This chapter gives an account of the origins of our present understanding of the natural/supernatural divide, showing how the terminology of the ‘supernatural’ first emerged in the Middle Ages and gradually assumed its modern form between the seventeenth and nineteenth centuries. The attendant ‘isms’—naturalism and supernaturalism—arrive at the end of this period, during the 1800s. The original context for the naturalism/supernaturalism distinction was neither science nor philosophy, but the sphere of biblical criticism. From there it was imported into a scientific context. The nineteenth century also witnessed attempts to reconstruct the history of science with a view to arguing for a long-standing alliance between naturalism and science. A more accurate portrayal of the relevant history shows, to the contrary, that ‘science’ had been consistently aligned with theistic assumptions about the regularities of nature. These regularities were formalised as laws of nature in the seventeenth century, at which time they were understood as divinely authored imperatives to which nature necessarily conformed. In the nineteenth century, what had originally been understood as expressions of the divine will were simply redescribed in purely naturalistic terms by advocates of naturalism. Ironically, they were now claimed to represent evidence against theistic readings of nature.

David Hume’s famous argument against believing miracle reports exemplifies several key issues relating to the emergence of modern naturalism. Hume uncritically assumes the universal and unproblematic nature of core conceptions such as ‘supernatural’ and ‘laws of nature’. Hume’s argument also presents him with a dilemma. He relies upon the weight of testimony to establish his case against believing miracle reports, but must also contend with the weight of testimony, across different times and cultures, to the existence of the supernatural. Hume resolves this by an appeal to historical progress accompanied by a dubious racial theory. These enable him to discount testimonies emanating from the past and from other cultures. ‘Hume’s dilemma’ has not gone away and, if anything, is even more acute since the traditions and beliefs of non-Western cultures are now more difficult to dismiss on the basis of dubious historical accounts of Western exceptionalism. This dilemma amounts to a tension between the ethics of belief and the demands of epistemic justice.

● Dynamical laws in evolutionary biology often take the form of a priori conditionals. The idea that a priori dynamical generalizations are laws is defended and shown to have anti-reductionist consequences. ● The definitions of determinism and indeterminism usually used in physics and philosophy differ from the definitions often used in population genetics. ● The question of what it means for a probability to have an objective interpretation is clarified. ● A necessary and sufficient condition is described for when indeterminism at the micro-level gives rise to determinism at the macro-level. It is argued that this condition is rarely if ever satisfied. ● Several objective interpretations of probability are canvased and criticized. ● The question is raised of why an interpretation of objective probabilities is needed. ● The concepts of inevitability, contingency, and sensitivity to initial conditions in evolutionary processes are explored. ● The question of whether evolution is an information-destroying process is investigated.

Chapter 7 examines Benjamin Worsley’s manifesto of natural sciences that contained utopian ideas about human capacity to overcome death, if only the right scientific approach and the right moral attitude could be achieved. Revelation substituted what Boyle believed was the impossibility of grasping moral natural law rationally. Therefore, the study of moral natural laws is practically irrelevant in his work. Boyle moved constantly between a self-sufficient and mechanistic idea of the physical world and recourse to an infinitely wise God as a guide to human knowledge. He wrote several ambitious works on these issues, which are nowadays considered foundational to the Scientific Revolution but remain practically unknown beyond specialist circles nowadays. The chapter looks in particular at The Origine of Formes and Qualities and A Free Enquiry into the Vulgarly Receiv’d Notion of Nature. These works articulate Boyle’s ambition to transmute everything in nature and his momentous critique of nature, a metaphysical and sacred concept that had been part of Western culture since at least the era of the great Greek philosophers.

