_Conservative Reductionism_ sets out a new theory of the relationship between physics and the special sciences within the framework of functionalism. It argues that it is wrong-headed to conceive an opposition between functional and physical properties and to build an anti-reductionist argument on multiple realization. By contrast, all properties that there are in the world, including the physical ones, are functional properties in the sense of being causal properties, and all true descriptions that the special sciences propose can in principle (...) be reduced to physical descriptions by means of functional reduction, despite multiple realization. The book develops arguments for from the metaphysics of properties and the philosophy of physics. These arguments lead to a conservative ontological reductionism. It then develops functional reduction into a fully-fledged, conservative theory reduction by means of introducing functional sub-types that are coextensive with physical types, illustrating that conservative reductionism by means of case studies from biology. (shrink)

After the discovery of the structure of DNA in 1953, scientists working in molecular biology embraced reductionism—the theory that all complex systems can be understood in terms of their components. Reductionism, however, has been widely resisted by both nonmolecular biologists and scientists working outside the field of biology. Many of these antireductionists, nevertheless, embrace the notion of physicalism—the idea that all biological processes are physical in nature. How, Alexander Rosenberg asks, can these self-proclaimed physicalists also be antireductionists? With (...) clarity and wit, Darwinian Reductionism navigates this difficult and seemingly intractable dualism with convincing analysis and timely evidence. In the spirit of the few distinguished biologists who accept reductionism—E. O. Wilson, Francis Crick, Jacques Monod, James Watson, and Richard Dawkins—Rosenberg provides a philosophically sophisticated defense of reductionism and applies it to molecular developmental biology and the theory of natural selection, ultimately proving that the physicalist must also be a reductionist. (shrink)

Causal reductionism is the widespread assumption that there is no room for additional causes once we have accounted for all elementary mechanisms within a system. Due to its intuitive appeal, causal reductionism is prevalent in neuroscience: once all neurons have been caused to fire or not to fire, it seems that causally there is nothing left to be accounted for. Here, we argue that these reductionist intuitions are based on an implicit, unexamined notion of causation that conflates causation (...) with prediction. By means of a simple model organism, we demonstrate that causal reductionism cannot provide a complete and coherent account of ‘what caused what’. To that end, we outline an explicit, operational approach to analyzing causal structures. (shrink)

Contrary to a widespread belief, this book establishes that ontological and epistemological reductionism stand or fall together.

Nonreductive physicalists have a causal exclusion problem. Given certain theses all physicalists accept, including psychophysical supervenience and the causal closure of the physical realm, it is difficult to see how irreducible mental phenomena could make a causal difference to the world. The upshot, according to those who push the problem, is that we must embrace reductive physicalism. Only then is mental causation saved. -/- Grant the argument, at least provisionally. Here our focus is the conditional question: What form should one's (...) reductionism take if it is motivated in part by the exclusion problem? Must one be a type identity theorist, or are alternative reductive views available, as Jaegwon Kim has suggested more than once? (shrink)

The practice of reductionism in science and philosophy includes attempts to essentialize human persons, which can lead to serious social problems. Reductionism is not necessary, as comparative philosophers and alternative-thinking scientists have shown.

Reductionists are those who take one theory or phenomenon to be reducible to some other theory or phenomenon. For example, a reductionist regarding mathematics might take any given mathematical theory to be reducible to logic or set theory. Or, a reductionist about biological entities like cells might take such entities to be reducible to collections of physico-chemical entities like atoms and molecules. The type of reductionism that is currently of most interest in metaphysics and philosophy of mind involves the (...) claim that all sciences are reducible to physics. This is usually taken to entail that all phenomena (including mental phenomena like consciousness) are identical to physical phenomena. The bulk of this article will discuss this latter understanding of reductionism. (shrink)

Richard Spencer-Smith; VII*—Reductionism and Emergent Properties, Proceedings of the Aristotelian Society, Volume 95, Issue 1, 1 June 1995, Pages 113–130, https.

Paulina Sliwa (2015) argues that knowing why p is necessary and sufficient for understanding why p. She tries to rebut recent attacks against the necessity and sufficiency claims, and explains the gradability of understanding why in terms of knowledge. I argue that her attempts do not succeed, but I indicate more promising ways to defend reductionism about understanding why throughout the discussion.

