2 research outputs found
RAMIFIED TYPE THEORY AS INTENSIONAL LOGIC
Ovaj doktorski rad sastoji se od dva glavna dijela. Prvi se dio bavi pitanjem Å”to sustava Äine funkcije u razgranatoj teoriji tipova Bertranda Russella, kako ju je izložio u ļ¬lozoļ¬jskome uvodu prvoga izdanja Principia Mathematica.U tome se dijelu rada brani eliminativistiÄko tumaÄenje i pokuÅ”ava pokazati da Russell sam stavaÄne funkcije u Principia razumije samo kao izraze, kao tzv. nepotpune simbole, koji ne oznaÄavaju nikakve izvanjeziÄne predmete poput pojmova ili atributa.This doctoral thesis consists of two main sections. The ļ¬rst section addresses the background ontology of Bertrand Russellās ramiļ¬ed type theory as described in Principia Mathematica. More precisely, it deals with the question of the ontological status of propositional functions. The concept of a propositional function is one of the central concepts of Russellās theory of types, both in the ļ¬rst draft of the theory in āAppendix Bā of The Principles of Mathematics andinitsmatureformulationintheļ¬rsteditionofPrincipia.However,howtounderstandwhat Russell meant by āpropositional functionsā remains controversial. What are propositional functions? Are they some sort of intensional abstract entities, like properties and relations, or just expressionsofthelanguageoftypetheory,i.e.openformulas?Aneliminativistinterpretationis proposedandclaimedthatRussellāspropositionalfunctionsaretobeunderstoodonlyasexpressions,astheso-calledāincompletesymbolsā,whichdonotdenoteanyextra-linguisticobjects, such as attributes, whether in realist or constructivist sense. It is argued that the ramiļ¬ed type theory of Principia should not be understood as an abandonment of Russellās earlier substitutional theory, but rather as its continuation. The ramiļ¬ed type hierarchy is a consequence of Russellās belief that the paradoxes of propositions that plagued the substitutional theory can only be avoided by some kind of a type differentiation of propositions. On the other hand, the elimination of propositional functions (as well as propositions) from the ontology of Principia is a consequence of Russellās conception of logic as universal science, which must contain only one type of genuine variables ā viz., completely unrestricted entity variables, with everything that exists as their values. The doctrine of the unrestricted variable has been formulated by Russell in The Principles of Mathematics and is an inseparable part of his understanding of logic. The theory of denoting phrases he developed in āOn Denotingā provided the tool for the elimination of higher-order entities from the background ontology of his logic. This way, Russell managed to retain a complex type hierarchy of expressions needed to avoid the paradoxes and at the same time preserve the doctrine of the unrestricted variable. At the end of the ļ¬rst section, certain advantages of rejecting the doctrine of the unrestricted variable and Russellās understanding of propositional functions as incomplete symbols are recognized, and suggested that the interpretation of the ramiļ¬ed hierarchy as an ontological hierarchy of concepts might be philosophically justiļ¬ed. Inthesecondsection,aformalsystemofcumulativeintensionalramiļ¬edtypetheory(KIRTT) is presented, guided by a realist interpretation of a ramiļ¬ed type hierarchy and with semantics based on an intensional generalization of Henkin models. The aim was to formalize certain metaphysical intuitions concerning the nature of intensional entities and to sketch one possible formal theory of concept
RAMIFIED TYPE THEORY AS INTENSIONAL LOGIC
Ovaj doktorski rad sastoji se od dva glavna dijela. Prvi se dio bavi pitanjem Å”to sustava Äine funkcije u razgranatoj teoriji tipova Bertranda Russella, kako ju je izložio u ļ¬lozoļ¬jskome uvodu prvoga izdanja Principia Mathematica.U tome se dijelu rada brani eliminativistiÄko tumaÄenje i pokuÅ”ava pokazati da Russell sam stavaÄne funkcije u Principia razumije samo kao izraze, kao tzv. nepotpune simbole, koji ne oznaÄavaju nikakve izvanjeziÄne predmete poput pojmova ili atributa.This doctoral thesis consists of two main sections. The ļ¬rst section addresses the background ontology of Bertrand Russellās ramiļ¬ed type theory as described in Principia Mathematica. More precisely, it deals with the question of the ontological status of propositional functions. The concept of a propositional function is one of the central concepts of Russellās theory of types, both in the ļ¬rst draft of the theory in āAppendix Bā of The Principles of Mathematics andinitsmatureformulationintheļ¬rsteditionofPrincipia.However,howtounderstandwhat Russell meant by āpropositional functionsā remains controversial. What are propositional functions? Are they some sort of intensional abstract entities, like properties and relations, or just expressionsofthelanguageoftypetheory,i.e.openformulas?Aneliminativistinterpretationis proposedandclaimedthatRussellāspropositionalfunctionsaretobeunderstoodonlyasexpressions,astheso-calledāincompletesymbolsā,whichdonotdenoteanyextra-linguisticobjects, such as attributes, whether in realist or constructivist sense. It is argued that the ramiļ¬ed type theory of Principia should not be understood as an abandonment of Russellās earlier substitutional theory, but rather as its continuation. The ramiļ¬ed type hierarchy is a consequence of Russellās belief that the paradoxes of propositions that plagued the substitutional theory can only be avoided by some kind of a type differentiation of propositions. On the other hand, the elimination of propositional functions (as well as propositions) from the ontology of Principia is a consequence of Russellās conception of logic as universal science, which must contain only one type of genuine variables ā viz., completely unrestricted entity variables, with everything that exists as their values. The doctrine of the unrestricted variable has been formulated by Russell in The Principles of Mathematics and is an inseparable part of his understanding of logic. The theory of denoting phrases he developed in āOn Denotingā provided the tool for the elimination of higher-order entities from the background ontology of his logic. This way, Russell managed to retain a complex type hierarchy of expressions needed to avoid the paradoxes and at the same time preserve the doctrine of the unrestricted variable. At the end of the ļ¬rst section, certain advantages of rejecting the doctrine of the unrestricted variable and Russellās understanding of propositional functions as incomplete symbols are recognized, and suggested that the interpretation of the ramiļ¬ed hierarchy as an ontological hierarchy of concepts might be philosophically justiļ¬ed. Inthesecondsection,aformalsystemofcumulativeintensionalramiļ¬edtypetheory(KIRTT) is presented, guided by a realist interpretation of a ramiļ¬ed type hierarchy and with semantics based on an intensional generalization of Henkin models. The aim was to formalize certain metaphysical intuitions concerning the nature of intensional entities and to sketch one possible formal theory of concept