The variety DMM of De Morgan monoids has just four minimal subvarieties. The join-irreducible covers of these atoms in the subvariety lattice of DMM are investigated. One of the two atoms consisting of idempotent algebras has no such cover; the other has just one. The remaining two atoms lack nontrivial idempotent members. They are generated, respectively, by 4-element De Morgan monoids C4 and D4, where C4 is the only nontrivial 0-generated algebra onto which finitely subdirectly irreducible De Morgan monoids may (...) be mapped by noninjective homomorphisms. The homomorphic preimages of C4 within DMM constitute a proper quasivariety, which is shown to have a largest subvariety U. The covers of the variety within U are revealed here. There are just ten of them. In exactly six of these ten varieties, all nontrivial members have C4 as a retract. In the varietal join of those six classes, every subquasivariety is a variety—in fact, every finite subdirectly irreducible algebra is projective. Beyond U, all covers of [or of ] within DMM are discriminator varieties. Of these, we identify infinitely many that are finitely generated, and some that are not. We also prove that there are just 68 minimal quasivarieties of De Morgan monoids. (shrink)

There is an extensive literature on time travel in both philosophy and physics. Part of the great interest of the topic stems from the fact that reasons have been given both for thinking that time travel is physically possible—and for thinking that it is logically impossible! This entry deals primarily with philosophical issues; issues related to the physics of time travel are covered in the separate entries on time travel and modern physics and time machines. We begin with the definitional (...) question: what is time travel? We then turn to the major objection to the possibility of backwards time travel: the Grandfather paradox. Next, issues concerning causation are discussed—and then, issues in the metaphysics of time and change. We end with a discussion of the question why, if backwards time travel will ever occur, we have not been visited by time travellers from the future. (shrink)

A number of authors have noted that vagueness engenders degrees of belief, but that these degrees of belief do not behave like subjective probabilities. So should we countenance two different kinds of degree of belief: the kind arising from vagueness, and the familiar kind arising from uncertainty, which obey the laws of probability? I argue that we cannot coherently countenance two different kinds of degree of belief. Instead, I present a framework in which there is a single notion of degree (...) of belief, which in certain circumstances behaves like a subjective probability assignment and in other circumstances does not. The core idea is that one’s degree of belief in a proposition P is one’s expectation of P’s degree of truth. (shrink)

In an earlier paper I argued that time travellers cannot change the past: alleged models of changing the past either fall into contradiction or else involve avoiding, not changing, the past. Goddu has responded to my argument, maintaining that his hypertime model involves time travellers changing (not avoiding) the past. In the present paper I first discuss what would be required to substantiate the claim that a given model involves changing rather than avoiding the past. I then consider Goddu's hypertime (...) model and an earlier model due to Meiland. I argue that neither author does what would be required to substantiate the claim that the model involves changing (not avoiding) the past. I go on to give reasons for the stronger claim that no-one can present a coherent model and also substantiate the claim that it involves changing (not avoiding) the past. (shrink)

In the context of classical (crisp, precise) sets, there is a familiar connection between the notions of counting, ordering and cardinality. When it comes to vague collections, the connection has not been kept in central focus: there have been numerous proposals regarding the cardinality of vague collections, but these proposals have tended to be discussed in isolation from issues of counting and ordering. My main concern in this paper is to draw focus back onto the connection between these notions. I (...) propose a natural generalisation to the vague case of the familiar process of counting precise collections. I then discuss the relationships between this process of counting and various notions of ordering and cardinality for vague sets. Some existing views concerning the cardinality of vague collections fit better than others with my proposal about how to count the members of such a collection. In particular, the idea that we should approach cardinality via certain formulas of a logical language -- which has been prominent in the recent literature -- is less attractive than other existing proposals. (shrink)

