Conceptual engineering is commonly characterized as the method for assessing and improving our representational devices. Little has been said, however, on how best to construe these representational devices—in other words, on what conceptual engineering should be all about. This paper tackles this problem with a basic strategy: First, by presenting a taxonomy of the different possible subject matters for conceptual engineering; then, by comparatively assessing them and selecting the most conducive one with a view to making conceptual engineering an actionable (...) method, that is, a method that can be applied effectively and consistently to specific case studies. The outcome is that conceptual engineering should be all about concepts on pain of pragmatic inconsistencies otherwise. (shrink)

This is the introduction to the Special Issue ‘Foundational Issues in Conceptual Engineering’. The issue contains contributions by James Andow, Delia Belleri, David Chalmers, Catarina Dutilh Novaes, Eugen Fischer, Viktoria Knoll, Edouard Machery and Amie Thomasson. We, the editors, provide a brief introduction to the main topics of the issue and then summarize its contributions.

This paper discusses the logical space of alternative conceptual engineering projects, with a specific focus on (1) the processes, (2) the targets and goals, and (3) the methods of such projects. We present an overview of how these three aspects interact in the contemporary literature and discuss those alternative projects that have yet to be explored based on our suggested typology. We show how choices about each element in a conceptual engineering project constrain the possibilities for the others, thereby giving (...) rise to distinct groupings of possible projects under the banner of conceptual engineering. We conclude with a critical reflection on the potential ethical issues that arise as a result of effectively putting conceptual engineering into practice. (shrink)

Conceptual engineering means to provide a method to assess and improve our concepts working as cognitive devices. But conceptual engineering still lacks an account of what concepts are (as cognitive devices) and of what engineering is (in the case of cognition). And without such prior understanding of its subject matter, or so it is claimed here, conceptual engineering is bound to remain useless, merely operating as a piecemeal approach, with no overall grip on its target domain. The purpose of this (...) programmatic paper is to overcome this knowledge gap by providing some guidelines for developing the theories of concepts and of cognition that will ground the systematic unified framework needed to effectively implement conceptual engineering as a widely applicable method for the cognitive optimization of our conceptual devices. (shrink)

Conceptual engineering is the method for assessing and improving our concepts. However, little has been written about how best to conceive of concepts for the purposes of conceptual engineering. In this paper, I aim to fill this foundational gap, proceeding in three main steps: First, I propose a methodological framework for evaluating the conduciveness of a given concept of concept for conceptual engineering. Then, I develop a typology that contrasts two competing concepts of concept that can be used in conceptual (...) engineering — namely, the philosophical and psychological ones. Finally, I evaluate these two concepts of concept using the proposed methodological framework and I show that, when it comes to making conceptual engineering an actionable method, the psychological concept of concept outclasses its philosophical counterpart on all counts. This provides a baseline from which the concept of concept can be further improved for the purposes of conceptual engineering. (shrink)

Conceptual engineering is the method for assessing and improving our concepts. Some have recently claimed that the implementation of such method in the form of ameliorative projects is truth-driven and should thus be epistemically constrained, ultimately at least (Simion 2018; cf. Podosky 2018). This paper challenges that claim on the assumption of a social constructionist analysis of ideologies, and provides an alternative, pragmatic and cognitive framework for determining the legitimacy of ameliorative conceptual projects overall. The upshot is that one should (...) not ameliorate for the sake of truth or knowledge, in the case of ideologies—at least, not primarily. (shrink)

Conceptual engineering is the method for assessing and improving our representational devices. On its ‘broad-spectrum’ version, it is expected to be appropriately applicable to any of our representation-involving cognitive activities, with major consequences for our whole cognitive life. This paper is about the theoretical foundations of conceptual engineering thus characterised. With a view to ensuring the actionability of conceptual engineering as a broad-spectrum method, it addresses the issue of how best to construe the subject matter of conceptual engineering and successively (...) defends the theses that conceptual engineering should be: (i) About concepts, (ii) psychologically theorised, (iii) as multiply realised functional kinds. Thereby, I claim to theoretically secure and justify the maximum scope, flexibility, and impact for the method of conceptual engineering on our representational devices in our whole cognitive life—in other words, a broad-spectrum version of conceptual engineering. (shrink)

