The crucial phase of speciation is argued to be the evolution of mating cross-incompatibility (prezygotic incompatibility) between the genotypes distinguishing the prospective species populations. Based on this idea, a single-locus model of speciation is presented, which is shown to be biologically plausible and may help to settle the controversy as to the biological significance of single-locus modes of speciation. The model involves three alleles, two of which characterize in homozygous state the prospective species populations and in heterozygous state their hybrids. (...) The third allele represents a mutant which is equivalent to one of the first two alleles with the exception that it inhibits mating with carriers of the third allele. This third allele is fixed in one population and immigrates into a second population which contains the mutant inhibiting matings with members of the former population. Migration in the reverse direction does not occur. Proceeding from a widely applicable concept of fitness and mating preference it is shown that postzygotic incompatibility (hybrid or heterozygote disadvantage) alone suffices to trigger evolutionary replacement of the extant mating relations in the population receiving immigrants by any arbitrary degree of prezygotic incompatibility. This corroborates Wallace's hypothesis and emphasizes the potential biological relevance of speciation by reinforcement (parapatric speciation) at single gene loci. (shrink)

When applied to a family of sets, the term differentiation designates a measure of the totality of those members which appear in only one of the sets. This basic set theoretic concept involves the formation of intersections, unions, and complements of sets. However, populations as special kinds of sets may share types, but they do not share the carriers of these types; intersections of different populations are thus always empty. The resulting conceptual dilemma is resolved by considering the joint representation (...) of members of different populations that have the same type; populations then intersect with respect to joint representation of types. Two forms of representation reflect relative and absolute characteristics of differentiation by accounting for the distributions of types as relative frequencies within populations (as is commonly done) and as absolute frequencies (including effects of population sizes on differentiation), respectively. Corresponding classes of differentiation measures are developed, and existing measures are discussed in relation to these classes. In particular, the affinity of the measurement of distances between populations and the special case of differentiation of two-population families is examined in order to distinguish between the notions of distance and differentiation. (shrink)

A measure of association is introduced that is based on a conceptual rather than a model approach in order to ensure its broad applicability. The basis of the concept involves two variables or traits and of members of a population. The association of the -state with the -state is measured by the degree to which members of given -state share their -state. This formulation yields an index of association, which is applicable to all categories of traits, including discontinuous and continuous (...) traits as well as combinations of these. Complete association of one trait with the other is equivalent to the existence of a functional relationship of the second to the first trait. Therefore, the degree of association can be understood as the closeness of the relations between two variables to a non-specified functional relationship. This feature in connection with the asymmetry of the index attests its suitability for cause-effect analyses. In fact, the conceptual approach to the measurement of association yields a conclusive method of detection and description of functional relationships between variables together with a method for quantification of the strictness of these relationships. The legitimacy of the correlation coefficient and of disequilibrium indices as measures of association is briefly addressed. (shrink)

Because of their elementary significance in almost all fields of science, measures of association between two variables or traits are abundant and multiform. One aspect of association that is of considerable interest, especially in population genetics and ecology, seems to be widely ignored. This aspect concerns association between complex traits that show variable and arbitrarily defined state differences. Among such traits are genetic characters controlled by many and potentially polyploid loci, species characteristics, and environmental variables, all of which may be (...) mutually and asymmetrically associated. A concept of directed association of one trait with another is developed here that relies solely on difference measures between the states of a trait. Associations are considered at three levels: between individual states of two variables, between an individual state of one variable and the totality of the other variable, and between two variables. Relations to known concepts of association are identified. In particular, measures at the latter two levels turn out to be interpretable as measures of differentiation. Examples are given for areas of application (search for functional relationships, distribution of variation over populations, genomic associations, spatiogenetic structure). (shrink)

The isolation principle rests on defining internal and external differentiation for each subset of at least two objects. Subsets with larger external than internal differentiation form isolated groups in the sense that they are internally cohesive and externally isolated. Objects that do not belong to any isolated group are termed solitary. The collection of all isolated groups and solitary objects forms a hierarchical (encaptic) structure. This ubiquitous characteristic of biological organization provides the motivation to identify universally applicable practical methods for (...) the detection of such structure, to distinguish primary types of structure, to quantify their distinctiveness, and to simplify interpretation of structural aspects. A method implementing the isolation principle (by generating all isolated groups and solitary objects) is proven to be specified by single-linkage clustering. Basically, the absence of structure can be stated if no isolated groups exist, the condition for which is provided. Structures that allow for classifications in the sense of complete partitioning into disjoint isolated groups are characterized, and measures of distinctiveness of classification are developed. Among other primary types of structure, chaining (complete nesting) and ties (isolated groups without internal structure) are considered in more detail. Some biological examples for the interpretation of structure resulting from application of the isolation principle are outlined. (shrink)

On philosophical thoughts of Nikolaus Driyarkara, an Indonesian Jesuit educator and philosopher; collection of articles.

While evenness is understood to be maximal if all types (species, genotypes, alleles, etc.) are represented equally (via abundance, biomass, area, etc.), its opposite, maximal unevenness, either remains conceptually in the dark or is conceived as the type distribution that minimizes the applied evenness index. The latter approach, however, frequently leads to conceptual inconsistency due to the fact that the minimizing distribution is not specifiable or is monomorphic. The state of monomorphism, however, is indeterminate in terms of its evenness/unevenness characteristics. (...) Indeed, the semantic indeterminacy also shows up in the observation that monomorphism represents a state of pronounced discontinuity for the established evenness indices. This serious conceptual inconsistency is latent in the widely held idea that evenness is an independent component of diversity. As a consequence, the established evenness indices largely appear as indicators of relative polymorphism rather than as indicators of evenness. In order to arrive at consistent measures of evenness/unevenness, it seems indispensable to determine which states are of maximal unevenness and then to assess the position of a given type distribution between states of maximal evenness and maximal unevenness. Since semantically, unevenness implies inequality among type representations, its maximum is reached if all type representations are equally different. For given number of types, this situation is realized if type representations, when ranked in descending order, show equal differences between adjacent types. We term such distributions “stepladders” as opposed to “plateaus” for uniform distributions. Two approaches to new evenness measures are proposed that reflect different perspectives on the positioning of type distributions between the closest stepladders and the closest plateaus. Their two extremes indicate states of complete evenness and complete unevenness, and the midpoint is postulated to represent the turning point between prevailing evenness and prevailing unevenness. The measures are graphically illustrated by evenness surfaces plotted above frequency simplices for three types, and by transects through evenness surfaces for more types. The approach can be generalized to include variable differences between types (as required in analyses of functional evenness) by simply replacing types with pairs of different types. Pairs, as the new types, can be represented by their abundances, for example, and these can be modified in various ways by the differences between the two types that form the pair. Pair representations thus consist of both the difference between the paired types and their frequency. Omission of pair frequencies leads to conceptual ambiguity. Given this specification of pair representations, their evenness/unevenness can be evaluated using the same indices developed for simple types. Pair evenness then turns out to quantify dispersion evenness. (shrink)

Although Gregory wrote very little about this. he acknowledged that natural reason can lead us from the orderliness of the physical world to the existence of God; in this, he followed the tradition of Athanasius and other Greek fathers. Unlike Aquinas, he did not seek to present the argument a; deductive: in fact his argument is inductive, and of die same kind as - we now realize - scientists and historians use when they argue from phenomena to then explanatory cause. (...) Gregory wrote hardly anything about how one could obtain knowledge of the truths of the Christian revelation by arguments from non-question-beggining premises; but in his conversations with the Turks he showed that he believed that there are good arguments of this kind. Almost all of Gregory's writing about knowledge of God concerned how one could obtain this by direct access in prayer: this access, he held is open especially to monks, but to a considerable degree also to all Christians who follow the divine commandments. (shrink)

This book attempts to resolve some of the oldest and most bitter controversies between the Eastern and Western Christian churches: those concerning the doctrine of God, the nature of salvation, and theological method, all of which converge in the doctrine of deification. Deification was the dominant patristic model of salvation and remained the essential paradigm in the East but was thought to have disappeared from Western theology by the Middle Ages. A. N. Williams examines two key thinkers, each of whom (...) is championed as the authentic spokesman of his own tradition and reviled by the other side. Taking Thomas Aquinas as representative of the West and Gregory Palamas for the East, she presents fresh readings of their work that both reinterpret each thinker and show an area of commonality between them much greater than has previously been acknowledged. (shrink)

