Metaontological Studies relating to the Problem of Universals

My dissertation deals with metaontology or metametaphysics. This is the subdiscipline of philosophy that is concerned with the investigation of metaphysical concepts, statements, theories and problems on the metalevel. It analyses the meaning of metaphysical statements and theories and discusses how they are to be justified. The name "metaontology" is recently coined, but the task of metaontology is the same as Immanuel Kant already dealt with in his Critique of Pure Reason. As methods I use both historical research and logical (or rather semantical) analysis. In order to understand clearly what metaphysical terms or theories mean or should mean we must both look at how they have been characterized in the course of the history of philosophy and then analyse the meanings that have historically been given to them with the methods of modern formal semantics. Metaontological research would be worthless if it could not in the end be applied to solving some substantive ontological questions. In the end of my dissertation, therefore, I give arguments for a solution to the substantively ontological problem of universals, a form of realism about universals called promiscuous realism. To prepare the way for that argument, I argue that the metaontological considerations most relevant to the problem of universals are considerations concerning ontological commitment, as the American philosophers Quine and van Inwagen have argued, not those concerning truthmakers as such philosophers as the Australian realist D. M. Armstrong have argued or those concerning verification conditions as such philosophers as Michael Dummett have argued. To justify this conclusion, I go first through well-known objections to verificationism, and show that they apply also to current verificationist theories such as Dummett's theory and Field's deflationist theory of truth. In the process I also respond to opponents of metaphysics who try to show with the aid of verificationism or structuralism that metaphysical questions would be meaningless or illegitimate in some other way. Having justified the central role of ontological commitment, I try to develop a detailed theory of it. The core of my work is a rigorous formal development of a theory of ontological commitment. I construct it by combining Alonzo Church's theory of ontological commitment with Tarski's theory of truth.Väitöskirjani käsittelee metaontologiaa eli metametafysiikkaa. Tämä on se metafilosofian osa-alue, joka tutkii metafyysisten väitteiden ja termien merkitystä ja sitä, miten metafyysiset väitteet ja teoriat voitaisiin oikeuttaa. Metafysiikka tai ontologia on taas tiede, joka tutkii olevaa yleensä tai kaikkeutta kokonaisuutena. Menetelminä käytän sekä historiallista tutkimusta että loogista (tai pikemminkin semanttista) analyysiä. On olemassa kolme pääasiallista teoriaa siitä, mikä on metaontologian keskeisin käsite. Sellaiset filosofit kuin australialainen Armstrong ovat väittäneet, että se on totuustekijöiden (truthmakers) käsite. Sellaiset anti-realistiset filosofit kuin englantilainen filosofi Michael Dummett ovat taas väittäneet että se on todennettavuusehtojen (verification conditions) käsite. Argumentoin näitä kahta käsitystä vastaan ja kolmannen puolesta, jonka mukaan keskeisin käsite on ontologisten sitoumusten käsite, kuten amerikkalainen filosofi Quine on väittänyt. Argumentoin, että Quinen ontologisten sitoumusten teoria voidaan erottaa hänen muista ontologisista näkemyksistään, kuten hänen semanttisesta holismistaan, ontologisesta relativismistaan tai strukturalismistaan, mitkä ovat mielestäni virheellisiä. Väitöskirjani ydin on täsmällinen teoria ontologisista sitoumuksista, jonka rakennan yhdistämällä Alonzo Churchin teoriaa ontologisista sitoumuksista Alfred Tarskin totuusteoriaan. Metaontologinen tutkimus olisi arvotonta, ellei sitä voisi lopulta käyttää substantiivisten ontologisten kysymysten ratkaisemiseen. Käsittelen siksi väitöskirjani loppupuolella yhtä perinteistä ontologian ongelmaa, universaalien ongelmaa. Jo Aristoteles määritteli teoksessaan Tulkinnasta universaalien olevan olioita, jotka (Lauri Carlsonin käännöksen mukaan) luonnostaan predikoidaan (sanotaan) monesta. Universaaliongelma koskee sitä, ovatko tällaiset universaalit vain kielellisiä ilmauksia, kuten yleisnimet, verbit ja adjektiivit, tai ihmismielestä riippuvia olioita, kuten yleiskäsitteet, vai voidaanko myös sanoa, että maailmassa itsessään olevia olioita voidaan predikoida jostakin. Realistin mukaan vastaus on myöntävä. Esitän väitöskirjan lopussa alustavan argumentin universaaleja koskevan realismin puolesta

Power constructs and propositional systems

Bibliography : p. 161-176.Propositional systems are deductively closed sets of sentences phrased in the language of some propositional logic. The set of systems of a given logic is turned into an algebra by endowing it with a number of operations, and into a relational structure by endowing it with a number of relations. Certain operations and relations on systems arise from some corresponding base operation or relation, either on sentences in the logic or on propositional valuations. These operations and relations on systems are called power constructs. The aim of this thesis is to investigate the use of power constructs in propositional systems. Some operations and relations on systems that arise as power constructs include the Tarskian addition and product operations, the contraction and revision operations of theory change, certain multiple- conclusion consequence relations, and certain relations of verisimilitude and simulation. The logical framework for this investigation is provided by the definition and comparison of a number of multiple-conclusion logics, including a paraconsistent three-valued logic of partial knowledge

Constructions, inductive types and strong normalization

This thesis contains an investigation of Coquand's Calculus of Constructions, a basic impredicative Type Theory. We review syntactic properties of the calculus, in particular decidability of equality and type-checking, based on the equality-as-judgement presentation. We present a set-theoretic notion of model, CC-structures, and use this to give a new strong normalization proof based on a modification of the realizability interpretation. An extension of the core calculus by inductive types is investigated and we show, using the example of infinite trees, how the realizability semantics and the strong normalization argument can be extended to non-algebraic inductive types. We emphasize that our interpretation is sound for large eliminations, e.g. allows the definition of sets by recursion. Finally we apply the extended calculus to a non-trivial problem: the formalization of the strong normalization argument for Girard's System F. This formal proof has been developed and checked using the..

A pragmatic theory of truth and ontology

At the heart of my pragmatic theory of truth and ontology is a view of the relation between language and reality which I term internal justification: a way of explaining how sentences may have truth-values which we cannot discover without invoking the need for the mystery of a correspondence relation. The epistemology upon which the theory depend~ is fallibilist and holistic (chapter 2); places heavy reliance on modal idioms (chapter 4); and leads to the conclusion that current versions of realism and anti-realism are deficient (chapter 5). Just as my theory avoids the need for an epistemic 'given', it avoids the need for a metaphysical 'given' or 'joints'. I offer a view of the nature of philosophy and what it can properly achieve with respect to ontological questions (chapter 3); since those views lead me to believe that philosophical discussion about what exists should be restricted to 'entities' discussed in non-philosophical contexts, my views on how we should understand claims made about the existence of middle-sized physical objects (chapters 2 and 6), theoretical entities in science (chapter 6), and abstract entities in mathematics (chapter 7), give the thesis a schematic completeness. My theory leads me to a conception of inquiry which defends the cognitive status of moral statements whilst being critical of Kantian and utilitarian approaches to morality (chapter 8). Chapter 1 explores the views of my closest philosophical allies: William James and Nelson Goodman