Conceptual engineering is the method for assessing and improving our representational devices. On its ‘broad‐spectrum’ version, it is expected to be appropriately applicable to any of our representation‐involving cognitive activities, with major consequences for our whole cognitive life. This paper is about the theoretical foundations of conceptual engineering thus characterised. With a view to ensuring the actionability of conceptual engineering as a broad‐spectrum method, it addresses the issue of how best to construe the subject matter of conceptual engineering and successively (...) defends the theses that conceptual engineering should be: (i) About concepts, (ii) psychologically theorised, (iii) as multiply realised functional kinds. Thereby, I claim to theoretically secure and justify the maximum scope, flexibility, and impact for the method of conceptual engineering on our representational devices in our whole cognitive life—in other words, a broad‐spectrum version of conceptual engineering. (shrink)

Ratio, Volume 34, Issue 4, Page 286-302, December 2021.

Au terme des Prolégomènes, Husserl formule son idée de la logique pure en la structurant sur deux niveaux: l'un, supérieur, de la logique formelle fondé transcendantalement et d'un point de vue épistémologique par l'autre, inférieur, d'une morphologie des catégories. Seul le second de ces deux niveaux est traité dans les Recherches logiques, tandis que les travaux théoriques en logique formelle menés par Husserl à la même époque en paraissent plutôt indépendants. Cet article est consacré à ces travaux tels que recueillis (...) dans les appendices VI-X du volume 12 des Husserliana. Mettant en évidence la théorie de la signification qui les sous-tend par le biais d'une analyse de la question dite de l'extension des systèmes d'axiomes et de sa résolution au moyen d'une notion de complétude, son objectif est d'expliciter les modalités de l'intégration de la logique formelle dans l'idée husserlienne de la logique pure au tournant du xx siècle.When formulating his idea of pure logic in the Prole.. (shrink)

The purpose of this paper is to provide a unitary typology for the incompatibilities of meanings at stake on different levels of Husserlian pure logic—namely, between systems of axioms and pure morphology of meanings; I show that they perfectly match by converging on the notion of Widersinn.

Intentionality may be dealt with in two different ways: either ontologically, as an ordinary relation to some extraordinary objects, or epistemologically, as an extraordinary relation to some ordinary objects. This paper endorses the epistemological view in order to provide a model of semiotic intentionality defined as the meaning-and-cognizing process that constitutes to power of the mind to be about something on the basis of a semiotic system. After a short introduction that presents the components of semiotic intentionality (viz. sign, act, (...) content, referent) along with their division into an intending and a fulfilling side (Sect. 1), the first main part of the paper analyzes semiotic intentionality at its primary level (a.k.a. 'concrete intentionality') as a real and subjective relation between meaning-intending and meaning-fulfilling acts grounded in the manipulation of some semiotic system (Sect. 2). Then, building on such concrete intentionality, the second main part of the paper analyzes semiotic intentionality at its secondary level (a.k.a. 'abstract intentionality') as an ideal and objective relation between intentional and fulfillment contents, which in turn: (i) proceed from an abstraction performed on the intending and fulfilling acts, respectively, and (ii) retroactively categorize the intending and fulfilling acts, respectively (Sect. 3). Finally, from this combination of an act-based conception of content with a presentationalist account of intentionality, the conclusion of this paper produces the intended model of semiotic intentionality in such a way that knowledge and truth are then respectively defined in it as the subjective correspondence between the two acts of concrete intentionality and as the objective correspondence between the two contents of abstract intentionality (Sect. 4). (shrink)

As a multi-layered theory of the foundations of “‘mathematicizing’ logic”, Husserlian pure logic is stratified on three levels (sub-theoretical, theoretical, meta-theoretical), which are then themselves transversally split in two sides (apophantic and ontological). This paper investigates how symbolic knowledge works in this framework—viz. in terms of ‘How can the subjective operating with symbols be justified in the process of obtaining objective contents of knowledge?’ To do so, it innovates in showing how Husserl’s theory of semiotic intentionality provides the epistemological-transcendental foundation (...) for the syntactic-semantic correspondence of the meaning relationship that is operative at the kernel of pure logic—i.e. on the theoretical level, between systems of axioms and formal manifolds. And thereby, it bridges the gap between the two volumes of the first edition of the Logical Investigations (namely, the Prolegomena and the six Investigations). (shrink)