I argue that there are good reasons to deny both type-type and token-token mind-brain identity theories. Yet on the other hand there are compelling reasons for thinking that there is a causal basis for the mind. I argue that a path out of this impasse involves not only showing that criteria of individuation do not determine identity, but also that there are sound methodological reasons for thinking that the cause of intelligent behavior is a real natural kind. Finally, a commitment (...) to this methodology suggests both that these familiar anti-reductionist arguments fail to establish that identity is impossible and at the same time suggest that the preferred alternative will be some version of neutral monism. (shrink)

The present volume aims at giving a discussion ot the problems ot reductionism in contemporary life sciences. It contains six papers which deals with reduction/reductionism in different fields ot biological research. Also, the holistic perspective, 1. e. the systems view, is discussed in some ot the papers. The message ot this discussion Is that - whereas reductionism is indeed an important strategy - the systems approach is needed. It is argued by some ot the authors that organisms (...) are complex systems and not just heaps of molecules, 50 that the analytical method does not suffice. Recent developments in systems theory offer the possibility to install a more comprehensive view ot living systems what can be seen particularly in the field ot evolutionary biology. It is true that any organismic activity is molecular, this is to say that it is based on molecular mechanisms. But it is also true that the whole organism displays certain patterns ot behavior which are not just molecular. Any organism can be described as a system ot different levels ot organization different levels ot order and complexity - and it is important, theretore, to study all ot the organizational levels and to see their peculiarities. It should be obvious, however, that there is not one problem ot reduction/reductionism, but that there are many problems linked together and that these problems appear at different levels ot biological research and bio philosophical reflections. (shrink)

Kim’s causal exclusion argument purports to demonstrate that the non-reductive physicalist must treat mental properties (and macro-level properties in general) as causally inert. A number of authors have attempted to resist Kim’s conclusion by utilizing the conceptual resources of Woodward’s interventionist conception of causation. The viability of these responses has been challenged by Gebharter, who argues that the causal exclusion argument is vindicated by the theory of causal Bayesian networks (CBNs). Since the interventionist conception of causation relies crucially on CBNs (...) for its foundations, Gebharter’s argument appears to cast significant doubt on interventionism’s anti-reductionist credentials. In the present article, we both (1) demonstrate that Gebharter’s CBN-theoretic formulation of the exclusion argument relies on some unmotivated and philosophically significant assumptions (especially regarding the relationship between CBNs and the metaphysics of causal relevance), and (2) use Bayesian networks to develop a general theory of causal inference for multi-level systems that can serve as the foundation for an anti-reductionist interventionist account of causation.1. (shrink)

Methodological reductionists practice ‘wannabe reductionism’. They claim that one should pursue reductionism, but never propose how. I integrate two strains in prior work to do so. Three kinds of activities are pursued as “reductionist”. “Successional reduction” and inter-level mechanistic explanation are legitimate and powerful strategies. Eliminativism is generally ill-conceived. Specific problem-solving heuristics for constructing inter-level mechanistic explanations show why and when they can provide powerful and fruitful tools and insights, but sometimes lead to erroneous results. I show how (...) traditional metaphysical approaches fail to engage how science is done. The methods used do so, and support a pragmatic and non-eliminativist realism. (shrink)

This chapter investigates the prospects for an important position that falls under the "mere patterns" approach: what, for reasons that will emerge, the author calls"Humean reductionism" about laws of nature, a view championed perhaps most prominently by David Lewis. He reviews some of the most interesting arguments against this position from the literature, and adds some of his own that, he thinks, are more effective. The chapter considers how the best system account (BSA) would apply to the Newtonian particle (...) world. The BSA has been challenged in a wide variety of ways: it violates certain intuitions; It makes a hash out of the connection between laws on the one hand, and counterfactuals, explanation, and induction on the other. The author thinks that the problem he has raised‐challenging though he hopes it is, is really an occasion for the Humean reductionist to sharpen his position still further. (shrink)

While committed to the view that Buddhist Reductionism offers the best account of the Abhidharma distinction of the two truths, Siderits (2009) argues that Buddhist Reductionism has the surprising consequence of making itself inexpressible. This inexpressibility follows from the semantic insulation between conventional and ultimate discourses that Siderits argues is required in order to preserve classical logic for both types of discourse, avoiding contradiction and bivalence failure. I argue that inexpressibility is a problematic consequence that threatens to constitute (...) a reductio of Buddhist Reductionism. (shrink)

