One main goal of argumentation theory is to evaluate arguments and to determine whether they should be accepted or rejected. When there is no clear answer, a third option, being undecided, has to be taken into account. Indecision is often not considered explicitly, but rather taken to be a collection of all unclear or troubling cases. However, current philosophy makes a strong point for taking indecision itself to be a proper object of consideration. This paper aims at revealing parallels between (...) the findings concerning indecision in philosophy and the treatment of indecision in argumentation theory. By investigating what philosophical forms and norms of indecision are involved in argumentation theory, we can improve our understanding of the different uncertain evidential situations in argumentation theory. (shrink)

It's natural to think that the principles expressed by the statements "Promises ought to be kept" and "We ought to help those in need" are defeasible. But how are we to make sense of this defeasibility? On one proposal, moral principles have hedges or built-in unless clauses specifying the conditions under which the principle doesn't apply. On another, such principles are contributory and, thus, do not specify which actions ought to be carried out, but only what counts in favor or (...) against them. Drawing on a defeasible logic framework, this paper sets up three models: one model for each proposal, as well as a third model capturing a mixed view on principles that combines them. It then explores the structural connections between the three models and establishes some equivalence results, suggesting that the seemingly different views captured by the models are closer than standardly thought. (shrink)

An overview of hyperintensionality is provided. Hyperintensional languages have expressions with meanings that are more fine-grained than necessary equivalence. That is, the expressions may necessarily co-apply and yet be distinct in meaning. Adequately accounting for theories cast in hyperintensional languages is important in the philosophy of language; the philosophy of mind; metaphysics; and elsewhere. This entry presents a number of areas in which hyperintensionality is important; a range of approaches to theorising about hyperintensional matters; and a range of debates that (...) attention to hyperintensional constructions has generated. (shrink)

In normative reasoning one typically refers to intervals of time across which norms are intended to hold, as well as to alternative possibilities representing hypothetical developments of a given scenario. Thus, deontic modalities are naturally intertwined with temporal and metaphysical ones. Furthermore, contemporary debates in philosophy suggest that a proper understanding of fundamental ethical principles, such as the Ought-Implies-Can thesis, requires a simultaneous analysis of these three families of concepts. In the present article we propose a general formal framework which (...) allows for fine-grained multimodal reasoning in the normative domain. We provide an axiomatization for a novel system of propositional logic encoding the way in which possibilities and norms arising from different sources change over intervals of time. The usefulness of our framework is illustrated by analysing an ancient and particularly challenging `cold case', the Paradox of the Court. (shrink)

In this paper we argue that normative reasons are hyperintensional and put forward a formal account of this thesis. That reasons are hyperintensional means that a reason for a proposition does not imply that it is also a reason for a logically equivalent proposition. In the first part we consider three arguments for the hyperintensionality of reasons: an argument from the nature of reasons, an argument from substitutivity and an argument from explanatory power. In the second part we describe a (...) hyperintensional logic of reasons based on justification logics. Eventually we discuss the philosophical import of this proposal and highlight some limitations and possible developments. (shrink)

In What is Philosophy?, Deleuze and Guattari critique the relationship between formal logic and philosophy. They argue that since philosophy is the creation of concepts that are intensional, and formal logic reduces concepts to their extension, formal logic then has no special providence to decide philosophical questions. This may strike the logic-inclined philosopher as outdated given that there are now formal intensional logics designed to model meaning rather than reference. However, it will be shown that these logics too fail to (...) express the concept in a way that preserves its philosophical import. Doing so requires contrasting Deleuze and Guattari's account of the concept with Frege's to show how the latter persists even in intensional logics in the form of mathematical functions that are ultimately referential. This then results in support for Deleuze and Guattari's claim that formal logic is a useful tool, but that it is incapable of adjudicating philosophical disputes. (shrink)

Partial reasons are considerations in favor of something that, taken individually, are not sufficient to establish an obligation. I consider the extent to which partial reasons are reasons, and why they cannot be reduced to or identified with pro tanto reasons. I lay out two approaches to the content of reasons, the flat theory and the structured theory. I argue that parts of reasons are not partial reasons, by showing that natural ways to represent parts of reasons in the flat (...) theory and the structured theory lead to overgeneration problems with regard to partial reasons. I then formulate two notions of partial reasons: one based on a notion of partial support, which is in turn captured by the notions of full support and partial content, and one based on the notion of in exact verification. I show under which conditions the two notions of partial reasons (based on partial content, and based on inexact verification) coincide. (shrink)