Cet article a pour objet l’analyse de trois types de théorisations de la signification basées sur un modèle binaire du signe. Celles de Frege, Husserl et Saussure. Relevant d’un même paradigme, les deux premières sont confrontées en tant que s’y développent deux conceptions opposées de la signification – extensionnelle chez Frege, intensionnelle chez Husserl – contribuant à la mise en place, selon des perspectives opposées, de la dualisation de la syntaxe et de la sémantique. Relativement à cette conséquence, leur paradigme (...) est ensuite opposé à celui de la sémiologie structurale de Saussure dans laquelle l’interaction de la syntaxe et de la sémantique est internalisée au niveau du système qu’intègrent les signes comme éléments. De sorte que ce que l’on vise au terme de cet article, c’est à mettre au jour une explication possible de la raison de la divergence entre deux types de conceptions de la sémantique qui organiseront le développement de courants concurrents tout au long de l’histoire de la linguistique du 20e siècle, l’une formelle et mathématisée, l’autre structurale. (shrink)

This paper deals with Husserl’s idea of pure logic as it is coined in the Logical Investigations. First, it exposes the formation of pure logic around a conception of completeness ; then, it presents intentionality as the keystone of such a structuring ; and finally, it provides a systematic reconstruction of pure logic from the semiotic standpoint of intentionality. In this way, it establishes Husserlian pure logic as a phenomenological epistemology of mathematical logic.

The establishment of Mexico's National Bioethics Commission (Comisión Nacional de Bioética), in 1992, was conceived within the context of a global movement aimed at raising awareness of the ethical implications of technological and scientific development, especially in biomedicine. In 2005, a new decree put the commission under the scope of the Secretariat of Health and granted it technical and operational autonomy, allowing it to become a regulatory agency aimed at promoting a culture of bioethics, encouraging reflection on human health, and (...) developing guidelines for health care, research, and education, through a global, secular, and democratic perspective. The commission became the leading actor in the strategy for institutionalizing bioethics in Mexico after reforms to the country's General Health Act in 2011, which required that public, social assistance, or private health care facilities establish a hospital bioethics committee to address bioethical dilemmas or issues and, when relevant, a research ethics committee to address research with human subjects. This assignment has shifted the focus of the activities and goals of the National Bioethics Commission toward establishing these committees in line with current regulations and developing mechanisms to ensure that they operate with the highest standards of ethical conduct, performance, and accountability. (shrink)

The precarious rights of senior citizens, especially those who are highly educated and who are expected to counsel and guide the younger generations, has stimulated the creation internationally of advocacy associations and opinion leader groups. The strength of these groups, however, varies from country to country. In some countries, they are supported and are the focus of intense interest; in others, they are practically ignored. For this is reason we believe that the creation of a network of all these associations (...) is essential. The proposed network would act as a support for the already-existing policies of the United Nations’ High Commission for Human Rights, of independent experts, and of the Global Alliance for the Rights of Older People. All three have long ago recommended the creation of a recognized instrument for uniting presently scattered efforts. The proposed network, therefore, will seek to promote the international exchange of relevant expertise, and it will reinforce the commitments and actions that single countries are currently taking to meet these objectives. For example, informative public events can be organised to promote particular support initiatives and to provide an opportunity for new members of the network to be presented. The network will promote health for senior citizens, disease prevention, senior mobility, safe free time for seniors, alimentary education, protection against new risks and dangers, as well as equity in the services necessary for seniors to adopt new information and communication technologies. In the case of retired academic members, the network will promote equality with respect to continuing use of digital technologies (particularly email), continuing access to research libraries, and the guaranteed ability for seniors to fund their own research programs and to deliver free seminars. (shrink)

