I call an experiment “crucial” when it makes possible a decisive choice between conflicting hypotheses. Joharmsen's selection for size and weight within pure lines of beans played a central role in the controversy over continuity or discontinuity in hereditary change, often known as the Biometrician-Mendelian controversy. The “crucial” effect of this experiment was not an instantaneous event, but an extended process of repeating similar experiments and discussing possible objections. It took years before Johannsen's claim about the (...) genetic stability of pure lines was accepted as conclusively demonstrated by the community of geneticists. The paper also argues that crucial experiments thus interpreted contradict certain ideas about the underdetermination of theories by facts and the theory-ladenness of facts which have been influential in recent history and sociology of science. The acceptance of stability in the pure lines did not rest on prior preference for continuity or discontinuity. And this fact permitted a final choice between the two theories. When such choice is characterized as “decisive” or “final”, this is not meant in an absolute philosophical sense. What we achive in these cases is highly reliable empirical knowledge. The philosophical possibility of drawing (almost) any conclusion in doubt should be distinguished from reasonable doubt in empirical science. (shrink)

Going back at least to Duhem, there is a tradition of thinking that crucial experiments are impossible in science. I analyse Duhem's arguments and show that they are based on the excessively strong assumption that only deductive reasoning is permissible in experimental science. This opens the possibility that some principle of inductive inference could provide a sufficient reason for preferring one among a group of hypotheses on the basis of an appropriately controlled experiment. To be sure, there are (...) analogues to Duhem's problems that pertain to inductive inference. Using a famous experiment from the history of molecular biology as an example, I show that an experimentalist version of inference to the best explanation (IBE) does a better job in handling these problems than other accounts of scientific inference. Furthermore, I introduce a concept of experimental mechanism and show that it can guide inferences from data within an IBE-based framework for induction. 1. Introduction2. Duhem on the Logic of Crucial Experiments3. ‘The Most Beautiful Experiment in Biology’4. Why Not Simple Elimination?5. Severe Testing6. An Experimentalist Version of IBE 6.1. Physiological and experimental mechanisms6.2. Explaining the data6.3. IBE and the problem of untested auxiliaries6.4. IBE-turtles all the way down7. Van Fraassen's ‘Bad Lot’ Argument8. IBE and Bayesianism9. Conclusions. (shrink)

The article analyses in detail the Meselson–Stahl experiment, identifying two novel difficulties for the crucial experiment account, namely, the fragility of the experimental results and the fact that the hypotheses under scrutiny were not mutually exclusive. The crucial experiment account is rejected in favour of an experimental-mechanistic account of the historical significance of the experiment, emphasizing that the experiment generated data about the biochemistry of DNA replication that is independent of the testing of (...) the semi-conservative, conservative, and dispersive hypotheses. _1_ Introduction _2_ The Meselson–Stahl Experiment _3_ Some Difficulties for the Crucial Experiment Account _3.1_ Additional experiments were required _3.2_ Simplicity considerations are unconvincing _3.3_ The fragility of the experimental results _3.4_ The problematic interpretation of falsifyng results _3.5_ Not all possible hypotheses considered or tested _3.6_ The tested hypotheses were not mutually exclusive _4_ The Historical and Scientific Significance of the Meselson–Stahl Experiment _4.1_ The challenge for the crucial experiment account _4.2_ A mechanistic perspective on the experiment _4.3_ The experimental design and its independence from theoretical speculations _4.4_ The advantages of a ‘bottom-up’ mechanistic account _5_ Conclusion. (shrink)

Although Duhem’s thesis that in physics crucial experiments are impossible contains some grains of truth in it, its effects have been greatly exaggerated. In this talk I argue against this and other associated theses by pointing out the various ways in which these theses can be curtailed. In the process of doing so, I examine a few recent attempts to overcome the problems posed by these theses and identify their strengths and weaknesses.

I defend the view that single experiments can provide a sufficient reason for preferring one among a group of hypotheses against the widely held belief that “crucial experiments” are impossible. My argument is based on the examination of a historical case from molecular biology, namely the Meselson-Stahl experiment. “The most beautiful experiment in biology”, as it is known, provided the first experimental evidence for the operation of a semi-conservative mechanism of DNA replication, as predicted by Watson and (...) Crick in 1953. I use a mechanistic account of explanation to show that this case is best construed as an inference to the best explanation (IBE). Furthermore, I show how such an account can deal with Duhem's well-known arguments against crucial experiments as well as Van Fraassen's “bad lot” argument against IBE. (shrink)

In the past few years there has been a turn towards evaluating the empirical foundation of epistemic contextualism using formal (rather than armchair) experimental methods. By-and-large, the results of these experiments have not supported the original motivation for epistemic contextualism. That is partly because experiments have only uncovered effects of changing context on knowledge ascriptions in limited experimental circumstances (when contrast is present, for example), and partly because existing experiments have not been designed to distinguish between contextualism and one of (...) its main competing theories, subject-sensitive invariantism. In this paper, we discuss how a particular, "third-person", experimental design is needed to provide evidence that would support contextualism over subject-sensitive invariantism. In spite of the theoretical significance of third-person knowledge ascriptions for debates surrounding contextualism, no formal experiments evaluating such ascriptions that assess contextualist claims have previously been conducted. In this paper, we conduct an experiment specifically designed to examine that central gap in contextualism’s empirical foundation. The results of our experiment provide crucial support for epistemic contextualism over subject-sensitive invariantism. (shrink)

This argument map presents Paul Loewi’s crucial experiment in which he showed that neural transmissions of signals are chemical in nature, not electrical, in form of an argumentation. The map can be used in science education to show how the formulation of hypotheses should be related to a corresponding determination of experimental designs.

In the second half of the eighteenth century a lively debate was going on in Germany about the nature of light. One important contribution to this discussion, namely a paper by Nicolas Béguelin, is studied in this article. In his essay, Béguelin compared the Newtonian emission theory of light and the wave theory of Leonhard Euler. Whereas others opted for one of the two theories by invoking arguments or authorities, Béguelin made a systematic search for experiments which he hoped would (...) settle the dispute. Two of these experiments were most original. The first, which Béguelin himself performed, concerned light rays grazing a glass surface. For several reasons it did not have the impact it deserved. The second one was a thought experiment which was meant to illustrate a major tenet of the wave theory, that is, the analogy between light and sound. An analysis is given of these two experiments, and it is shown that neither of them brought the debate to an end. (shrink)

I have previously argued that stem cell experiments cannot demonstrate that a single cell is a stem cell (Fagan 2013a, b). Laplane and others dispute this claim, citing experiments that identify stem cells at the singlecell level. This paper rebuts the counterexample, arguing that the alleged ‘crucial stem cell experiments’ do not measure self-renewal for a single cell, do not establish a single cell’s differentiation potential, and, if interpreted as providing results about single cells, fall into epistemic circularity. I (...) then discuss the source of the dispute, locating it in differences between philosophical and experimental perspectives. (shrink)

I have previously argued that stem cell experiments cannot demonstrate that a single cell is a stem cell. Laplane and others dispute this claim, citing experiments that identify stem cells at the single-cell level. This paper rebuts the counterexample, arguing that the alleged ‘crucial stem cell experiments’ do not measure self-renewal for a single cell, do not establish a single cell’s differentiation potential, and, if interpreted as providing results about single cells, fall into epistemic circularity. I then discuss the (...) source of the dispute, locating it in differences between philosophical and experimental perspectives. (shrink)

There is much evidence, both in humans and rodents, that while navigating males tend to use geometric information whereas females rely more on landmarks. The present work attempts to alter the geometry bias in female rats. In Experiment 1 three groups of female rats were trained in a triangular-shaped pool to find a hidden platform, whose location was defined in terms of two sources of information, a landmark outside the pool and a particular corner of the pool. On a (...) subsequent test trial with the triangular pool and no landmark, females with prior experience with two other pool shapes–with a kite-shaped pool and with a rectangular-shaped pool, were significantly more accurate than control rats without such prior experience. Rats with a short previous experience–with the rectangular-shaped pool only did not differ from Group NPE. These results suggest that the previous experience with different shaped-pools could counteract the geometry bias in female rats. Then, Experiment 2A directly compared the performance of LPE males and females of Experiment 1, although conducting several test trials. The differences between males and females disappeared in the three tests. Moreover, in a final test trial both males and females could identify the correct corner in an incomplete pool by its local, instead of global, properties. Finally, Experiment 2B compared the performance of NPE rats, males and females, of Experiment 1. On the test trial with the triangular pool and no landmark, males were significantly more accurate than females. The results are explained in the framework of selective attention. (shrink)

