Choosing Your Nonmonotonic Logic: A Shopper’s Guide

The paper presents an exhaustive menu of nonmonotonic logics. The options are individuated in terms of the principles they reject. I locate, e.g., cumulative logics and relevance logics on this menu. I highlight some frequently neglected options, and I argue that these neglected options are particularly attractive for inferentialists

Expressing Validity: Towards a Self-Sufficient Inferentialism

For semantic inferentialists, the basic semantic concept is validity. An inferentialist theory of meaning should offer an account of the meaning of "valid." If one tries to add a validity predicate to one's object language, however, one runs into problems like the v-Curry paradox. In previous work, I presented a validity predicate for a non-transitive logic that can adequately capture its own meta-inferences. Unfortunately, in that system, one cannot show of any inference that it is invalid. Here I extend the system so that it can capture invalidities

A Nonmonotonic Sequent Calculus for Inferentialist Expressivists

I am presenting a sequent calculus that extends a nonmonotonic consequence relation over an atomic language to a logically complex language. The system is in line with two guiding philosophical ideas: (i) logical inferentialism and (ii) logical expressivism. The extension defined by the sequent rules is conservative. The conditional tracks the consequence relation and negation tracks incoherence. Besides the ordinary propositional connectives, the sequent calculus introduces a new kind of modal operator that marks implications that hold monotonically. Transitivity fails, but for good reasons. Intuitionism and classical logic can easily be recovered from the system

When Structural Principles Hold Merely Locally

In substructural logics, structural principles may hold in some fragments of a consequence relation without holding globally. I look at this phenomenon in my preferred substructural logic, in which Weakening and Cut fail but which is supra-intuitionistic. I introduce object language operators that keep track of the admissibility of Weakening and of intuitionistic implications. I end with some ideas about local transitivity

Do the Virtues Make You Happy?

We answer the title question with a qualified “No.” We arrive at this answer by spelling out what the proper place of the concept 'happiness' is in a neo-Aristotelian virtue ethics: (1) Happiness in the sense of personal well-being has only a loose relation to virtue; it doesn't deserve any prominent place in virtue ethics. (2) Happiness in the sense of flourishing is impossible without virtue, but that doesn't imply that individual actions should aim at flourishing. (3) Instead, flourishing sets the standard of good practical reasoning; it is hardly ever the proper aim of a practical inference. This paper begins with a common (mis)interpretation of neo-Aristotelian virtue ethics, on which it is a form of rational egoism. We then develop our alternative understanding against this foil

Minimally Nonstandard K3 and FDE

Graham Priest has formulated the minimally inconsistent logic of paradox (MiLP), which is paraconsistent like Priest’s logic of paradox (LP), while staying closer to classical logic. We present logics that stand to (the propositional fragments of) strong Kleene logic (K3) and the logic of first-degree entailment (FDE) as MiLP stands to LP. That is, our logics share the paracomplete and the paraconsistent-cum-paracomplete nature of K3 and FDE, respectively, while keeping these features to a minimum in order to stay closer to classical logic. We give semantic and sequent-calculus formulations of these logics, and we highlight some reasons why these logics may be interesting in their own right