This volume has 41 chapters written to honor the 100th birthday of Mario Bunge. It celebrates the work of this influential Argentine/Canadian physicist and philosopher. Contributions show the value of Bunge’s science-informed philosophy and his systematic approach to philosophical problems. The chapters explore the exceptionally wide spectrum of Bunge’s contributions to: metaphysics, methodology and philosophy of science, philosophy of mathematics, philosophy of physics, philosophy of psychology, philosophy of social science, philosophy of biology, philosophy of technology, moral philosophy, social and political (...) philosophy, medical philosophy, and education. The contributors include scholars from 16 countries. Bunge combines ontological realism with epistemological fallibilism. He believes that science provides the best and most warranted knowledge of the natural and social world, and that such knowledge is the only sound basis for moral decision making and social and political reform. Bunge argues for the unity of knowledge. In his eyes, science and philosophy constitute a fruitful and necessary partnership. Readers will discover the wisdom of this approach and will gain insight into the utility of cross-disciplinary scholarship. This anthology will appeal to researchers, students, and teachers in philosophy of science, social science, and liberal education programmes. 1. Introduction Section I. An Academic Vocation Section II. Philosophy Section III. Physics and Philosophy of Physics Section IV. Cognitive Science and Philosophy of Mind Section V. Sociology and Social Theory Section VI. Ethics and Political Philosophy Section VII. Biology and Philosophy of Biology Section VIII. Mathematics Section IX. Education Section X. Varia Section XI. Bibliography. (shrink)

Due to the difficulty in solving combinatorial optimization problems, it is necessary to improve the performance of the algorithms by improving techniques to deal with complex optimizations. This research addresses the metaheuristics of marriage in honey-bees optimization based on the behavior of bees. The current study proposes a technique for solving combinatorial optimization problems within proper computation times. The purpose of this study focuses on the travelling salesperson problem and the application of chaotic methods in important sections of the MBO (...) metaheuristic. Three experiments were conducted to measure the efficiency and quality of the solutions: MBO with chaos to generate initial solutions ; MBO with chaos in the workers ; and MBO with chaos to generate initial solutions and the workers. The application of chaotic functions in MBO was significantly better at solving the travelling salesperson problem. (shrink)

A través de una reconstrucción de la evolución de su pensamiento, en este artículo se estudia la utilización de infinitesimales por parte de Newton. Se distingue entre dos concepciones sucesivas de lo que denominó momento. A la primera de estas entidades la caracterizó como un infinitesimal, pero a la segunda (un indivisible generador de magnitudes finitas, que interviene en su método de las primeras y últimas razones) no la consideró como tal. Se entiende así su manifestación de rechazo a los (...) infinitesimales, formulada en una segunda etapa, y se ve que las dudas arrojadas por algunos investigadores sobre la veracidad de tal manifestación se deben a una determinada interpretación de esta última concepción de momento.This paper discusses Newton’s recourse to infinitesimals through the reconstruction of the evolution of his thought. Two successive concepts of what he termed “moment” are told apart. The first of those entities was characterized by him as an infinitesimal, while the second -an indivisible generating finite magnitudes, present in his method of first and last reasons- was not considered such an entity. This move makes understandable his express rejection of infinitesimals in the second stage, and exposes the doubts of some scholars about the sincerity of Newton’s rejection as due to a peculiar interpretation of his last concept of “moment”. (shrink)

ABSTRACT The book reviewed here advances a fregean theory of reference able to stand up to Kripekean objections to descriptivism. It also claims that fictions are an invitation to imagine situations or pretending assertions and, in spite of it, fictions are objects of knowledge too, since they can refer to reality and we refer to fictional objects. In this review I present a summary of García-Carpintero's ideas and outline some objections to them.

A través de una reconstrucción de la evolución de su pensamiento, en este artículo se estudia la utilización de infinitesimales por parte de Newton. Se distingue entre dos concepciones sucesivas de lo que denominó momento. A la primera de estas entidades la caracterizó como un infinitesimal, pero a la segunda (un indivisible generador de magnitudes finitas, que interviene en su método de las primeras y últimas razones) no la consideró corno tal. Se entiende así su manifestación de rechazo a los (...) infinitesimales, formulada en una segunda etapa, y se ve que las dudas arrojadas por algunos investigadores sobre la veracidad de tal manifestación se deben a una determinada interpretación de esta última concepción de momento. (shrink)

The aim of this paper is to offer an alternative explanation to the notorious similitude detected in two ancient treatises on logic, namely, the Liber Peri Hermeneias, attributed to Apuleius of Madaura, and De syllogismo categorico, written by Boethius. Both were enormously authoritative in posterity. I argue that their similitude is due to the presence of an internal division of categorical propositions that Boethius gives in full in his De syllogismo categoricos, and repeats with extensions in his Introductio ad syllogismos (...) categorico. The division outlines the three main parts of the theory: opposition, conversion and syllogism. This leads us to argue that similarity and correspondence of these two ancient logical treatises can be sufficiently explained from this resource, and insufficiently explained by a certain common literary source, which was proposed by Isaac, without clarifying some important dissimilarities and divergences contained in these treatises. Also, our hypothesis does not need to suppose, as Sullivan, that Boethius borrowed from Apuleius. (shrink)