In this paper, I argue for a novel reading of Spinoza’s position in his exchangewith Boyle about Boyle’s experiment with nitre. Boyle claimed to have shownthrough experiments that nitre ceased to be nitre after heating. Spinozadisagreed and proposed the alternative hypothesis that nitre has changed itsstate and not its nature. Spinoza’s position was construed in the literature asrational scepticism denying that experiments can yield knowledge ofessences because all sensory experience is underdetermined and open tomultiple interpretations. I argue for an (...) alternative reading of Spinoza’sposition which focuses on Bacon’s notion of crucial instance. According tothis reading, Spinoza did not deny the possibility of knowing byexperimentation whether nitre has changed its nature, he asked for a crucialinstance, i.e. an experiment that would refute the hypothesis that nitre haschanged merely its state. Spinoza’s argumentative strategy shows that,contrary to the mainstream reading, the representational content of sensoryideas can be determined even if it does not represent the essence of theobject: we can know with absolute, rather than merely moral, certaintywhether nitre ceased to be nitre without knowing what nitre is. (shrink)

In several recent publications, Professor Adolf Grünbaum has inveighed against the conventionalism of writers like Einstein, Poincaré, Quine and especially Duhem. Specifically, Grünbaum has assailed the view that a single hypothesis can never be conclusively falsified. Grünbaum claims that the conventionalists’ insistence on the immunity of hypotheses from falsification is neither logically valid nor scientifically sound. Directing the weight of his argument against Duhem, Grünbaum launches a two-pronged attack. He insists, first, that conclusive falsifying experiments are possible, suggesting that Duhem's (...) denial of such experiments is a logical non-sequitur. He then proceeds to show that, more than being merely possible, crucial falsifying experiments have occurred in physics. I do not intend to make a logical point against Grünbaum's critique so much as an historical and exegetical one. Put briefly, I believe that he has misconstrued Duhem's views on falsifiability and that the logical blunder which he discusses should not be ascribed to Duhem, but rather to those who have made Duhem's conventionalism into the doctrine which Grünbaum attacks. Whether there are any writers who accept the view he imputes to Duhem, or whether he is exploiting “straw-men” to give weight to an otherwise trivial argument is an open question. For now, I simply want to suggest that his salvos are wrongly directed against Duhem. (shrink)

Maternal grandmothers play a key role in allomaternal care, directly caring for and provisioning their grandchildren as well as helping their daughters with household chores and productive labor. Previous studies have investigated these contributions across a broad time period, from infancy through toddlerhood. Here, we extend and refine the grandmothering literature to investigate the perinatal period as a critical window for grandmaternal contributions. We propose that mother-daughter co-residence during this period affords targeted grandmaternal effort during a period of heightened vulnerability (...) and appreciable impact. We conducted two focus groups and 37 semi-structured interviews with Himba women. Interviews focused on experiences from their first and, if applicable, their most recent birth and included information on social support, domains of teaching and learning, and infant feeding practices. Our qualitative findings reveal three domains in which grandmothers contribute: learning to mother, breastfeeding support, and postnatal health and well-being. We show that informational, emotional, and instrumental support provided to new mothers and their neonates during the perinatal period can aid in the establishment of the mother-infant bond, buffer maternal energy balance, and improve nutritional outcomes for infants. These findings demonstrate that the role of grandmother can be crucial, even when alloparenting is common and breastfeeding is frequent and highly visible. Situated within the broader anthropological and clinical literature, these findings substantiate the claim that humans have evolved in an adaptive sociocultural perinatal complex in which grandmothers provide significant contributions to the health and well-being of their reproductive-age daughters and grandchildren. (shrink)

Francis Bacon’s method of induction is often understood as a form of eliminative induction. The idea, on this interpretation, is to list the possible formal causes of a phenomenon and, by reference to a copious and reliable natural history, to falsify all of them but one. Whatever remains must be the formal cause. Bacon’s crucial instances are often seen as the crowning example of this method. In this article, I argue that this interpretation of crucial instances is mistaken, (...) and it has caused us to lose sight of why Bacon assigns crucial instances a special role in his quest for epistemic certainty about formal causes. If crucial instances are interpreted eliminatively, then they are subject to the two problems related to underdetermination raised by Duhem: (1) that it is impossible to be certain one has specified all of the possible alternatives and (2) that an experiment falsifies a whole theory, not just a single hypothesis in isolation. I show that Bacon anticipates and aims to dodge both of these problems by conceiving of crucial instances as working, in the ideal case, through direct affirmations that are supported by links to more foundational knowledge. (shrink)

: Our paper discusses the epistemic attitudes of particle physicists on the discovery of the Higgs boson at the Large Hadron Collider. It is based on questionnaires and interviews made shortly before and shortly after the discovery in 2012. We show, to begin with, that the discovery of a Standard Model Higgs boson was less expected than is sometimes assumed. Once the new particle was shown to have properties consistent with SM expectations – albeit with significant experimental uncertainties –, there (...) was a broad agreement that ‘a’ Higgs boson had been found. Physicists adopted a two-pronged strategy. On the one hand, they treated the particle as a SM Higgs boson and tried to establish its properties with higher precision; on the other hand, they searched for any hints of physics beyond the SM. This motivates our first philosophical thesis: the Higgs discovery, being of fundamental importance and establishing a new kind of particle, represented a crucial experiment if one interprets this notion in an appropriate sense. By embedding the LHC into the tradition of previous precision experiments and the experimental strategies thus established, underdetermination and confirmational holism are kept at bay. Second, our case study suggests that criteria of theory preference should be understood as epistemic and pragmatic values that have to be weighed in factual research practice. The Higgs discovery led to a shift from pragmatic to epistemic values as regards the mechanisms of electroweak symmetry breaking. Complex criteria, such as naturalness, combine epistemic and pragmatic different values, but are coherently applied by the community. (shrink)

Transfers of critically ill neonates are frequent phenomena. Even though parents’ participation is regarded as crucial in neonatal care, a transfer often means that parents and neonates are separated. A systematic review of the parents’ experiences of neonatal transfer is lacking. This paper describes a meta‐study addressing qualitative research about parents’ experiences of neonatal transfer. Through deconstruction and reflections of theories, methods, and empirical data, the aim was to achieve a deeper understanding of theoretical, empirical, contextual, historical, and methodological (...) issues of qualitative studies concerning parents’ experiences of neonatal transfer over the course of this meta‐study (2000–2017). Meta‐theory and meta‐method analyses showed that caring, transition, and family‐centered care were main theoretical frames applied and that interviewing with a small number of participants was the preferred data collection method. The meta‐data‐analysis showed that transfer was a scary, unfamiliar, and threatening experience for the parents; they were losing familiar context, were separated from their neonate, and could feel their parenthood disrupted. We identified ‘wavering and wandering’ as a metaphoric representation of the parents’ experiences. The findings add knowledge about meta‐study as an approach for comprehensive qualitative research and point at the value of meta‐theory and meta‐method analyses. (shrink)

Background: Suicidality is a life-and-death struggle in deep loneliness and psychological pain. There is a lack of knowledge about what could help the suicidal patients’ struggle for continued life. The aim of this study was to develop a deeper understanding of suicidal patients in the aftermath of suicidal attempts. The research question was ‘What resources in the person himself or herself and his or her surroundings are crucial in a suicidal crisis to maintaining the will to live and hope (...) for life’? Methodology: The study has a hermeneutic approach and an explorative design. Data were collected using semi-structured interviews with 10 participants: men and women 21–52 years of age. The context was two emergency psychiatric units and one crisis resolution team. Ethical considerations: The participants signed an informed consent before the interviews were conducted. Findings: This article presents three themes: becoming aware of the desire to live, an experience of connectedness and someone who cares. Discussion: The suicidal person’s awareness of wishes, dreams, hopes and will, but also of their feelings in the aftermath of the suicide attempt, seemed to play a crucial role in a suicidal crisis. Experiences of connectedness remind the person of the responsibility in his or her own life and in the lives of others and seemed to strengthen the urge to go on. Private and professional relationships seem to be crucial in stimulating the desire and hope to go on living. Conclusion: Becoming aware of the desire to live, being connected to others and experiencing someone who cares is necessary for life. Both private and professional networks seemed to be important resources that could remind the suicidal person of his or her own dignity as part of being human. (shrink)