Le névrosé est un homme qui demeure infantile et s'enferme dans un refuge imaginaire. Sans courage, il est prisonnier des angoisses primitives. A partir d'une compréhension de la relation fondamentale entre l'angoisse et le courage s'éclaire la valeur proprement humaine de l'amour humain, de la rencontre, de la confrontation et de la liaison entre le Moi et le Toi comme une existence sous la forme du Nous - la „liebende Wirheit” dont parle Binswanger. Le mysterium tremendum de l'amour personnel pour (...) un ‘étranger’ - qui n'est donc n i la mère n i le père - est un risque existentiel par essence, c'est le franchissement du seuil vers une forme nouvelle de l'existence du Dasein. C'est la raison pour laquelle la route vers le Toi passe par l'angoisse et que l'engagement dans cette voie présuppose un Moi libre, courageux et responsable. C'est ce que nous apprend déjà le dicton : „Qui veut épouser la fille du roi doit d'abord supporter le tremblement de l'angoisse”. Le courage qui est ici nécessaire s'accomplit dans la liberté heureuse de ce qu'on a appelé le „discours-révélant” -par lequel le „langage-du-désir” de notre inconscience originelle est assumé et qu'il accomplit sa signification. (shrink)

A many-valued (aka multiple- or multi-valued) semantics, in the strict sense, is one which employs more than two truth values; in the loose sense it is one which countenances more than two truth statuses. So if, for example, we say that there are only two truth values—True and False—but allow that as well as possessing the value True and possessing the value False, propositions may also have a third truth status—possessing neither truth value—then we have a many-valued semantics in the (...) loose but not the strict sense. A many-valued logic is one which arises from a many-valued semantics and does not also arise from any two-valued semantics [Malinowski, 1993, 30]. By a ‘logic’ here we mean either a set of tautologies, or a consequence relation. We can best explain these ideas by considering the case of classical propositional logic. The language contains the usual basic symbols (propositional constants p, q, r, . . .; connectives ¬, ∧, ∨, →, ↔; and parentheses) and well-formed formulas are defined in the standard way. With the language thus specified—as a set of well-formed formulas—its semantics is then given in three parts. (i) A model of a logical language consists in a free assignment of semantic values to basic items of the non-logical vocabulary. Here the basic items of the non-logical vocabulary are the propositional constants. The appropriate kind of semantic value for a proposition is a truth value, and so a model of the language consists in a free assignment of truth values to basic propositions. Two truth values are countenanced: 1 (representing truth) and 0 (representing falsity). (ii) Rules are presented which determine a truth value for every proposition of the language, given a model. The most common way of presenting these rules is via truth tables (Figure 1). Another way of stating such rules—which will be useful below—is first to introduce functions on the truth values themselves: a unary function ¬ and four binary functions ∧, ∨, → and ↔ (Figure 2).. (shrink)

This work has been selected by scholars as being culturally important and is part of the knowledge base of civilization as we know it. This work is in the public domain in the United States of America, and possibly other nations. Within the United States, you may freely copy and distribute this work, as no entity (individual or corporate) has a copyright on the body of the work. Scholars believe, and we concur, that this work is important enough to be (...) preserved, reproduced, and made generally available to the public. To ensure a quality reading experience, this work has been proofread and republished using a format that seamlessly blends the original graphical elements with text in an easy-to-read typeface. We appreciate your support of the preservation process, and thank you for being an important part of keeping this knowledge alive and relevant. (shrink)

The idea that professional practices such as education should be based upon or at least be informed by evidence continues to capture the imagination of many politicians, policy makers, practitioners and researchers. There is growing evidence of the influence of this line of thought. At the same time there is a growing body of work that has raised fundamental questions about the feasibility of the idea of evidence-based or evidence-informed practice. In this paper I make a further contribution to this (...) discussion through an analysis of a number of assumptions that inform the discussion. I focus on the epistemological, ontological and praxeological dimensions of the discussion and in each domain identify a deficit. In the epistemological domain there is a knowledge deficit, in the ontological domain an effectiveness or efficacy deficit and in the practice domain an application deficit. Taken together these deficits not only raise some important questions about the very idea of evidence-based practice but also highlight the role of normativity, power and values. Against this background I outline the case for the idea of value-based education as an alternative for evidence-based education. As I am generally concerned about the expectations policy makers hold about what evidence can and should achieve in professional practices such as education, my contribution is primarily meant to provide educators and other professionals with arguments that can help them to resist unwarranted expectations about the role of evidence in their practices and even more so of unwarranted interventions in their practices. (shrink)