El objetivo de este artículo es el de señalar las implicaciones del concepto de deporte a través del materialismo filosófico de Gustavo Bueno en su obra Ensayo de una definición filosófica de la Idea de Deporte. Desde esta perspectiva, Bueno llega a la conclusión de que no hay una idea unívoca de deporte, sino que nos encontramos ante un concepto sobre el que se han depositado diversas acepciones según el objetivo físico, político, social o religioso atribuido al deporte. Esta (...) diversidad conceptual habilita al docente de Educación Física a utilizar el deporte como un medio pedagógico encajándolo de diferentes formas en su planificación. La principal conclusión es que el deporte puede ser utilizado no solo desde la perspectiva centrada en la práctica del deporte en sí, con sus reglas y movimientos, o teniendo solo como objetivo la actividad física, sino que puede utilizarse con relación a otros ámbitos de la educación física como la expresión corporal o los deportes populares. Con relación al estado de Ecuador, el currículum de Educación Física genera espacios para pensar en la Educación Física desde la interdisciplinariedad de sus ámbitos y no solo desde lo estrictamente deportivo. (shrink)

This paper employs network theory, mining data and bibliometric analysis when mapping the scientific contribution of Nobel Prize candidate; Manuel Sandoval Vallarta, the first and most renowned Mexican physicist and important figure in Latin American science. Vallarta died in 1977, and the existing literature is about his life and contributions to science but not about how those are still valuable today. This paper is the first to highlight, with mapping tools, that his contributions are relevant to the international community (...) of cosmic rays, quantum mechanics and relativity. These tools delivered three findings: Identify how he built his own field of study, same as universal knowledge. Unveil that the backward and forward Vallarta citations follow a scale-free network distribution. Determine social factors that benefited or affected his scientific activities—such as World War II interrupting Vallarta’s successful productivity at Massachusetts Institute of Technology. Furthermore, this study confirmed the interdisciplinary nature of the mapping studies of the scientist's contributions using scientometric tools. As a result, several interesting questions arose throughout our research, some of which were answered from the history and philosophy of science. However, others need to be analyzed by experts in the fields of Vallarta. Mapping research sends an invitation to interdisciplinary dialogue/research between experts in different areas of study to better understand the process of knowledge production both, individual and collective. (shrink)

This paper continues a debate on the normative limits of conceptual engineering. In particular, it responds to Manuel Gustavo Isaac’s (2021) claim, in response to Simion (2018a) and Podosky (2018), but in particular Podosky, that cognitive efficacy, rather than truth and knowledge, should be the normative standard by which we assess the legitimacy of a conceptual engineering project – at least for ideological concepts. I argue Isaac has not done enough to show us that truth and (...) knowledge are insignificant for the conceptual engineering of ideological concepts. (shrink)

