DescriptionThe first two chapters of this dissertation defend the Deductive-Nomological Account of metaphysical explanation. Chapter 1 develops the Nomological Account of ground, – p1, …, pn ground q if and only if the laws of metaphysics determine q on the basis of p1, …, pn, – and the constructional theory of the metaphysical laws, – the laws are general principles that characterize construction-operations. Chapter 2 offers an analysis of the notion of determination involved in the Nomological Account: the laws determine q based on p1, …, pn if and only if q follows from p1, …, pn and the laws in the grounding-calculus. The grounding-calculus is characterized in terms of two inference rules and a suitable notion of ‘proof’. The rules are designed to analyze the input- and output notions that are intuitively associated with laws: the laws take some facts as input and deliver some other facts as output. Chapters 1 and 2 also go beyond the development of the positive view. Chapter 1 shows how the Nomological Account explains general patterns among grounding-truths, the modal force of ground, and certain connections between ground and construction. Chapter 2 shows why the Deductive-Nomological Account of metaphysical explanation escapes the objections to the traditional DN-account of scientific explanation, and it also outlines two views on logical explanation that are available to the proponent of the Nomological Account. Chapter 3 focuses on laws of nature and presents the Circularity Puzzle, which is a generalized version of a familiar circularity-based objection to Humeanism about the laws of nature. The three solutions to the Circularity Puzzle correspond to three different general views on the laws, one Anti-Humean and two Humean views. I argue that for the Anti-Humean, the Circularity Puzzle collapses into the familiar inference-problem, and for the Standard Humean, the solution to circularity-related worries lies in the rejection of the governing-conception of laws. I explain what I take to be the strongest response to the inference-problem.