Chapter 7, ‘One of Geometry’s Nicest Applications’, relates the digging of the Deep-George draining tunnel (1771–1800), named after George III, King of Great Britain and Hanover. During the planning phase, surveyors designed this engineering project with a previously unknown level of detail. Jean-André Deluc, Fellow of the Royal Society and reader to Queen Charlotte, visited the Harz mines three times as the operations were under way. Deluc’s geological and meteorological inquiries led him to perform barometric experiments in these mines. He relied on practitioners’ data to test and calibrate his instruments, marvelling about their precision in the Philosophical Transactions and the Journal des Sçavans. Scholars and amateurs – from Goethe to Watt – but also merchants and their wives rushed to visit the project. Year after year, journals reported to the public how the various sections of the tunnel connected seamlessly. In the late eighteenth century, the two worlds of natural scientists and mine engineers were meeting one last time, this time around common issues of precision, data gathering, and instrumentation.

What accounts for the fact that some physical events occur while others do not? This is a question of physical modality. Three models in contemporary analytic metaphysics have dominated the investigation of physical modality: the Neo-Humean Model, the Universals Model, and the Powers Model. Each model aims to explain, in ontologically conspicuous ways, the unfolding of possibilities in space and time. This chapter explains the Neo-Humean and Universals Models, then shows that while they explicitly deny a place for powers in their fundamental ontologies, they nonetheless implicate powers. That is, they subtly assume the reality of powers. As a result, the Powers Model is the way to go in explaining physical modality. However, there are different ways of conceiving powers. After describing variations of the Powers Model, the chapter returns to the main question posed in the introductory chapter: What is the nature of powers from the inside? Stricter attention to the internality of powers is necessary to better understand the Powers Model and its metaphysical commitments.

Through the 1600s, the fundamental laws of mechanics served as bridge principles to ontology and confirmation theory. By the mid-eighteenth century, the laws came to lose their former bridging function. As a result, the metaphysics and epistemology of classical mechanics became opaque. The chapter diagnoses several factors that catalyzed the changed status of basic laws.

In Chapter 2 I examine what appears to be a violation of the invariance of laws. Generalisations typically concern the behaviour of isolated systems, while explanations, confirmations, manipulations and predictions concern non-isolated systems. Ceteris paribus clauses, which are often attached to law statements, take account of the fact that systems are typically not on their own. Systems are interacted on and interfered with by other systems – they are not invariant with respect to the behaviour of other systems. Understanding how ceteris paribus clauses work helps us to understand why we can explain, confirm or manipulate the behaviour of systems that are parts of a larger whole. Analysis of the role of these clauses shows that we need to read laws (generalisations) as attributing multi-track dispositional properties to systems. The argument relies on an analysis of scientific practice only and is not committed to more far-reaching claims that are common in the metaphysics of science literature. There is no need to assume a sui generis conception of dispositional modality. I will argue that the modal aspects of dispositions can be explicated in terms of invariance relations.

In Chapter 1, I start by analysing the role of generalisations in scientific practice. Law statements or generalisations are involved in one way or another in explanation, confirmation, manipulation or prediction. I argue that these practices require a particular reading of the generalisations involved, namely, as making claims about the behaviour of systems. These practices therefore presuppose the existence of systems or things. Next, I look at the modal surface structure associated with laws. I use the term ‘surface structure’ to indicate that this structure may or may not be reduced to non-modal facts – as the Humean has it. I will sideline the debate about whether Humeanism is a tenable philosophical position. The positive claim I advance is that the modal surface structure can be explicated in terms of invariance relations – where I take invariance to be a modal notion.

This chapter places Kant’s conception of a priori laws within the framework of the legal metaphors. It introduces the relevant aspects of natural right theory and the notion of laws in the natural sciences as historical background to the legal metaphors. The main argument is that Kant’s notion of laws is embedded in his legal metaphors and his account of natural regularities as lawful also originates in the natural right framework. This serves as background to Kant’s account of the understanding as prescribing laws to nature and to thought. The background of Kant’s notion of laws in natural right and natural science shows how reason’s a priori laws are both descriptive of regularities in nature and prescriptive of valid judgements.