This book offers a readable introduction to the main aspects of thought experimenting in philosophy and science. It presents the main options in understanding thought experiments, from empiricism to Platonism, and discusses their strengths and weaknesses. However, it also provides some original perspectives on the topic. Firstly, it provides a new definition and analysis of thought experimenting that brings it closer to laboratory experimenting. Secondly, it develops the author’s earlier theory of “mental modelling”, proposed some decades ago by him, and (...) some other researchers in the field as the crucial procedure in thought experimenting. The mental modelling approach links work with thought experimenting to cognitive science and to research on mental simulation which is a hot topic in present-day research. Thirdly, it proposes a principled way to respond to criticism of thought experimenting by “experimental philosophers” as they have been dominating the present-day debates. The response suggests a possible ameliorative, self-help project for thought experimenting. Finally, the book provides a way to systematize the history of important thought experiments in science and philosophy and thus connects, in an original way, the systematic investigation of experimenting to the historical work of famous thought experiments. It is of interest to scholars interested in history of ideas and philosophy of science. (shrink)

Metaphysical theories are often counter-intuitive. But they also often are strongly supported and motivated by intuitions. One way or another, the link between intuitions and metaphysics is a strong and important one, and there is hardly any metaphysical discussion where intuitions do not play a crucial role. In this article, I will be interested in a particular kind of such intuitions, namely those that come, at least partly, from experience. There seems to be a route from experience to metaphysics, (...) and this is the core of my interest here. In order to better understand such ‘arguments from experience’ and the kind of relationship there is between this type of intuitions and metaphysical theories, I shall examine four particular cases where a kind of experience-based intuition seems to motivate or support a metaphysical theory. At the end of the day, I shall argue that this route is a treacherous one, and that in all of the four cases I shall concentrate on, phenomenological considerations are in fact orthogonal to the allegedly ‘corresponding’ metaphysical claims. An anti-realist view of metaphysics will emerge. (shrink)

The article by Potter and Rif S. El-Mallakh read empathically, invokes a sense of fulfilment in their experiences, serving as inspiration for others to learn and practice ethics better. It describes their growth that has culminated to this sense of fulfilment and inspirational dignity. Crucial for this desirable growth has been, I want to highlight, their good investment in virtuous relationships and diligent processes. I also highlight from their article a potential conceptual restriction to growing in our learning and (...) practicing of ethics. That is, the restriction that occurs when blinded by too narrow a view on what ethics is about or where its emphasis is supposed to be. (shrink)

Contrary to assumptions that changes in brain networks are possible only during crucial periods of development, research in the past decade has supported the idea of a permanently plastic brain. Novel experience, altered afferent input due to environmental changes and learning new skills are now recognized as modulators of brain function and underlying neuroanatomic circuitry. Given findings in experiments with animals and the recent discovery of increases in gray and white matter in the adult human brain as a result (...) of learning, the old concept of cognitive reserve, that is the ability to reinforce brain volume in crucial areas and thus provide a greater threshold for age-dependent deficits, has been reinforced. The challenge we face is to unravel the exact nature of the dynamic structural alterations and, ultimately, to be able to use this knowledge for disease management. Understanding normative changes in brain structure that occur as a result of environmental changes and demands is pivotal to understanding the characteristic ability of the brain to adapt. (shrink)

Ethology brought some crucial insights and perspectives to the study of behavior, in particular the idea that behavior can be studied within a comparative-evolutionary framework by means of homologizing components of behavioral patterns and by causal analysis of behavior components and their integration. Early ethology is well-known for its extensive use of qualitative observations of animals under their natural conditions. These observations are combined with experiments that try to analyze behavioral patterns and establish specific claims about animal behavior. Nowadays, (...) there is still disagreement about the significance of observation and experiments and their relation. (shrink)