The fourteenth-century Greek hesychast and controversialist, Gregory Palamas, has been so successfully cast as "the other" in Western theological discourse that it can be difficult to gain a sympathetic hearing for him. In the first part of this book, Norman Russell traces the historical reception of Palamite thought in Orthodoxy and in the West, and investigates how "Palamism" was constructed in the early twentieth century by both Western and Eastern theologians (principally Martin Jugie and John Meyendorff) for polemical or (...) apologetic purposes. Russell argues that we need to go behind these ideological constructions in order to gain a true perception of the teaching of Gregory Palamas. In his recent survey of Palamite scholarship, Robert Sinkewicz noted that it is now time to raise the larger questions. The second part of the book attempts to do this, following the contours of Palamas' thinking in three areas: his relationship to tradition, his philosophy, and his theology. Russell shows that Palamite thought, when freed of misunderstanding and misrepresentation, has the potential to enrich our understanding of divine-human communion. This study contributes to the changing paradigm of scholarship on Palamas, nudging it towards the point at which Palamite thought can be used fruitfully by contemporary Western and Eastern theologians without the need to subscribe to what has been regarded as "Palamism". (shrink)

The 13th and 14th centuries represented the most productive and influential period in the history of philosophy and theology in the West. A parallel and less influential (for the West) proliferation of arguments and theories took place in the East, at the same time, as a result of the defence of the Hesychastic movement offered by St Gregory Palamas and his followers. The papers brought together in this volume discuss the importance of Palamite ideas for the understanding of God (...) in terms of divine energies, and for contemporary approaches to solving perennial problems in science, metaphysics, aesthetics, and ethics. Some of the contributors take a more reserved evaluation of the Palamite corpus, preferring to highlight similarities and differences between Palamas and the chief representatives of Medieval Scholasticism, such as Thomas Aquinas, Duns Scotus and Ockham. Other essays offer a radical re-evaluation of the Western history of philosophy and theology, preferring to bring out the reasons for Western philosophical and theological shortcomings and providing a wider critique on Western culture. Contributors to this volume include some of the top scholars on Palamite studies from the fields of philosophy, theology, aesthetics, cultural criticism, and art theory. As such, it represents a particularly useful resource for advanced undergraduate students, postgraduate students and researchers in Christian theology and philosophy, Byzantine cultural studies and aesthetics. (shrink)

In what follows, I examine the views of Metropolitan Amfilohije’s views on St Gregory Palamas and Orthodoxy, primarily focusing on his PhD thesis, which was defended at the University of Athens, Faculty of Theology in 1973, and published in Thessaloniki in the same year. I claim that his views there not only show him defending Palamas, but also highlight the need for a strengthening of Palamism in Greece and abroad. Some of the problems, which he identified in 1973, (...) exist in Orthodoxy today and his suggestion that all contemporary Orthodox intellectuals should persist in the Philosophy and Theology of Palamism seems to be the only way to solve these problems, even today. (shrink)

Gregory Palamas (1296–1357) was a prominent Byzantine monk and theologian. He is best known for his writings in defence of the hesychasts, monks of Mount Athos.

The scholarly contributions gathered together in this volume discuss themes related to the cultural, social and ethical dimension of St Gregory Palamas’ works. They relate his mystical philosophy and theology to contemporary debates in metaphysics, philosophy of language, ethics, philosophy of culture, political philosophy, epistemology, and philosophy of religion and theology, among others. The book considers a variety of topics of special interest to Christian theologians, philosophers and art historians including church and state relations, similarities and differences between (...) class='Hi'>Palamas, contemporary phenomenologists and philosophers of language, and hesychast influences on late Byzantine iconography. (shrink)

In this paper we try to give some further evidence concerning the chronology of Palamas’ treatise Contra Beccum. Taking into consideration different parameters, external and internal, we incline to think that this treatise was composed – or, at least, reworked – in 1355, approximately at the same period when Palamas published the second edition of his Logoi apodeiktikoi.

