Imagination has recently attracted considerable attention from epistemologists and is recognized as a source of belief and even knowledge. One remarkable feature of imagination is that it is often and typically agentive: agents decide to imagine. In cases in which imagination results in a belief, the agentiveness of imagination may be taken to give rise to indirect doxastic control and epistemic responsibility. This observation calls for a proper understanding of agentive imagination. In particular, it calls for the development of a (...) semantics of imagination ascriptions. In the present paper an earlier suggestion by Ilkka Niiniluoto for a logic of imagination is considered. This proposal does not capture the agentive nature of imagination, and an alternative semantics is suggested. The new semantics combines the modal logic of agency with the neighbourhood semantics from alethic modal logic. (shrink)

This paper deals with various substructural propositional logics, in particular with substructural subsystems of Nelson's constructive propositional logics N– and N. Doen's groupoid semantics is extended to these constructive systems and is provided with an informational interpretation in terms of information pieces and operations on information pieces.

The paper provides a uniform Gentzen-style proof-theoretic framework for various subsystems of classical predicate logic. In particular, predicate logics obtained by adopting van Behthem''s modal perspective on first-order logic are considered. The Gentzen systems for these logics augment Belnap''s display logic by introduction rules for the existential and the universal quantifier. These rules for x and x are analogous to the display introduction rules for the modal operators and and do not themselves allow the Barcan formula or its converse to (...) be derived. En route from the minimal modal predicate logic to full first-order logic, axiomatic extensions are captured by purely structural sequent rules. (shrink)

Although it is not younger than other areas of non-classical logic, paraconsistent logic has received full recognition only in recent years, largely due to the work of, among others, Newton da Costa, Graham Priest, Diderik Batens, and Jerzy Perzanowski. A logical system Λ is paraconsistent if there is a set of Λ-formulas Δ ∪ {A} such that in Λ one may derive from Δ both A and its negation, and the deductive closure of Δ with respect to Λ is different (...) from the set of all formulas. If from Δ one may derive a formula and its negation, Δ is said to be syntactically inconsistent. But is every syntactically inconsistent set of formulas contradictory? In classical logic and many non-classical logics, every syntactically inconsistent set is unsatisfiable, that is, semantically inconsistent. If contradictoriness means semantical inconsistency, there is, up to logical equivalence, only one contradiction. In paraconsistent logics, there are usually many non-equivalent formulas representing the semantically unique contradiction in a non-paraconsistent logic. So when is a formula the contradiction of another formula, and, moreover, how does the notion of contradiction relate to the notions of contrariety and negation? (shrink)

book I. The nature of the state.-- book II. The social foundations of the state.-- book III. The constitution of the state.-- book IV. The administration of the state.-- book V. The state in international intercourse.

Band 1. Stellenindex und Konkordanz zu Johann Nicolaus Tetens' Über die allgemeine speculativische Philosophie.