Context: The majority of contemporary enactivist work is influenced by the philosophical biology of Hans Jonas. Jonas credits all living organisms with experience that involves particular “existential” structures: nascent forms of concern for self-preservation and desire for objects and outcomes that promote well-being. We argue that Jonas’s attitude towards living systems involves a problematic anthropomorphism that threatens to place enactivism at odds with cognitive science, and undermine its legitimate aims to become a new paradigm for scientific investigation and understanding of (...) the mind. Problem: Enactivism needs to address the tension between its Jonasian influences and its aspirations to become a new paradigm for cognitive science. By relying on Jonasian phenomenology, contemporary enactivism obscures alternative ways in which phenomenology can be more smoothly integrated with cognitive science. Method: We outline the historical relationship between enactivism and phenomenology, and explain why anthropomorphism is problematic for a research program that aspires to become a new paradigm for cognitive science. We examine the roots of Jonas’s existential interpretation of biological facts, and describe how and why Jonas himself understood his project as founded on an anthropomorphic assumption that is incompatible with a crucial methodological assumption of scientific enquiry: the prohibition of unexplained natural purposes. We describe the way in which phenomenology can be integrated into Maturana’s autopoietic theory, and use this as an example of how an alternative, non-anthropomorphic science of the biological roots of cognition might proceed. Results: Our analysis reveals a crucial tension between Jonas’s influence on enactivism and enactivism’s paradigmatic aspirations. This suggests the possibility of, and need to investigate, other ways of integrating phenomenology with cognitive science that do not succumb to this tension. Implications: In light of this, enactivists should either eliminate the Jonasian inference from properties of our human experience to properties of the experience of all living organisms, or articulate an alternative conception of scientific enquiry that can tolerate the anthropomorphism this inference entails. The Maturanian view we present in the article’s final section constitutes a possible framework within which enactivist tools and concepts can be used to understand cognition and phenomenology, and that does not involve a problematic anthropomorphism. Constructivist content: Any constructivist approach that aims for integration with current scientific practice must either avoid the type of anthropomorphic inference on which Jonas bases his work, or specify a new conception of scientific enquiry that renders anthropomorphism unproblematic. (shrink)

Assuming that the qualities of immediate experience ('sentience') are the subjective aspect of the neurophysiological cerebral processes, And assuming that all behavior is ultimately susceptible to physical explanation, There are a number of ways in which mind-Body monism can be stated. But there are also a number of serious difficulties for a logically coherent formulation of the identity thesis of the mental and the physical.

... the topic of 'meaning' is the one topic discussed in philosophy in which there is literally nothing but 'theory' - literally nothing that can be labelled or even ridiculed as the 'common sense view'. Putnam, 'The Meaning of Meaning' This book explores some truths behind the truism that experimentation is a hallmark of scientific activity. Scientists' descriptions of nature result from two sorts of encounter: they interact with each other and with nature. Philosophy of science has, by and large, (...) failed to give an account of either sort of interaction. Philosophers typically imagine that scientists observe, theorize and experiment in order to produce general knowledge of natural laws, knowledge which can be applied to generate new theories and technologies. This view bifurcates the scientist's world into an empirical world of pre-articulate experience and know how and another world of talk, thought and argument. Most received philosophies of science focus so exclusively on the literary world of representations that they cannot begin to address the philosophical problems arising from the interaction of these worlds: empirical access as a source of knowledge, meaning and reference, and of course, realism. This has placed the epistemological burden entirely on the predictive role of experiment because, it is argued, testing predictions is all that could show that scientists' theorizing is constrained by nature. Here a purely literary approach contributes to its own demise. The epistemological significance of experiment turns out to be a theoretical matter: cruciality depends on argument, not experiment. (shrink)

Sometimes it is not us but those to whom we stand in special relations that face transformative choices: our friends, family, or beloved. A focus upon first-personal rational choice and agency has left crucial ethical questions regarding what we owe to those who face transformative choices largely unexplored. In this paper, I ask: under what conditions, if any, is it morally permissible to interfere with to try to prevent another from making a transformative choice? Some seemingly plausible answers to (...) this question fail precisely because they concern transformative experiences. I argue that we have a distinctive moral right to revelatory autonomy grounded in the value of autonomous self-making. If this right is outweighed then, I argue, interfering to prevent another making a transformative choice is permissible. This conditional answer lays the groundwork for a promising ethics of transformative experience. (shrink)

The nature of perception has long been a central question in philosophy. It is of crucial importance not just in the philosophy of mind, but also in epistemology, metaphysics, aesthetics, and the philosophy of science. The essays in this 1992 volume not only offer fresh answers to some of the traditional problems of perception, but also examine the subject in light of contemporary research on mental content. A substantial introduction locates the essays within the recent history of the subject, (...) and demonstrates the links between them. The Contents of Experience brings together some prominent philosophers in the field, and offers a major statement on a problem central to current philosophical thinking. Notable contributors include Christopher Peacocke, Brian O'Shaughnessy and Michael Tye. (shrink)