In previous work, I defend the following disparity between moral and epistemic facts: whereas moral facts are irreducibly normative, epistemic facts – facts such as that some subject is epistemically justified in believing something – are reducible to facts from some other domain (such as facts about probabilities). This moral-epistemic disparity is significant because it undercuts an important kind of argument for robust moral realism. My defense of epistemic reductionism and of the moral-epistemic disparity has been criticized by Richard (...) Rowland (2013) and by Terence Cuneo and Christos Kyriacou (forthcoming). This paper aims to rebut these criticisms and, more generally, to clarify and strengthen the case for epistemic reductionism and the moral-epistemic disparity. (shrink)

Reductionism’s approach brings together many of the most interesting questions today in philosophy and in science . It also presents a brief history of how reductionism has developed in Western philosophy and religion, with reference to Indian philosophy on certain issues.

While Derek Parfit is aware that his reductionism about persons is anticipated in early Buddhism and Abhidharma, he has not explored that tradition for any clues it might yield concerning the consequences of adopting the position. In this essay, the tradition is used to construct a taxonomy of possible views about persons, and then examine the meta-physical commitments that Buddhist reductionists claim are entailed by their view. While these turn out to be significant, it is argued here that this (...) is a price a reductionist should be prepared to pay. (shrink)

A contemporary analytic philosophy approach to science is discussed. It is pointed out that enthusiasm for language studies in philosophy has been recently grossly exaggerated. A role of experimental science as a source of "profound" questions about the essence of the world should be more appreciated. It is shown that the so-called common intuitions fail to capture the gist of current problems in science and can no longer lead us to faithful solutions. For instance, it is not easy to reconcile (...) with common intuitions a vision of the world as a set of latent potential possibilities which show up themselves only under certain conditions. Therefore, dynamic description of the world is proposed to treat both phenomena and various processes among them. In order to achieve this we ought to focus on fates of allegedly fundamental theories and on a strategy of making science. The latter is thoroughly discussed in this article. Furthermore, three types of reductionism are scrutinized and it leads us to the conclusion that our understanding of the world is more likely based on our ability to explain diversified phenomena than on our capacity to reduce them to the ostensibly fundamental models or theories. (shrink)

According to anti‐reductionism, audiences have a default (but defeasible) epistemic entitlement to accept observed testimony. This paper explores the prospects of arguing from this premise to a conclusion in ethics, to the effect that speakers enjoy a default (but defeasible) moral entitlement to expect to be trusted when they testify. After proposing what I regard as the best attempt to link the two, I conclude that any argument from the one to the other will depend on a strong epistemological (...) assumption that has not yet been discussed in this connection. (shrink)

This paper analyses the anti-reductionist argument from renormalisation group explanations of universality, and shows how it can be rebutted if one assumes that the explanation in question is captured by the counterfactual dependence account of explanation.

Consciousness, Reductionism and the Explanatory Gap: Investigations in Honor of Rudolf Carnap Content Type Journal Article Pages 1-3 DOI 10.1007/s11406-010-9272-7 Authors Leon de Bruin, Institut für Philosophie II, Ruhr-Universität Bochum, Universitätsstr. 150, 44801 Bochum, Germany Albert Newen, Institut für Philosophie II, Ruhr-Universität Bochum, Universitätsstr. 150, 44801 Bochum, Germany Journal Philosophia Online ISSN 1574-9274 Print ISSN 0048-3893 Journal Volume Volume 39 Journal Issue Volume 39, Number 1.

In this article, we analyse how researchers use the categories of race and ethnicity with reference to genetics and genomics. We show that there is still considerable conceptual “messiness” (despite the wide-ranging and popular debate on the subject) when it comes to the use of ethnoracial categories in genetics and genomics that among other things makes it difficult to properly compare and interpret research using ethnoracial categories, as well as draw conclusions from them. Finally, we briefly reconstruct some of the (...) biases of reductionism to which geneticists (as well as other researchers referring to genetic methods and explanations) are particularly exposed to, and we analyse the problem in the context of the biologization of ethnoracial categories. Our work constitutes a novel, in-depth contribution to the debate about reporting race and ethnicity in biomedical and health research. First, we reconstruct the theoretical background assumptions about racial ontology which researchers implicitly presume in their studies with the aid of a sample of recent papers published in medical journals about COVID-19. Secondly, we use the typology of the biases of reductionism to the problem of biologization of ethnoracial categories with reference to genetics and genomics. (shrink)

I consider a problem for functional reductionism, based on the following tension. Say that b is functionally reduced to a. On the one hand, a and b turn out to be identical, and identity is a symmetric relation. On the other hand, functional reductionism implies that a and b are asymmetrically related: if b is functionally reduced to a, then a is not functionally reduced to b. Thus, we ask: how can a and b be asymmetrically related if (...) they are the same thing? I propose a solution to this tension, by distinguishing between ontological levels and levels of description. (shrink)

Richard Spencer-Smith; VII*—Reductionism and Emergent Properties, Proceedings of the Aristotelian Society, Volume 95, Issue 1, 1 June 1995, Pages 113–130, https.