Het Leids-Haags Allegorieënlexicon toont nieuwe perspectieven op de maatschappelijke werkelijkheid met een actuele duiding van vijftig kernthema’s uit de wetenschap. De auteurs zijn de duale promovendi en hun promotores van Leiden University Dual PhD Centre The Hague. Ze worden daarbij geïnspireerd door de metafoor van de grot van Plato: Waar ben ik? Waar sta ik? Welk beeld zie ik? Hoe kan ik dat begrijpen? Er ontstaan beeldende voorstellingen van begrippen waarin op zoek wordt gegaan naar de centrale gedachten die ten (...) grondslag liggen aan die begrippen. Zo wordt de veranderende wereld waargenomen met het besef dat we nooit kunnen weten of we de gehele werkelijkheid kunnen zien of begrijpen. De waarneming is afhankelijk van de zichtpositie die de waarnemer inneemt. Zo ontstaan verbeeldingen van waarnemingen van ons menselijk bestaan. Zoals: assimilatie, creativiteit, gender, kunstenaarschap, magistraat, participatie, regels, tragedie en verzorgingsstaat. Eerst wordt actuele literatuur besproken. Daarna volgt discussie. Tenslotte neemt de auteur positie in. Met bijdragen van promotores Wilfried Admiraal, Ingrid van Biezen, Hans Borgman, Paul Cliteur, Jaap van den Herik, Rikki Holtmaat, Willem Otterspeer, Jos Raadschelders, Robert Tijssen, Wim Willems en promovendi. (shrink)

Dans cet article, dont le sujet peut paraître assez inattendu dans une revue de philosophie, l'auteur poursuit dans un cas déterminé les recherches qu'il a publiées dans son grand ouvrage sur la théorie générale des attitudes et des mouvements humains.Il y applique la même méthode assez complexe, mais qui tient surtout de la phénoménologie. Le football n'est de ce point de vue qu'un mode spécial de la relationde l'homme au monde. L'auteur rappelle d'abord la signification générale de cette relation. Il (...) s'applique ensuite à analyser la valeur propre de la balle, de la balleélastique surtout, comme objet de jeu. A la lumière de la distinction entre le mouvement du jet et celui du coup de pied il décrit la différence entre le jeu de paume et le football. Le coup de pied est plus agressif que le jet. Caractère d'agressivité qui s'accuse d'avantage encore lorsque dans le jeu, les coups de pied se répondent mutuellement.Aussi bien le football est-il une manifestation de masculinité sous la forme du jeu.On peut jeter comme une fille, mais le shot est essentiellement masculin, même lorsqu'on est femme. C'est pourquoi on n'a jamais réussi à introduire le football parmi les femmes. L'auteur analyse ensuite le caractère si particulièrement captivant du football.Il en trouve plusieurs raisons. Le joueur est entièrement absorbé par la situation, qu'il crée sans doute lui-même pour une part mais qui est constituée aussi par le jeu de l'adversaire et des autres hommes de son équipe. Il s'en suit que tout match est dans un certain sens une aventure. Par ailleurs quelque soit l'art du joueur, il ne peut jamais être parfait parce que le hasard intervient toujours à certains moments. De plus, le jeu se déroule d'une manière dramatique ; il traverse une série de phases critiques et aboutit finalement à une sorte de dénouement. Il faut reconnaître cependant que ces caractéristiques sont communes à plusieurs jeux sportifs sur le terrain, comme p. ex.le hockey et le rugby. L'élément spécifique du football reste, ce que le mot d'ailleurs exprime : le coup de pied au ballon. L'auteur s'interroge enfin au sujet de l'attraction que le football exerce sur le public, plus qu'aucun autre sport dans certains pays du moins. Il en voit la cause dans ce fait que le spectateur prend part d'une manière ambiguë à chaque phase du jeu. Celui qui ne joue pas au football est cependant en état de prendre part au jeu comme spectateur, et plus facilement qu'à beaucoup d'autres sports. Par ailleurs il s'y maintient dans une attitude critique. Le résultat incertain de chaque match entrepris dans de bonnes conditions, la perfection toujours relative du jeu, le rituel propre à ce sport, l'orgueil national ou local qui est engagé dans l'affaire, le culte des joueurs favoris et l'encouragement donné à tout cela par la presse, sont, par ailleurs les facteurs principaux de la popularité extraordinaire du football. Chaque époque et chaque peuple à son sport propre. Au monde actuel convient fort bien la popularité d'un jeu sportif à la fois local, national et international où se manifeste une agressivité masculine modérée ainsi qu'une aptitude technique qui peut s'exercer dans des entreprises dépourvues de danger et qui cependant présentent certains aspects d'un sensationnel tempéré et où peuvent se prendre un orgueil et une célébrité sans conséquences sérieuses. (shrink)

