the harm that attends the disruption. The arguments advanced here are partially based on the view that a core feature of Darwinism is that it stresses the environmental relativity of functions and dysfunctions. These arguments show a very close empirical connection between social judgments and dysfunctions , which is of interest for psychiatric theory. Philosophically, they lead to the conclusion that the concept of mental disorder is identical to the concept of mental dysfunction. Consequently, it is both misleading and redundant to conceptualize mental disorders as ‘harmful dysfunctions’, and not simply as ‘mental dysfunctions’. (shrink)

Mental disorders are often thought to be harmful dysfunctions. Jerome Wakefield has argued that such dysfunctions should be understood as failures of naturally selected functions. This suggests, implicitly, that evolutionary biology and other Darwinian disciplines hold important information for anyone working on answering the philosophical question, 'what is a mental disorder?'. In this article, the author argues that Darwinian theory is not only relevant to the understanding of the disrupted functions, but it also sheds light on the disruption itself, as (...) well as on the harm that attends the disruption. The arguments advanced here are partially based on the view that a core feature of Darwinism is that it stresses the environmental relativity of functions and dysfunctions. These arguments show a very close empirical connection between social judgments and dysfunctions, which is of interest for psychiatric theory. Philosophically, they lead to the conclusion that the concept of mental disorder is identical to the concept of mental dysfunction. Consequently, it is both misleading and redundant to conceptualize mental disorders as 'harmful dysfunctions', and not simply as 'mental dysfunctions'. (shrink)

What would my life have been like if I had been born more intelligent? Or taller? Or a member of the opposite sex? Or a non-biological being? It is plausible that some of these questions make sense, while others stretch the limits of sense making. In addressing questions of how I might have been, genetic essentialism is popular, but this article argues that genetic essentialism, and other versions of origin essentialism for organisms, must be rejected. It considers the prospects for (...) counterpart theory and shows how counterpart theory can be used to illuminate volitional accounts of identity as proposed by Harry Frankfurt. This enables one to make sense of claims that, say, being gay, or Deaf, or Black, can be essential to someone's identity. The discussion is then extended to show how it can be made applicable to the transworld identity theorist who denies that individuals possess essential properties. (shrink)

Formulations of the essential commitment of the etiological theory of functions have varied significantly, with some individual authors' formulations even varying from one place to another. The logical geography of these various formulations is different from what is standardly assumed; for they are not stylistic variants of the same essential commitment, but stylistic variants of two non-equivalent versions of the etiological theory. I distinguish these “strong” and “weak” versions of the etiological theory (which differ with respect to the role of (...) selection in their definitions of function), draw out their respective implications, and argue that the weak version is to be preferred to the strong. (shrink)

An influential argument due to Elliott Sober, subsequently strengthened by Denis Walsh and Joel Pust, moves from plausible premises to the bold conclusion that natural selection cannot explain the traits of individual organisms. If the argument were sound, the explanatory scope of selection would depend, surprisingly, on metaphysical considerations concerning origin essentialism. I show that the Sober-Walsh-Pust argument rests on a flawed counterfactual criterion for explanatory relevance. I further show that a more defensible criterion for explanatory relevance recently proposed by (...) Michael Strevens lends support to the view that natural selection can be relevant to the explanation of individual traits. (shrink)

This is the second of a two-part essay on the history of debates concerning the creativity of natural selection, from Darwin through the evolutionary synthesis and up to the present. In the first part, I focussed on the mid-late nineteenth century to the early twentieth, with special emphasis on early Darwinism and its critics, the self-styled “mutationists.” The second part focuses on the evolutionary synthesis and some of its critics, especially the “neutralists” and “neo-mutationists.” Like Stephen Gould, I consider the (...) creativity of natural selection to be a key component of what has traditionally counted as “Darwinism.” I argue that the creativity of natural selection is best understood in terms of selection initiating evolutionary change, and selection directing evolutionary change, for example by creating the variation that it subsequently acts upon. I consider the respects in which both of these claims sound non-Darwinian, even though they have long been understood by supporters and critics alike to be virtually constitutive of Darwinism. (shrink)

Ruth Millikan and others advocate theories which attempt to naturalize wide mental content (e.g. beliefs.

Darwin's theory of evolution by natural selection provided the first, and only, causal-mechanistic account of the existence of adaptations in nature. As such, it provided the first, and only, scientific alternative to the “argument from design”. That alone would account for its philosophical significance. But the theory also raises other philosophical questions not encountered in the study of the theories of physics. Unfortunately the concept of natural selection is intimately intertwined with the other basic concepts of evolutionary theory—such as the (...) concepts of fitness and adaptation —that are themselves philosophically controversial. Fortunately we can make considerable headway in getting clear on natural selection without solving all of those outstanding problems. (shrink)

The role of genetic relatedness in social evolution has recently come under critical attention. These arguments are here critically analyzed, both theoretically and empirically. It is argued that when the conceptual structure of the theory of natural selection is carefully taken into account, genetic relatedness can be seen to play an indispensable role in the evolution of both facultative and advanced eusociality. Although reviewing the empirical evidence concerning the evolution of eusociality reveals that relatedness does not play a role in (...) the initial appearance of helper phenotypes, this follows simply from the fact that natural selection – of which relatedness is a necessary component – does not play a causal role in the origin of any traits. Further, separating two logically distinct elements of causal explanation – necessity and sufficiency – explains why the debate lingers on: although relatedness plays a necessary role in the evolution of helping and advanced eusociality, relatedness alone is not sufficient for their appearance. Therefore, if the relatedness variable in a given data set is held at a uniformly high value, then it indeed may turn out that other factors occupy a more prominent role. However, this does not change the fact that high relatedness functions as a necessary background condition for the evolution of advanced eusociality. (shrink)

This dissertation starts with a concise overview of what philosophers of science have written about unification and its role in scientific explanation during the last 50 years to provide the reader with some background knowledge. In order to bring unification back into the picture, I have followed two strategies, resulting respectively in Parts I and II of this dissertation. In Part I the idea of unification is used to refine and enrich the dominant causalmechanist and causal-interventionist accounts of scientific explanation. (...) In this part of the dissertation I bracket the classical ideas about unification: deduction and derivation. I do grant, for the sake of argument, that explanations are causal and argue that unification is important from within this causalist perspective. In Part II I continue my strategy of digging into scientific practice to find cases of ontological unification. But here I distance myself from the dominant literature that all explanations must be causal. I will investigate whether explanatory unification is possible in non-causal explanations. Part III contains some further reflections and conclusions. I will formulate my primary results, and I will elaborate on their implications for thinking about unification and explanation. The different forms of ontological unification were quite diverse. This relates to the method I have used. Throughout this dissertation the types of unification that were discussed emerged from digging into scientific practice. This philosophy-of-science-practice approach steered me towards a pluralistic view on unification and on explanation. In this dissertation I do not try to develop a new model of explanation and compare it to existing models. The aim is to show that there are important types of explanatory practice which cannot be properly analyzed if we neglect unification as a desideratum for explanations. (shrink)