A dynamic description model of the flight path a dragonfly takes is required in order to derive the encounter frequency of the dragonfly males visiting a pond. It is considered as the first part of a realistic description of the regulation of dragonfly density at the pond by behavioural interaction. Since the dragonfly males fly strictly along the shoreline of the pond, their displacement may be perceived as a quasi linear movement. The flight paths of dragonflies were recorded in field (...) by registering at regular time intervals the number of the shoreline section. in which the dragonfly was staying at that moment. The recorded flight paths show a wide variety from circling around the pond or flying widely to and fro to remaining in a narrow sector of the shoreline . The records were classified into 9 flight style groups. The flight style is temperature dependent, but there are also individual differences between the dragonflies. The strategy adopted for model building is to start with the most simple assumptions and parameters. The dynamic performance of each model is assessed by simulations. The model has to be extended until the simulated flight path patterns resemble the observed patterns. In a model with one parameter the displacement for every time interval is given by a stochastic decision using the probabilities evaluated from the observed frequencies of step length . This model was run with different sets of data. The simulated patterns using the data from all records together slightly resemble some observed patterns. They represent, however, only a small range of the variability observed. With data from the different style groups or the single records the simulated patterns are much more variable, but they are too irregular and contain too many turns . Therefore the description model was extended by a second parameter determining the direction of each step. The probability of turning is dependent on the number of steps already taken in the same direction . The probabilities are evaluated from the observed frequencies of step series. With the data from all records together, this model yields patterns more similar to the observed flight paths but they still represent only a restricted range of the observed variability. The patterns obtained using the data from the different style groups or from the single records cover the full range of the observed variability and they resemble closely the observed patterns even in minute details . Thus this description model together with the data from the flight style groups is accepted as fully sufficient for the present purpose. The simulations allow the assessment of the range of chance variability . The assumptions implied in the description model were corroborated by statistical tests. The approach developed here for the quantification of the behaviour of dragonflies is generally applicable to stochastic behaviour. Um die Häufigkeit der Kämpfe zwischen Libellenmannchen am Gewässer vom Verhalten der einzelnen Individuen ableiten zu können, wurde ein dynamisches Modell des Flugverhaltens einzelner Libellen aus Freilandbeobachtungen abgeleitet. Das Modell soll ein erster Schritt zu einer realistischen Beschreibung sein, wie bei Libellen die Individuendichte durch Verhaltensinteraktionen geregelt wird. Da die Libellenmannchen streng an der Uferlinie entlang fliegen, kann ihre Flugbahn als quasi eindimensionale Bewegung aufgefaßt werden. Die Flugbahnen einzelner Männchen registrierte ich, indem ich in regelmäßigen Zeitintervallen die Nummer des'Uferabschnitts , in dem sich die Libelle gerade aufhielt, auf Tonband sprach. Die registierten Flugbahnen sind sehr verschiedenartig. Zwischen Bahnen, bei denen die Libellen immer in einer Richtung um das Gewässer kreisten, bis zu solchen, bei denen sie in einem engen Uferbereich hin and her flogen, gibt es alle Übergänge . Die Flugbahnen warden in 9 Gruppen verschiedener Flugstile eingeteilt. Der Flugstil ist temperaturabhängig and individuell verschieden. Die Strategie der Modellentwicklung war, mit einem Modell mit möglichst einfachen Voraussetzungen and Parametern zu beginnen, seine dynamische Leistung mit Simulationen zu prüfen, und die Modellbeschreibung so lange zu erweitern, bis die simulierten Flugbahnmuster den tatsächlich beobachteten Mustern gleichen. Im ersten Modell wurde die Ortsveränderung in jedem Zeitintervall mit einer stochastischen Entscheidung bestimmt, bei der Wahrscheinlichkeiten verwendet warden, die sich aus den beobachteten Haufigkeiten der Schrittweiten ergaben . Simulationen dieses Modells mit den aus allen Flugbahnregistrierungen gemeinsam ausgewerteten Daten ergaben Flugbahnmuster, die zwar manchen beobachteten ähnelten, aber nur einen kleinen Bereich der beobachteten Vielfalt darstellten. Mit den Daten aus den einzelnen Flugstilgruppen ergab sich insgesamt eine grofie Variabilitat, die simulierten Flugbahnen waren aber zu unregelmäßig and enthielten zu viele Richtungswechsel . Deshalb wurde das Modell durch einen Parameter erweitert, der für jedes Zeitintervall die Flugrichtung bestimmt. Die Wahrscheinfchkeit umzukehren hängt davon ab, wieviele Zeitintervalle bereits die gleiche Richtung beibehalten wurde . Die Wahrscheinlichkeitswerte dafür warden aus den beobachteten Haufigkeiten der Schrittserien in eine Richtung bestimmt. Dieses Modell ergibt in Simulationen mit den aus allen Registrierungen gemeinsam ausgewerteten Daten Flugbahnen, die den Originalen ähnlich sind, aber nur einen beschränkten Bereich der vielfalt darstellen. Simulationen mit den Daten aus den einzelnen Flugstilgruppen dagegen ergeben die vollebeobachtete Variabilitat and die erhaltenen Flugbahnmuster gleichen den beobachteten Originalen auch in kleinen Einzelheiten . Dieses Modell kann deshalb zusammen mit den Daten der einzelnen Flugstilgruppen als befriedigende Beschreibung des Flugverhaltens angesehen werden. Die Simulationen erlauben, den Bereich der zufälligen Variabilitat abzuschätzen . Die im Modell gemachten Annahmen warden durch statistische Tests bestätigt. Der hier zur Beschreibung des Verhaltens von Libellen entwickelte Ansatz ist allgemein anwendbar auf stochastisches Verhalten. (shrink)