© The Author 2016. Published by Oxford University Press on behalf of The Scots Philosophical Association and the University of St Andrews. All rights reserved. For permissions, please e-mail: [email protected] God is a collection of papers reflecting a 2012 conference on the theology and philosophy of St Gregory Palamas. The collection is avowedly Orthodox in orientation and as such assumes the acceptance of certain normative theological principles relating both to fundamental theological positions and to the interpretation of Palamas. (...) These show themselves both positively and negatively: positively with regard to the pious intention of the editor and many of the contributors, and negatively with regard to the critical position taken towards Western theology and culture. For the present reader, this is not in itself a problem and has the positive virtue of candour, but it can detract from the persuasiveness of a work that... (shrink)

The theological formulation of the “eternal manifestation of the Spirit through the Son”, developed by the patriarch of Constantinople Gregory of Cyprus in the 13th century, has been the subject of numerous studies in the 20th century and played an important role in the renewal of Trinitarian Orthodox theology. The interpretations are however diverging. Most theologians see in this formulation the manifestation of the uncreated energy, which would have been formalized later by Gregory Palamas. Others understand it as a (...) hypostatic reality concerning the third Person of the Trinity. This paper contributes to the discussion by re-analyzing the main texts of Gregory of Cyprus and of Gregory Palamas on this matter. In a first step, we defend the thesis that in the thought of the Byzantine patriarch, this expression truly concerns the hypostasis of the Spirit. In a second step, we question the existence of the theme of an “eternal manifestation” of the uncreated energy in the work of Gregory Palamas. (shrink)

Die Bestimmung des byzantinischen Gottesdenkens als «System» ist immer ein scandalum gewesen. Es wird als solches eher von seinen Kritikern begriffen, während seine Fürsprecher diese Bezeichnung überwiegend ablehnen. Wenn die byzantinischen Autoren in das Zentrum der Gotteserkenntnis eine Erfahrung oder eine Praxis stellen, die als Quelle der Theologie und als «wahre Philosophie» betrachtet werden, so ist zu erwarten, daß sie, Erfahrung oder Praxis, in systematischen Schriften selten und unwillig besprochen werden. Vielmehr begründen die meisten Autoren das Erscheinen ihrer Texte mit (...) dem Widerstand gegen gewisse Irrlehren. Diese Motivation bestimmt den hauptsächlich polemischen Charakter der Schriften und erklärt auch den Mangel eines explizierten philosophischen oder theologischen Systems im scholastischen Sinn. Das besagt aber nicht, daß die byzantinische Denkweise kein immanentes System und keine eigene Strukturen besitzt. Die Grundelemente dieser Systematik sind der Gegenstand der vorliegenden Überlegung. (shrink)

In this paper, we examine the concepts ‘destination’, ‘revelation’, ‘foreknowledge’, ‘will’, ‘transmission’, ‘motion’, and ‘grace’, as they appear in Gregory Palamas’ treatise De opera-tionibus divinis. According to the Christian theologian, these terms correspond to specific ways of God’s manifestation, i.e. His natural and supernatural revelation. Since they illuminate God’s energies, but not His essence, they are participated by the beings of the natural world. The first two terms mainly refer to a general version of the revelation, while the third (...) contains epistemological elements as well and the fourth contains elements referring also to the divine will. The fifth term condenses the content of the afore-mentioned terms seen as an ad extra bestowment. By means of these concepts, Palamas preserves the ontological difference between the supernatural and the natural, while, at the same time, he defines the exact way of their communion, which excludes pantheism. He introduces into the divine realm the state of distinction, which, however, does not restrict its unity at all. He accepts the development of a metaphysical multitude, which is regulated by the divine uniqueness. What emerges is not a kind of Neoplatonic polytheism, but the infinite richness of the divine existence. Thus, Palamas steadily moves within the tradition founded by Ps.-Dionysius the Areopagite, Maximus the Confessor, John Damascene, and George Pachymeres, the main characteristic of which is ontological monism. This is a tradition which formulated common places as to the content, the concepts and the relevant methodology, while the distinction between negative and affirmative theology is dominant. (shrink)

In this study, focusing our attention on Gregory Palamas’ treatise under the title Περί θείας ενώσεως και διακρίσεως, we attempt to investigate, first of all, the volitional nature and the polymorphism of the divine energies and their relation to the divine essence. We also attempt to approach the divine distinction as a good “procession” and to prove, relying exclusively on the Christian thinker’s text, the inconsistencies according to his view that arise from the positions supported by Barlaam and Akindynos (...) regarding the fact that the (divine) distinction is a creature. Regarding the matter on distinction, we conclude that it is a concept with a clearly different meaning when it comes to divine matters from the meaning that it gets when it concerns the created reality. From the gnoseological point of view, we focus our attention on the fact that the created beings are a source of knowledge for the revealed divine power-energy. (shrink)