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In this essay, McGinn argues for a version of ‘modal realism’ that denies the reality of possible worlds. Central to this discussion is a distinction between objectual and non‐objectual interpretations of modal expressions. Objectual interpretations affirm the reality of possible worlds, the existence of which McGinn flatly denies; whereas on the non‐objectual alternative, the semantic role of modal expressions is non‐referential. According to McGinn, the modal truth is to be grounded not in a realist ontology of possible worlds but in the manner in which real objects have the properties they do. In this way, McGinn remains a modal realist by locating modality in the modes of objects.

There is a set of principles, the Principles of Possibility, that constrains whether a description picks out a genuinely possible world. To grasp the concept of metaphysical necessity is to have tacit knowledge of this set of Principles and to apply them in evaluating modal statements and thoughts. For a statement to be necessary is for it to hold in all descriptions that are not excluded as possible by the principles of possibility. This integrates the metaphysics and epistemology of necessity, without collapsing into mind‐dependence and without a commitment to modal realism. The treatment of the metaphysics validates the modal systems T and S4.

This chapter explores the dialectic of the interaction between modal semantics and modal metaphysics. It begins by looking at three examples of places where semantic and substantive issues interact, and where it is contentious whether a problem calls for a semantic or a metaphysical solution. The first example is an argument from a semantic premise to a metaphysical conclusion that is fallacious; the second is a case of a semantic decision with a metaphysical motivation. The third example is a puzzle where it is controversial whether the puzzle should have a semantic or a metaphysical solution. In this case, it is argued that the metaphysical response is unnecessary—the puzzle is best dissolved on semantic grounds. After discussing these three examples, the chapter considers a specific semantic question about how the quantifiers should work in our modal quantification theory and the way that this question interacts with metaphysical questions about the nature of the modal reality that the language aims to describe. This will lead us to a consideration of more general questions about ontological commitment.

This chapter introduces basic concepts related to modality that occur throughout the book. It discusses kinds of necessity and possibility — particularly narrow and broad logical modalities. It introduces the concept of a possible world, and the different types of theory of possible worlds, as well as (briefly) the standard formal modal semantics. It also introduces some systems of modal logic and the notion of a counterfactual conditional.

In this chapter, the potentiality account of modality is spelled out. Metaphysical possibility is defined: it is metaphysically possible that p if and only if something has an iterated potentiality for p. The definition is shown to do justice to typical examples of metaphysical possibilities and necessities, and to provide the right logic for modality. The second half of the chapter is then concerned with developing a potentiality-based semantics for modal expressions in ordinary language, starting with the modal ‘can’ as a paradigmatic case. It is argued that the semantics, together with the metaphysics of potentiality, can account naturally for the context-sensitivity of modal language, and that it is in line with a range of important linguistic findings.

This chapter develops a non-orthodox conception of dispositions as individuated by their manifestation alone, not their manifestation plus a stimulus condition; and as closely related to possibility, not the counterfactual conditional. In the first part of the chapter this is done with the resources of standard, possible-worlds-based modal semantics. The second part then applies the insights from modal semantics to a nonreductive, realist account of dispositions. It is argued that to provide a realist metaphysical background to the context-sensitive ordinary disposition ascriptions, we need to accept a much more general notion of ‘potentiality’ which outruns the more ordinary notion of a disposition, covering the whole spectrum from what an object can barely do (a steel bridge’s potentiality to break) all the way to what it has to do (an electron’s potentiality to attract positively charged particles).

This chapter articulates three models of the undetermined future. Assuming that there are multiple future histories consistent with the past and the laws, we can maintain that (I) there is a unique actual future history, and it is determinate which history that is; (II) there is a unique actual future history, but it is indeterminate which history that is; (III) there is no such thing as the “unique actual future history”. Models (I) and (II) are united in terms of there being a unique actual course of history; models (II) and (III) are united in terms of there being no privileged history in the model. The author defends model (III). He further argues that will is a universal quantifier over all the causally possible histories consistent with the future directed facts. The author shows how this view combined with model (III) generates the view that future contingents are all false.