The case of very young children is a test case for the plausibility of reductionism about testimonial warrant. Reductionism requires reductive reasons, reductively justified and actively deployed for testimonial justification. Though nascent language-users enjoy warranted testimony based beliefs, they do not meet these three reductionist demands. This paper clearly formulates reductionism and the infant/child objection. Two rejoinders are discussed: an influential conceptual argument from Jennifer Lackey’s paper “Testimony and the Infant/Child Objection” and the growing empirical evidence from (...) developmental psychology on selective trust in children. Neither Lackey’s argument nor the empirical evidence vindicate reductionism. (shrink)

From the perspective of nonlinear science, it is argued that one may accept physicalism and reject substance dualism without being forced into reductionism. This permits a property dualism under which biological and mental phenomena may emerge from intricate positive feedback networks, involving many levels of both the biological and cognitive hierarchies.

Reductionism is a metaphysical thesis, a claim about explanations, and a research program. The metaphysical thesis reductionists advance (and antireductionists accept) is that all facts, including all biological facts, are fixed by the physical and chemical facts; there are no non-physical events, states, or processes, and so biological events, states and processes are “nothing but” physical ones. The research program can be framed as a methodological prescription which follows from the claim about explanations. Antireductionism does not dispute reductionism’s (...) metaphysical claim, but rejects the explanatory claim and so the methodological moral. To a first approximation what reductionists and antireductionists disagree about is whether explanations in functional biology can be or need to be explained by or completed or perhaps replaced by explanations in terms of molecular biology.i And this disagreement over the adequacy of explanations in functional biology drives a significant methodological disagreement with consequence for the research program of biology. (shrink)

Explanatory models in psychiatry reflect what clinicians deem valuable in rendering people's behavior intelligible and thus help guide treatment choices for mental illnesses. This article outlines some key scientific and ethical principles of clinical explanation in twenty-first century psychiatry. Recent work in philosophy of science, clinical psychiatry, and psychiatric ethics are critically reviewed in order to elucidate conceptual underpinnings of contemporary explanatory models. Many explanatory models in psychiatry are reductionistic or eclectic. The former restrict options for diagnostic and therapeutic paradigm (...) choice, while the latter lack a well-defined theoretical basis. These two methodological approaches stand in a dialectical relation to one another insofar as clinicians often move from one approach to its antithesis, ultimately seeking a synthesis of the two approaches that satisfies clinical needs. Pragmatic considerations can help to transcend the reductionism/eclecticism dialectic. In the absence of a completed science of mental disorders, psychiatrists must tolerate ambiguity and uncertainty as they strive to integrate diverse explanatory concepts in a rigorous and evidence-based fashion. A pragmatic explanatory model in clinical psychiatry must focus on favorable treatment outcomes for patients by respecting the pluralistic, participatory, and provisional nature of psychiatric explanation. (shrink)

In this paper, I clarify and defend a provocative hypothesis offered by Bernard Williams, namely, that modern people are much more likely to speak in terms of master-concepts like “good” or “right,” and correspondingly less likely to think and speak in the pluralistic terms favored by certain Ancient societies. By conducting a close reading of the Platonic dialogues Charmides and Laches, I show that the figure of Socrates plays a key historical role in this conceptual shift. Once we understand that (...) our narrow, reductionist focus on “thin” ethical concepts is a contingent historical development, we are, I claim, in a much better position to evaluate it. (shrink)

The paper raises some difficulties for the typical motivations behind set reductionism, the view that sets are reducible to entities identified independently of set theory.