In spite of the seeming heterogeneity of topics in its title - Revolutions, Systems, and Theories - this volume purports to be something more than a random collection of Essays in Political Philosophy. The Colloquium of the Philosophy Department of the University of Western Ontario (29-31 Octo­ ber, 1971) at which initial versions of the first eight papers were delivered was entitled 'Political Theory'; and while the organizers anticipated and indeed welcomed topicality in the issues accorded priority arid in the (...) empirical evidence invoked, they were also hoping for a reasonably comprehensive explorat ion of some of the central issues of political philosophy. For this reason it was quickly decided that in such a field a philosophical focus on clarification of ordering concepts required the suppIement - and test - of researches into more particular subject maUers by social scientists. Thus, to speak in general terms (where the specializatlons and their taxonomies multi­ ply fissiparously!), contributors include political scientists, economists and sociologists (Barnard, Baston, Tullock, Rapoport) as well as philosophers (Scriven, Morgenbesser, Braybrooke, TayIor), and juxtaposed as proponents and commentators ·to generate exchanges across disciplinary frontiers. While the five additional invited papers are alI by professional philosophers, they extend the original Colloquium either by continuing controversy on its funda­ mental issues (e. g., Rubinoff, Nielsen, Roy) or by their continued explorations in what are acknowledged to be boundary areas (e. g., Schick, Wartofsky). The greatest topical emphasis is that on revolution. (shrink)

We analyse the relationship between applicability and effectiveness of legal norms from a philosophical perspective. In particular, we distinguish between two concepts of applicability. The external applicability of norms refers to institutional duties; a norm N is externally applicable if and only if a judge is legally obliged to apply N to some case c. Internal applicability refers instead to the sphere of validity of legal norms. A norm N is internally applicable to actions regulated by its sphere of validity. (...) We also explore the consequences of a thesis which maintains that applicability restricts the concept of effectiveness, so that only applicable norms can be considered effective. Our analysis illustrates that a proper reconstruction of the concept of applicability is of great importance not only for understanding the concept of effectiveness but also for providing insight into the nature of law. (shrink)

Patterns resulting from the sole interplay between reaction and diffusion are probably involved in certain stages of morphogenesis in biological systems, as initially proposed by Alan Turing. Self-organization phenomena of this type can only develop in nonlinear systems (i.e. involving positive and negative feedback loops) maintained far from equilibrium. We present Turing patterns experimentally observed in a chemical system. An oscillating chemical reaction, the CIMA reaction, is operated in an open spatial reactor designed in order to obtain a pure reaction-diffusion (...) system. The two types of Turing patterns observed, hexagonal arrays of spots and parallel stripes, are characterized by an intrinsic wavelength. We identify the origin of the necessary difference of diffusivity between activator and inhibitor. We also describe a pattern growth mechanism by spot splitting that recalls cell division. (shrink)