Duen-Min Deng

A proposition can be false but still true about a certain subject matter: e.g., the proposition that snow is white and expensive is false, yet still true about the color of snow. This paper investigates how this idea of ‘truth about a subject matter’ should be analyzed. I begin with the Simple Conjunction Theory, which explains the case by decomposing a false proposition into a true conjunct about the subject matter and a false conjunct irrelevant to it. While intuitive, this theory fails to account for non-conjunctive propositions. I then examine the Lewis-Yablo Theory, which invokes possible-world partitions to analyze subject matters. I show that this framework generalizes the Simple Conjunction Theory and accommodates non-conjunctive cases, but it also faces a counterexample. To resolve this, I propose modifications based on closeness relations among possible worlds. The resulting account preserves the explanatory motivations of the earlier theories while avoiding their difficulties.

False-premise-inference (FPI) cases—where a subject appears to acquire inferential knowledge by inferring from a false premise—challenge the standard view that inferential knowledge must be grounded in true premises. Existing responses, knowledge from falsehood and knowledge despite falsehood, prove unsatisfactory. We defend a third alternative: knowledge from partial truth. In FPI cases, the subject’s inferential knowledge is epistemized not by the false premise as a whole but by a true proper part of its content. Drawing on a fine-grained theory of propositional content, we show how to isolate this knowledge-generating component. Our approach resolves the puzzle by preserving the natural reading of the FPI cases while upholding the principle that knowledge-generating inferences are truth-conducive.

This volume brings together a group of logic-minded philosophers and philosophically oriented logicians to address a diversity of topics on the structural analysis of non-classical logics. It mainly focuses on the construction of different types of models for various non-classical logics of current interest, including modal logics, epistemic logics, dynamic logics, and observational predicate logic. The book presents a wide range of applications of two well-known approaches in current research: structural modeling of certain philosophical issues in the framework of non-classic logics, such as admissible models for modal logic, structural models for modal epistemology and for counterfactuals, and epistemological models for common knowledge and for public announcements; conceptual analysis of logical properties of, and formal semantics for, non-classical logics, such as sub-formula property, truthmaking, epistemic modality, behavioral strategies, speech acts and assertions. The structural analysis provided in this volume will appeal not only to graduate students and experts in non-classic logics, but also to readers from a wide range of disciplines, including computer science, cognitive science, linguistics, game theory and theory of action, to mention a few.

Consider the following argument, where ‘\’ abbreviates ‘the proposition that p’: It is possible that Socrates does not exist.Necessarily, if Socrates does not exist, then \ is true.Necessarily, if \ is true, then \ exists.Necessarily, if \ exists, then Socrates exists.Therefore, it is possible that Socrates exists and does not exist. How can one respond to this argument? Fine thinks that the argument involves an equivocation concerning the notion of truth for propositions: if we stand inside a possible world to evaluate the truth, in this ‘inner’ sense holds but fails; but if we stand outside, in this ‘outer’ sense holds but fails. In this paper we argue that such an equivocation response is obscure, ad hoc, and unmotivated.

We construct a causal-modeling semantics for both indicative and counterfactual conditionals. As regards counterfactuals, we adopt the orthodox view that a counterfactual conditional is true in a causal model M just in case its consequent is true in the submodel M∗, generated by intervening in M, in which its antecedent is true. We supplement the orthodox semantics by introducing a new manipulation called extrapolation. We argue that an indicative conditional is true in a causal model M just in case its con- sequent is true in certain submodels M∗, generated by extrapolating M, in which its antecedent is true. We show that the proposed semantics can account for some important minimal pairs nicely and naturally. We also prove a theorem showing under what conditions intervention and extrapolation will yield the same result, and thus explain how counterfactual and indicative conditionals would behave in a causal-modeling semantics.

Many metaphysical controversies can be understood as debates over whether some alleged entities are metaphysically possible. No doubt, with regard to these matters, we may have opinions or theories, commonsensical or sophisticated. But do we have knowledge of them? Can we really know that something is metaphysically possible, and if so, how? Several different answers have been offered in the literature, intending to illustrate how we may have knowledge of metaphysical modality. In this paper, I concentrate on a proposal by Timothy Williamson. On this account, our alleged knowledge of metaphysical modality is justified by and grounded in our capacity to handle ordinary mundane counterfactual conditionals. However, I argue that Williamson’s account fails, mainly because the modality involved in ordinary mundane counterfactuals is causal, and thus our capacity to handle them still falls short of giving us any knowledge of metaphysical modality. In the end of the paper, I also provide my own answer to the question. My answer is a sceptical one: we do not really have knowledge of metaphysical modality. But such ignorance is harmless, or so I argue.