Mark Twain said that, for people whose only tool is a hammer, everything looks like a nail. In Thinking about Technology, Joe Pitt's main tools appear to be those of the philosopher of science, so it is not surprising that he claims most problems of philosophy of technology are epistemic problems. As he puts it: 'The strategy here is straightforward. Philosophers of science have examined in detail a number of concepts integral to our understanding of what makes science what it (...) is. The bottom line is this: philosophical questions about technology are first and foremost questions about what we can know about a specific technology and its effects and in what that knowledge consists'. Although Pitt points out important disanalogies between scientific and technological knowledge, nevertheless he emphasizes that philosophy of technology is primarily epistemology. Pitt has stipulatively defined ethical and political analyses of technology as not part of philosophy and philosophy of technology. While claiming to assess the foundations of philosophy of technology, he has adopted a reductionist approach to his subject matter, one that ignores or denigrates the majority of work in philosophy of technology. Does Pitt's bold, reductionist move succeed? (shrink)

It has been suggested that Marr took the three levels he famously identifies to be independent. In this paper, we argue that Marr's view is more nuanced. Specifically, we show that the view explicitly articulated in his work attempts to integrate the levels, and in doing so results in Marr attacking both reductionism and vagueness. The result is a perspective in which both high-level information-processing constraints and low-level implementational constraints play mutually reinforcing and constraining roles. We discuss our recent (...) work on Spaun—currently the world's largest functional brain model—that demonstrates the positive impact of this kind of unifying integration of Marr's levels. We argue that this kind of integration avoids his concerns with both reductionism and vagueness. In short, we suggest that the methods behind Spaun can be used to satisfy Marr's explicit interest in combining high-level functional and detailed mechanistic explanations. (shrink)

Reductionist research programmes in psychology, and elsewhere, are typified by a number of research strategies and methodological assumptions. The current essay isolates and examines some typical reductionist assumptions as they have been embodied in psychological research. Through a brief examination of the use of lesion studies coupled with functional deficit analyses, it is argued that localizationist approaches to the study of brain function incorporate at least four interlocking hypotheses. Two of the hypotheses are examined in detail. It is urged that (...) neither is warranted, and there is reason to think each is suspect. (shrink)

Martha Nussbaum proposes a universal list of human capabilities as the basis for fundamental political principles. She claims that the list, in an Aristotelian spirit, might be justified by an ongoing inquiry into valuable human functionings for the good life. Here I argue that the attractiveness of Nussbaum’s theory crucially depends on the philosophical possibility of a non-reductionist understanding of naturalism and on resolving the tensions between ethical and political aspects of the role of capabilities. Through a comparison of Nussbaum’s (...) approach with those of Aristotle and (less familiarly) Hume, I try to show that in these alternative versions we find valuable resources for the kind of non-reductionist model which might, in line with Nussbaum’s own objectives, provide the basis for a capabilities-based critique of dominant modes of normative theorizing and their influence in public discourse. (shrink)

Reductionism concerns a set of ontological and epistemological claims, and methodological strictures based on them, about the relationship between two different scientific domains. The critical assumption is that one of these domains is privileged over the other in the sense that the concepts, rules, laws, and other elements of the privileged domain can be used to specify, constitute, or account for those of the other “reduced” domain. This specification often consists of explanation, such that the “reducing” domain is epistemically (...) privileged over the reduced one. Explanations of this type are “reductionist” (or, are “reductions”) and reductionism is then the thesis that such explanations will always be forthcoming or at least are possible in principle. Reductionism is most plausible if the entities of the reduced domain can be interpreted as arising from (e.g., as aggregates of) entities of the reduced domain. This ontological claim is controversial but motivates many reductionist theses and associated scientific research programs. Thus, epistemological and ontological claims about reductionism have the methodological implication that they should govern and guide scientific research. When such research proves to be fruitless over a period of time, the associated reductionist claims themselves become suspect. Although issues connected with reductionism arise in the physical and social sciences, most attention to reductionism in philosophy of science over the last few decades has focused on the biological sciences, especially after the advent of molecular biology made it plausible to believe that biological phenomena can be uniformly explained (in detail) from their physical basis. However, the program of finding such explanations has a long philosophical history often couched in terms of seeking “mechanical,” “mechanistic,” or “materialistic” explanations. The contrast here is with traditional vitalism and various forms of teleology and holism. (shrink)

P. Kitcher's unification theory of explanation appears to endorse a reductionistic view of scientific explanation that is inconsistant with scientific practice. In this paper, I argue that this appearance is illusory. The existence of multiply realizable generalizations enable the unification theory to also count many high-level accounts as explanatory.

