Modality and Logical Form

250 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1980.The logical form of an alethic modal judgement is given in part by a characterization of the semantic role of a modal qualification. Otherwise, a "formal" account of modality lacks the requisite degree of explanatory power. Explaining generally the semantic role of a modal qualification is significantly different from giving a truth theory for constructions of a standard logical grammar of truth functions and first-order quantification. For the purpose of explaining distinctive logical traits of our modal idiom, it is not enough to generalize familiar model-theoretic methods of defining a truth predicate for intensional languages. That semantic strategy abstracts from the operation of certain communicative constraints on the interaction of verbal forms and semantic values which is characteristic of modal talk. Our intuitive assessments of modal judgements do not make sense when that aspect is ignored.Our alternative account of the semantic role of a modal qualification shifts the explanatory burden from a truth predicate to a notion of speaker commitment. Our working hypothesis suggests what is qualified and how: an apodictic modal qualification is non-deviant only if the element modified serves, in the context, to express a claim whose assertion may or may not satisfy a demand for adequate warrant. More generally, a modal qualification is a propos when the inferential status of a certain claim is in question. An apodictic utterance is correctly made when an assertion of the associated claim in the context is sufficiently warrented, the kind of warrant and standards of adequacy being indicated by the utterance along with the context.According to the hypothesis a modal qualification is essentially context-relative to kinds of factors which pertain to a speaker's right to say something. This idea is used to explain the distinctive communicative utility of our modal idiom. Furthermore, it is the basis of an explanation of the referential opacity of alethic modality. Opacity is a manifestation of the operation of two kinds of discursive principles which figure prominently in the correctness of a modal judgement, according to our account of the semantic function of it. A modal qualification orients speaker and interlocutor to a relevant argumentative text. There are discursive principles which govern the formulation of such a text. Opacity results when imposing a correct interpretation on certain modal judgements requires that principles of the latter kind are violated.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD