Causal Models

This chapter shows how the ontology of power and influence can be used to interpret and extend the causal modelling framework developed by Judea Pearl, Peter Spirtes, Clark Glymour, and Richard Scheines. In particular, it is argued that the standard causal modelling framework suffers from an important limitation in that it is not truly modular. A modification to the standard framework is presented that overcomes this limitation. In the modified framework, the basic relations explicitly represent basic causal powers and the influences that they manifest. These ‘causal influence models’ can be used to generate standard causal models, and so can do everything that the standard causal models can do. It is argued, however, that there are both theoretical and practical reasons for preferring causal influence models over standard causal models.

Laws of Nature

This chapter investigates how an ontology of power and influence might help us answer the question ‘What is it to be a law of nature?’ In particular, the chapter investigates how this ontology might help us develop the dispositional essentialist account of laws as it is presented by Alexander Bird. It is argued that Bird's derivation of laws from dispositions only works if we combine the view that some properties are powers in Bird's sense (they have an essential dispositional nature that is modally fixed) with the view that the relevant properties are powers in the sense developed in this book (they are dispositions to manifest causal influence).

Emergence and the Failure of Reduction

This chapter explores the different ways in which the reductive method of explanation might fail, and asks what such failures might tell us about the world. In particular, the chapter investigates possible situations in which one or more of the assumptions identified in previous chapters fails. It is argued that the failure of one of these assumptions will give rise to something that is recognizable in the traditional notion of ‘ontological’ or ‘strong’ emergence. This understanding is then used to defend the conceptual possibility of such ontological emergence against the influential arguments of Jaegwon Kim. It is further argued that the failure of a different assumption gives rise to a relatively unrecognized form of ontological emergence related to the way that causal influences combine. Thus, an understanding of the reductive method gives us a way to grasp the notoriously slippery metaphysical concept of emergence.

Causal Influence

This chapter argues that the reductive method of explanation assumes an ontology of causal powers that manifest invariant causal influence. The reductive method takes what we know about how systems behave in one situation (typically a situation of relative isolation), and apply that knowledge to explain or predict the behaviour of the system in another situation (such as when it is a part of a more complex system). If this method is to work, then there must be something that remains constant from one situation to another in a way that supports the method. It is shown that standard ontologies do not contain anything that can fulfil this role. It is then shown that a relatively novel kind of entity, dubbed ‘causal influence’, can do the job.

Taking Apart the World

This chapter develops a characterization of the kind of reductive explanation that is the topic of the book. In particular, the book is concerned with substantive causal reductions rather than Nagel-style theory reductions. The characterization of reductive explanation that is developed here is based on Marie Kaiser’s account of explanatory reduction in biology, and, like Kaiser’s account, it highlights the importance of the fact that reductive explanations treat component systems as if they were parts in isolation. That is, in a reductive explanation it is assumed that our knowledge of how an element behaves in isolation can be useful in understanding the role that part plays when it is part of a complex system.

Introduction

This introductory chapter sets out the aim of this book: to investigate the metaphysical assumptions that underlie a pattern of ‘reductive explanation’ whereby we attempt to explain or predict the behaviour of a complex system by studying the system’s parts in isolation. It is argued that the success of reductive explanation is evidence for the truth of these metaphysical assumptions, and it is suggested that the ontology assumed by reduction can be put to use to shed light on the metaphysics of powers, causation, causal models, laws, emergence, and even normative ethics. This task is taken up in the remainder of the book.

Putting Things Together

This chapter brings together the discussions of the previous chapters in order to develop a model of reductive explanation that clarifies the role of causal powers and causal influences, and identifies a number of metaphysical assumptions made by the method of reductive explanation. These assumptions are metaphysical in the sense that they bear on issues of traditional concern to metaphysicians. In so far as the model presented here is an accurate account of how reductive explanation works, the great success of the reductive approach will be evidence for the truth of these presuppositions, and so will give us an empirical handle on various metaphysical questions. The presuppositions unearthed in this chapter will inform the metaphysical picture that is developed in subsequent chapters.

Causal Power

This chapter investigates the ontology of causal power and causal influence that was suggested by the discussion of reductive explanation in the previous two chapters. In particular, it is suggested that we should understand causal powers to be dispositions to manifest causal influence. Such powers, it is shown, can be given a conditional analysis that is less susceptible to counterexamples than conditional analyses of dispositions more generally. It is further argued that the conditional analysis can be extended to cover multi-track powers by using functions, rather than conditionals, to describe powers. Functional descriptions of powers connect nicely to the descriptions of force fields that one finds in physics, suggesting that we can interpret forces as influences in the sense described here.

Influentialism

This final chapter puts the ontology of power and influence to use beyond metaphysics by suggesting that the concept of causal influence may be helpful in the field of normative ethics. In particular, it is argued that the ontology of causal influence opens up the possibility of a novel category of normative ethical theory called influentialism. Influentialism stands in contrast to the traditional categories of consequentialism, deontology, and virtue ethics. The aim is not to argue that influentialism is preferable to these traditional categories, but simply to put the theory on the table for consideration. However, it is argued that influentialism has some promising features that make it worthy of consideration. In particular, influentialism seems to occupy a middle ground between consequentialism and deontology and is able to combine seemingly incompatible intuitions from these two categories.

Causation

This chapter investigates the relation between an ontology of power and influence and the metaphysics of causation. A traditional approach to this task might involve an attempt to provide a conceptual analysis of causation in terms of power and influence, but that is not the approach taken here, for it is argued that there is no single concept of causation. Rather, following Ned Hall, the various concepts of causation are divided into two main camps, causation as production and causation as dependence. In both camps, it is shown, the characteristic features of causation can be generated by the existence of appropriate powers and influences, and questions about whether causation has occurred can be answered, in part, by looking at the arrangement of relevant powers and influences. Thus, it is argued that causation is grounded in structures of causal influence.