With the advent of the Human Genome Project there have been many claims for the genetic origins of complex human behavior including insanity, criminality, and intelligence. But what does it really mean to call something 'genetic'? This is the fundamental question that Sahotra Sarkar's book addresses. The author analyses the nature of reductionism in classical and molecular genetics. He shows that there are two radically different kinds of reductionist explanation: genetic reduction (as found in classical genetics) and physical reduction (...) (found in molecular genetics). This important book clarifies the meaning of the term 'genetic', shows how molecular studies have affected genetics, and provides the philosophical background necessary to understand the debates over the Human Genome Project. It will be of particular interest to professionals and students in the philosophy of science, the history of science, and the social studies of science, medicine, and technology. (shrink)

The scope and nature of reductionist explanation in quantum physics is analyzed, with special attention being paid to the situation in quantum physics.

In this Article I argue that the reductionism of global models of constitutional rights is problematic. Despite how they are labelled, these theories are typically modelled on the domestic constitutional law of an exclusive group of Western countries. The criteria for selecting these countries are not usually clearly or satisfactorily articulated. They then go on to present a simplistic version of the domestic constitutional law of the countries they are describing. The combined effect of these analytic moves raises questions (...) about what is lost in the process, and in particular, whether these frameworks allow for adequate recognition of the claims of those seeking – and achieving – social change within a constitutional democracy. Drawing on insights from critical legal studies, and in particular scholars who seek the decolonization of constitutional law, I argue that the utility of global theories of constitutional rights depends on their ability to recognize and give voice to the forces of social change. Otherwise, they risk being descriptively inaccurate and even damaging to the broader causes they seek to advance. (shrink)

A common reductionist assumption is that macro-scale behaviors can be described "bottom-up" if only sufficient details about lower-scale processes are available. The view that an "ideal" or "fundamental" physics would be sufficient to explain all macro-scale phenomena has been met with criticism from philosophers of biology. Specifically, scholars have pointed to the impossibility of deducing biological explanations from physical ones, and to the irreducible nature of distinctively biological processes such as gene regulation and evolution. This paper takes a step back (...) in asking whether bottom-up modeling is feasible even when modeling simple physical systems across scales. By comparing examples of multi-scale modeling in physics and biology, we argue that the “tyranny of scales” problem presents a challenge to reductive explanations in both physics and biology. The problem refers to the scale-dependency of physical and biological behaviors that forces researchers to combine different models relying on different scale-specific mathematical strategies and boundary conditions. Analyzing the ways in which different models are combined in multi-scale modeling also has implications for the relation between physics and biology. Contrary to the assumption that physical science approaches provide reductive explanations in biology, we exemplify how inputs from physics often reveal the importance of macro-scale models and explanations. We illustrate this through an examination of the role of biomechanics modeling in developmental biology. In such contexts, the relation between models at different scales and from different disciplines is neither reductive nor completely autonomous, but interdependent. (shrink)

Like most domains of science, the study of the mind has been tackled at many scales of analysis, from the behavior of large groups of people, to the diffusion of ions across cellular membranes. At each of these scales, researchers often believe that the critical phenomena of interest, and the most powerful explanatory constructs and mechanisms, reside at their scale of analysis, with finer scales argued to be incapable of predicting the interesting phenomena, while coarser scales are purported to miss (...) critical mechanistic subtleties. Here we argue by analogy that, for better or worse, researchers at all scales are correct: phenomena at each scale of analysis are intractable from other scales; thus, while reductionism is a useful scientific goal, it will not obviate the need for macroscopic research, constructs, and formalisms. (shrink)

The study of mental illness by the methods of molecular genetics is still in its infancy, but the use of genetic markers in psychiatry may potentially lead to a Virchowian revolution in the conception of mental illness. Genetic markers may define novel clusters of patients having diverse clinical presentations but sharing a common genetic and mechanistic basis. Such clusters may differ radically from the conventional classification schemes of psychiatric illness. However, the reduction of even relatively simple Mendelian phenomena to molecular (...) genetics has been shown to be a surprisingly complex and problematic enterprise. Mental illnesses exist at many levels of including social, environmental, and developmental interactions. Reductionistic shifts in the classification of such a disease entity will have to address the interlevel dynamics that take place within the structure of theories of mental illness. The question of how molecular analysis of psychiatric disease will impact on the structure of existing theories and classification systems is the central topic of this paper. (shrink)