The Simplest Quantified Modal Logic (SQML) is controversial because it seems to conflict with some of our most basic intuitions about what is possible and what is necessary. Two controversial principles, the Barcan Schema (BS) and Necessary Existence NE, are valid in SQML models. Informally expressed, BS requires that, if it is possible that something is F, then there is something that is possibly F. This result seems to conflict with the intuition that there is some property F such that F could have been exemplified, though is not possibly exemplified by any existing thing. NE conflicts with the intuition that there could have been more/different existents than there actually are and the intuition that those things that actually exist could have failed to exist. The primary goal of this thesis is to provide a semantics for SQML that justifies the validity of BS and NE with these intuitions in mind. This is the focus of the fifth section of the thesis. In the first four sections of the thesis, I discuss prior attempts to meet my primary goal, all of which I consider unsuccessful. According to my view, which I call M-combinatorialism, the world is comprised of simples, mereological sums of those simples and universals that the former objects exemplify. I argue that we can justify the validity of BS by appealing to these facts about simples and sums: (1) simples are arranged such that the sums of these simples exemplify certain properties, (2) the actual arrangement of any given number of simples is a contingent matter and (3) had the simples that are actually arranged to form the complex objects in the actual world been arranged differently, the sums of these simples could have exemplified radically different properties. Insofar as Combinatorialists construct all possible individuals only out of actual individuals, they are committed to the necessary existence of those actual individuals, which allows the M-Combinatorialist to justify the validity of NE. So, the M-Combinatorialist is able to provide an adequate semantics for SQML. In the final section, I defend my view against objections.

My guiding question is this: how does what is metaphysically differ from what was, will be, or might have been? The first half of the dissertation concerns ontology: are the apparent disputes over the existence of merely past, merely future, and merely possible entities genuine and nontrivial disputes? After demarcating the various positions one might take in these disputes, I argue that the disputes are, in fact, genuine. I then offer—in the second half of the dissertation—a limited defense of presentism, the view that only present things exist. In particular, I defend presentism against one of the most significant classes of objections to it—the class of objections claiming that it cannot account for a variety of past-oriented truths. In giving this defense, I draw on insights from the dispute between modal actualists—those who hold that everything is actual— and their rivals. / text

En raison de sa présence récurrente dans les ensembles paléontologiques d’Europe au Pléistocène, l’hyène des cavernes (Crocuta crocuta spelaea GOLDFUSS) est un carnivore particulièrement étudié en taphonomie. Depuis le XIXème siècle, la reconnaissance du rôle joué par les grands prédateurs, et plus particulièrement de l’hyène, dans la formation des assemblages osseux, a permis de dégager les grandes tendances écologiques et évolutives de ces carnivores (habitat en grotte, consommation osseuse, chasse vs. charognage, compétition interspécifique, interaction Homme-Carnivores). L’éthologie de l’hyène tachetée fossile (accumulateur d’ossements, ostéophagie) repose largement sur le développement des travaux écologiques et néo-taphonomiques depuis les années 1970. Le présent travail porte sur un bilan paléontologique et taphonomique des hyénidés modernes et Pléistocènes. Une première partie est consacrée à la présentation synthétique des 3 principaux genres (Crocuta, Hyaena, Parahyaena) et concerne leur systématique, biogéographie et ostéométrie. Ce dernier point permet de confirmer d’une part les fluctuations de masse corporelle des hyènes en relation avec les changements climatiques au cours du Pléistocène et d’autre part la difficulté à évaluer le dimorphisme sexuel à partir des éléments squelettiques crâniens et postcrâniens. Une seconde partie porte sur l’étude de 14 échantillons osseux modernes et fossiles produits par les hyénidés. Six accumulations en contexte de repaires et 3 ensembles de plein-air composent les séries modernes. Elles représentent des contextes écologiques et géographiques distincts (Djibouti et Afrique du Sud) et sont rapportées aux trois espèces d’hyènes (repaires : Crocuta : Dumali (NR Ongulés = 421), Heraide (NR Ongulés = 216), Yangula Ari (NR Ongulés = 133), Oboley (NR Ongulés = 259) ; Hyaena : Datagabou (NR Ongulés = 352) ; Parahyaena : Uniab (NR Ongulés = 568) ; kill-sites de Crocuta : Ali Daba : NR Ongulés = 40 ; Dumali : NR Ongulés = 185 ; Heraide : NR Ongulés = 460). L’analyse taphonomique de ces assemblages permet de caractériser les modifications produites par les hyénidés modernes. Ce modèle est ensuite pris en compte dans l’étude de 5 repaires d’hyène tachetée fossile inédits : Artenac c10 (OIS5c ; NRDT = 1301), Peyre (OIS5e ; NRDT = 2815), Grand Abri aux