Jessica Leech

This book sets out a Kant-inspired theory of modality, driven by a methodology which takes seriously questions about the function of modal judgment as a guide to a metaphysics of modality. It argues that we need logical modal concepts as a condition on our ability to think, and metaphysical modal concepts as a condition on our ability to think objectively. Concordant with this, it argues that logical necessity has its source in the laws of thought and that metaphysical necessity is relative to conditions on objective thought. This this account of metaphysical necessity, which is termed “Modal Transcendentalism”, is then further developed, covering questions concerning necessary and contingent existence, de re necessity, essentialism, and modal epistemology.

Recently, a debate has developed between those who claim that essence can be explained in terms of de re modality (modalists), and those who claim that de re modality can be explained in terms of essence (essentialists). The aim of this paper is to suggest that we should reassess. It is assumed that either necessity is to be accounted for in terms of essence, or that essence is to be accounted for in terms of necessity. I will argue that we should assume neither. I discuss what role these key notions – essence and necessity – can reasonably be thought to contribute to our understanding of the world, and argue that, given these roles, there is no good reason to think that we should give an account of one in terms of the other. I conclude: if we can adequately explain de re modality and essence at all, we should aim to do so separately.

According to an increasingly popular view, the source of logical necessity is to be found in the essences of logical entities. One might be tempted to extend the view further in using it to tackle fundamental questions surrounding logical consequence. This chapter enquires: how does a view according to which the facts about logical consequence are determined by the essences of logical entities look in detail? Are there any more or less obvious problems arising for such a view? The chapter uncovers a prima facie result in favour of logical pluralism. However, it then goes on to raise some concerns for this result. It argues that, considered generally, it is difficult to see how essence could do all of the requisite work alone. The chapter also shows how considering things from the perspective of disputes between particular rival logics makes an interesting and important difference to the picture of things presented by the essentialist account.