Para analizar el debate entre dos pensadores considerados marxistas, este texto propone situarlos dentro de una tradición filosófica representada por José Ortega y Gasset. Esta tradición recogía de manera original debates filosóficos internacionales y sólo desde la misma puede comprenderse la propuesta de acabar con las Facultades de Filosofía defendida en 1968 por Manuel Sacristán y contestada por Gustavo Bueno. La reconstrucción de dicho debate rescata una reflexión sobre la filosofía, de procedencia orteguiana, que permite respuestas originales al (...) problema de la autonomía de la filosofía y al de la relación con otros saberes. Esa reflexión fue actualizada críticamente en el debate entre ambos autores, aunque hasta ahora ha pasado relativamente desapercibida. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Was Isaac Newton an Arian?Thomas C. PfizenmaierHistorians of Newton's thought have been wide ranging in their assessment of his conception of the trinity. David Brewster, in his The Life of Sir Isaac Newton (1831), was fully convinced that Newton was an orthodox trinitarian, although he recognized that "a traditionary belief has long prevailed that Newton was an Arian."1 Two reasons were used to defend his conclusion that (...) Newton was orthodox. The first was a letter from John Craig, a friend of Newton, written shortly after Newton's death to John Conduitt, the husband of Newton's niece. In this letter Craig remarked that Newton's theological opinions "were sometimes different from those which are commonly received" but that he hoped Conduitt would publish Newton's theological papers, "that the world may see that Sir Isaac Newton was as good a Christian as he was a mathematician and philosopher."2 The second reason with which Brewster defended his conclusion was his acknowledgment that the doctrine of the trinity itself had variations.I had no hesitation when writing the Life of Sir Isaac Newton in 1830, in coming to the conclusion that he was a believer in the Trinity; and in giving this opinion on the creed of so great a man, and so indefatigable a student of scripture, I was well aware that there are various forms of Trinitarian truth, and various modes of expressing it, which have been received as orthodox in the purest societies of the Christian Church.3L. T. More in his biography Isaac Newton gently chided Brewster for not publishing some of the crucial manuscripts, which eventually became [End Page 57] part of the Keynes collection.4 From these additional manuscripts More reached the conclusion that Newton was not orthodox but an Arian. He proceeded to say that Newton was not only an Arian but, because of the manner in which he understood Jesus' role as prophet, a Unitarian.5More recently the famous British economist John M. Keynes, who considered it a great "impiety" that the Portsmouth family's collection of Newton's non-scientific manuscripts were dispersed at the Sotheby's auction in 1936 and who recovered about half of them creating the "Keynes" collection at Cambridge, provided yet a third interpretation of Newton's thought.Very early in life Newton abandoned orthodox belief in the Trinity. At this time the Socinians were an important Arian sect amongst intellectual circles. It may be that Newton fell under Socinian influences, but I think not. He was rather a Judaic monotheist of the school of Maimonides. He arrived at this conclusion, not on so-to-speak rational or skeptical grounds, but entirely on the interpretation of ancient authority. He was persuaded that the revealed documents give no support to the Trinitarian doctrines which were due to late falsifications. The revealed God was one God.6Among contemporary scholars, the consensus is that Newton was an Arian rather than a Socinian.7 This view is clearly expressed by Richard [End Page 58] Westfall who writes, "Well before 1675, Newton had become an Arian in the original sense of the term. He recognized Christ as a divine mediator between God and man, who was subordinate to the Father who created him."8 Yet Frank Manuel, in his The Religion of Isaac Newton (1974), advises that we not try to push Newton into a theological categorization too quickly. He reminds us that Newton was, if nothing else, an original thinker.It is an error to seize upon his antitrinitrianism in order to pigeonhole him in one of the recognized categories of heresy—Arian, Socinian, Unitarian, or Deist.9So how did Isaac Newton conceive of the trinity? In exploring his writing on the subject we will be guided by two principles mentioned above. The first is Brewster's insight that the trinitarian doctrine has in fact been understood with a certain degree of variety within the sphere of orthodoxy. The second is from Manuel's reminder, that we must resist the temptation to make Newton "fit" some predetermined category or school of trinitarian thought. We will begin by looking at the resources available for studying... (shrink)

The identification of a “new” handwriting of Manuel Chrysoloras allows to assign to him a number of hitherto unpublished witnesses, all preceding his teaching activity in Florence from 1397. This new dossier illustrates Chrysoloras’ youth in Constantinople, providing precious and so far unknown information on his family, his father John, his studies in the anti-Palamite milieux with Isaac Argyros and Demetrios Kydones, and, of course, his books, his graphic education, and his readings. Among these, a special place is (...) occupied by Aristotle’s logic: particular attention is therefore paid to a mock-up of a manuscript containing Aristotle’s Organon with a marginal commentary, here attributed to Chrysoloras and realized in a well-known manuscript by his master Argyros. (shrink)

Theory change is a central concern in contemporary epistemology and philosophy of science. In this paper, we investigate the relationships between two ongoing research programs providing formal treatments of theory change: the (post-Popperian) approach to verisimilitude and the AGM theory of belief change. We show that appropriately construed accounts emerging from those two lines of epistemological research do yield convergences relative to a specified kind of theories, here labeled “conjunctive”. In this domain, a set of plausible conditions are identified which (...) demonstrably capture the verisimilitudinarian effectiveness of AGM belief change, i.e., its effectiveness in tracking truth approximation. We conclude by indicating some further developments and open issues arising from our results. (shrink)