Puces Réseau Supérieur (100ka ; NRDT = 2360), Fouvent (OIS3 ; NRDT = 3347) et Conives (OIS3 ; NRDT = 1717). Afin de caractériser objectivement la signature taphonomique des hyènes fossiles, deux autres séries, plus anciennes (Pléistocène moyen), ont été brièvement prises en considération (Ceyssaguet (Pachycrocuta brevirostris) et Lunel-Viel 1 (Crocuta spelaea intermedia)) ainsi que deux échantillons osseux produits par d’autres grands Carnivores (le jaguar européen (Panthera onca gombaszoegensis) d’Artenac I et II et le loup (Canis lupus) moderne de Pologne). Les analyses comparées d’ensembles osseux créés par les Hyénidés, Félidés et grands Canidés permettent de reconsidérer les critères de caractérisation couramment utilisés en Taphonomie archéologique. Il apparait que les Carnivores partagent des caractéristiques taphonomiques communes (morphométrie des traces de dents, morphotypes de consommation, distribution squelettique des proies), peu favorables à l’identification spécifique ou/et générique des Carnivores ayant consommés des restes osseux. Le comportement ostéophagique de l’hyène (fossile) se distingue de celui des autres grands prédateurs par : une importante production des éclats diaphysaires d’os longs, la présence récurrente de coprolithes et enfin un nombre élevé d’os et/ou d’éclats ingérés. Parmi ces derniers, le spectre anatomique des éléments régurgités d’une part ainsi que leur degré de dissolution important d’autre part caractérisent significativement les séries paléontologiques produites volontairement par les hyènes. Ces critères pourraient constituer les éléments de diagnose taphonomique les plus intéressants. / (Crocuta crocuta spelaea GOLDFUSS) is a carnivore particularly studied in taphonomy. For the XIXth century, the recognition of the role played by large predators, and more particularly the (cave) hyena, in bone assemblage formation, allowed to precise main ecological and evolutionary trends of these carnivores (cave occupation, consumption of bones, predation vs scavenging, interspecific competition, Humans-Carnivores interaction). The behavior of the fossil spotted hyena (accumulator of bones, osteophagy) is mainly based on the development of the ecological and neotaphonomic works since the 1970s. The present work concerns a paleontological and taphonomic survey of Modern and Pleistocene Hyenids. A first part is dedicated to the synthetic presentation of the 3 main genera (Crocuta, Hyaena, Parahyaena) concerning their systematics, biogeography and osteometrics. This last point, particularly developed, allows to confirm on one hand the fluctuations in body mass of hyenas in connection with climate change and on the other hand the difficulty estimating the sexual dimorphism from cranial and postcranial elements. A second part concerns the study of 14 modern and fossil bone samples produced by Hyenids. Modern samples (6 dens and 3 kill-sites) come from different ecological and geographical contexts (Republic of Djibuti, South Africa). Dens are as follows : Crocuta : Dumali (Ungulate NISP = 421), Heraide (Ungulate NISP = 216), Yangula Ari (Ungulate NISP = 133), Oboley (Ungulate NISP = 259) ; Hyaena : Datagabou (Ungulate NISP = 352) ; Parahyaena : Uniab (Ungulate NISP = 568). Kill-sites are as follows : Crocuta : Ali Daba : Ungulate NISP = 40 ; Dumali : Ungulate NISP = 185 ; Heraide : Ungulate NISP = 460). The taphonomic analysis of these bone samples allows to characterize modifications produced by modern Hyenids. This model is then taken into account in the study of 5 unpublished fossil spotted hyena dens of : Artenac c10 (MIS 5c ; Ungulate NISP = 1301), Peyre (MIS 5e ; Ungulate NISP = 2815), Grotte aux Puces, réseau supérieur (100ka ; Ungulate NISP = 2360), Fouvent (MIS 3 ; Ungulate NISP = 3347) and Conives (MIS 3 ; 1717). To characterize objectively the taphonomic signature of fossil hyenas, two other older series (Middle Pleistocene), were briefly considered (Ceyssaguet (Pachycrocuta brevirostris) and Lunel-Viel 1 (Crocuta spelaea intermedia)) as well as two bone samples produced by other large Carnivores (the European jaguar (Panthera onca gombaszoegensis) of Artenac I and II and the modern wolf (Canis lupus) of Poland). Comparisons of those bone assemblages created by Hyenids (modern Crocuta: 139 dens, modern Hyaena: 63 dens; modern Parahyaena: 68 dens ; Crocuta crocuta spelaea: 30 sites), Felidae and large Canids allow to reconsider the criteria of characterization usually used in archaeological Taphonomy. It seems that Carnivores share common taphonomic characteristics (toothmark morphometry, morphotypes of consumption, sketelal parts of preys), and ttherefore those criteria donot appear favorable to a specific or/and generic identification of Carnivores having consumed bones. The (fossil) hyena osteophagic behavior distinguishes itself from that of the other large predators by: an important production of shaft fragments, the recurring presence of coprolithes and finally a high number of ingested bones. Among the latter, the anatomical spectrum of regurgitated elements on one hand as well as their degree of dissolution mattering on the other hand characterizes significantly the paleontological series produced voluntarily by hyenas These criteria could constitute the elements of diagnosis taphonomique the most interesting.

The aim of this paper is to provide a formulation of the modal cosmological argument for the existence of a necessary entity, that is more resistant to criticism than those hitherto formulated. The conclusion is that there exists a necessary entity powerful enough to causally sustain the world. It has only two substantial premises, which are very innocuous. The argument requires no assumption that contingent entities must have a cause, or even that they normally have a cause, or the impossibility of infinite regresses, or any particular theory of time, and works irrespectively of which modal framework is accepted.

Le problème de l'existence est réputé l´un de plus anciennes et de plus difficiles à résoudre de la philosophie: Que voulons-nous exprimer quand nous disons que quelque chose existe ou, pire encore, que quelque chose n´existe pas? Intuitivement, il semble que nous avons tous une prise ferme sur ce que nous voulons exprimer. Mais comment devrions-nous expliquer la différence – s´il y en a – entre les énoncés existentiels d´une coté et les plus communs énoncés prédicatifs de l´autre? Quelle est la différence entre dire que quelque chose existe et dire, par exemple, que quelque chose est rouge, lourde, moue, etc.? Dans cette étude nous allons nous pencher sur ces questions.Dans la première partie, cette étude porte sur les auteurs qui ont étés les plus persuasifs et les plus influents à creuser l´écart qui sépare les énoncés existentiels de plus communs énoncés prédicatifs. Notamment, il s´agirait ici de David Hume, Immanuel Kant, Franz Brentano et Gottlob Frege. Selon cette famille d'approches l'existence devient quelque chose de très différent d'une propriété des objets. Dans la deuxième partie, cette étude se penche sur des tentatives plus récentes qui ont pris la direction opposé et sont allez jusqu´à réduire l'existence à une propriété (plus ou moins) ordinaire des objets. Les philosophes qui seront discutés ici seront Alexius Meinong, Richard Routley, Terence Parsons, William Rapaport, Edward Zalta et Graham Priest.Finalement, la troisième partie de cette étude développe une approche selon laquelle la notion d'existence est étroitement liée à la notion de vérité: dire que telle ou telle chose existe est équivalent à dire qu'il est vrai que quelque chose est telle et telle. L'avantage de cette stratégie est, d´une coté, qu'elle ne réduit pas l´énoncé que quelque chose n´existe pas á une contradiction - un résultat fréquent ceci des approches discutées dans la première partie. De l´autre coté, cette stratégie évite les épicycles communs aux approches discutées dans la deuxième partie, lesquelles sont strictement liés à la réduction de l'existence à une propriété des objets. / The problem of existence is reputed to be one of the oldest and most intractable of philosophy: What do we mean when we say that something exists or, even more challengingly, that something does not exist? Intuitively, it seems that we all have a firm grip upon what we are saying. But how should we explain the difference – if there is any – between statements about existence and other, garden-variety predicative statements? What is the difference between saying that something exists and saying, for instance, that something is red, heavy, soft, etc.? These questions provide the focus for the present study.In the first part, this study addresses those authors that have been most effective and influential at widening the gap between statements about existence and garden-variety predicative statements. These are David Hume, Immanuel Kant, Franz Brentano, and Gottlob Frege. According to this family of approaches, existence becomes something very different from a property of objects. In the second part, this study turns to more recent attempts that have moved in the opposite direction by trying to reduce existence to a – more or less – plain property of objects. The philosophers that are going to be discussed here are Alexius Meinong, Richard Routley, Terence Parsons, William Rapaport, Edward Zalta, and Graham Priest. Eventually, the third part of this study develops an account according to which the notion of existence is strictly linked to the notion of truth: To say that such and such a thing exists is to say that it is true that something is such and such. The advantage of this strategy is that it does not make it contradictory to say that something does not exist – a frequent upshot of the approaches discussed in the first part. At the same time, this strategy avoids the epicycles common to the approaches discussed in the second part, which are strictly linked to the reduction of existence to a property of objects.