James Ladyman

Complexity is heterogenous, involving nonlinearity, self-organisation, diversity, adaptive behaviour, among other things. It is therefore obviously worth asking whether purported measures of complexity measure aggregate phenomena, or individual aspects of complexity and if so which. This paper uses a recently developed rigorous framework for understanding complexity to answer this question about measurement. The approach is two-fold: find measures of individual aspects of complexity on the one hand, and explain measures of complexity on the other. We illustrate the conceptual framework of complexity science and how it links the foundations to the practised science with examples from different scientific fields and of various aspects of complexity. Furthermore, we analyse a selection of purported measures of complexity that have found wide application and explain why and how they measure aspects of complexity. This work gives the reader a tool to take any existing measure of complexity and analyse it, and to take any feature of complexity and find the right measure for it.

Scientism is usually thought of as sinful, but it can be redeemed for our salvation. Scientism should not be dogmatic, nor should it ignore the actual limitations to current science. Other modes of inquiry deserve epistemic respect, and scientists should not be deferred to about matters beyond their expertise. However, limits should not be placed on what science can study and we cannot say in advance what the limits of future science will be. Where science conflicts with common sense, religion, and tradition, it should be regarded as authoritative for the purposes of education and public policy as well as objective inquiry; and scientific knowledge is even relevant to moral and political deliberation. This is the core of scientism. This chapter elaborates a way of thinking of scientism as a stance characterized in terms of positive and negative components and argues for a humane form of scientism.

The positive and negative theses of Ladyman and Ross’s _Every Thing Must Go_ are clarified and defended, and exemplified by how composition is treated in metaphysics and in science. Section 2 provides an apology for the book in two parts, the first presenting the book’s negative content concerning analytic metaphysics, and the second developing its positive metaphysics. Section 3 exemplifies the negative and positive theses of _ETMG_ by criticizing the debate about van Inwagen’s special composition question, and outlining how composition in condensed matter and particle physics is in accord with the real patterns account of existence in which scale relativity and objective modality are central.

The debate about individuality, quantum particles, and the Principle of the Identity of Indiscernibles is discussed. If the definability of identity is at stake, then the cut does not come between individuals and nonindividuals as usually defined, but rather between weakly discernible and completely indiscernible entities. If what is at stake is the principle that identity must be grounded in qualitative properties, even things that are absolutely discernible, in the sense of there being at least one property that one has and not the other, this may only be so in virtue of relational properties. If individuality can be grounded in nonqualitative features of the world, or if a logically thin notion of individuality is adopted, then quantum particles may be individuals after all. It is argued that the metaphysically significant notion of individuality apt for quantum particles is that of “real pattern.”

Mathematical structuralism and structural realism about science both take relations to be irreducible. In this respect they both run counter to the prevailing, or at least prominent, view of many influential metaphysicians that relations are ontologically derivative if not eliminable in favour of individuals and their intrinsic properties. In this chapter some examples of irreducibly relational features of the physical world (including the entangled stated of quantum mechanics) are adduced to motivate structuralism and to provide a naturalistic basis for the metaphysics of relations. Structuralism is often related to the idea that relations can individuate, and to debates about Principle of Identity of Indiscernibles (PII) and the nature and status of individuality. It is argued that popular forms of argument against the grounding of individuality in relations only work if they also work against grounding individuality in non-relational properties.

The paper compares Ladyman and Ross’s version of naturalized metaphysics, Rainforest Realism, with the comprehensive scientific metaphysics recently articulated by a physicist, David Deutsch. Major similarities of the two positions are described and discussed, illustrating the relevance of metaphysics to science. However, a failure of consistent naturalism on Deutsch’s part is also identified and criticized: Deutsch promotes the Everettian multiverse interpretation of quantum physics on the basis of a philosophical commitment to classical determinism. Deutsch also fails to appreciate that a broadly realistic attitude to physical theory does not require denying that some important scientific achievements involve using models and their elements as instruments. Both of these errors are traced to an overly strict dichotomy between pure formalism and empirically interpreted content. In quantum mechanics, Bohr’s version of the Copenhagen interpretation fails to be a fully fledged ‘interpretation’ according to currently dominant philosophical opinion. Ladyman and Ross criticize this opinion. The deep structure of the world is arguably not mathematical but statistical, and there is no such thing as ‘purely formal statistics’. The principles of statistics are generalizations of recurrent patterns found in data; and such structuring of data is the core business of both science and its metaphysical unification. Contrary to Deutsch’s claims, Enlightenment optimism about the capacity for limitless expansion of knowledge is compatible with the hypothesis that the world is irreducibly and fundamentally stochastic. Among great philosophers, C. S. Peirce anticipated this hypothesis. Ladyman and Ross’s metaphysics can be re-described in terms of it, as follows: the world is the totality of non-redundant statistics, not of things.

Ladyman, Presnell, and Short proposed a model of the implementation of logical operations by physical processes in order to clarify the exact statement of Landauer's Principle, and then offered a new proof of the latter based on the construction of a thermodynamic cycle, arguing that if Landauer's Principle were false it would be possible to harness a machine that violated it to produce a violation of the second law of thermodynamics. In a recent paper in this journal, John Norton directly challenges the consistency of that proof. In the present paper we defend the proof given by Ladyman et al. against his critique. In particular, contrary to what Norton claims, we argue that the processes used in the proof cannot be used to construct a cycle that enacts erasure in a thermodynamically reversible way, and that he does not show that the processes used in the proof violate the Second Law of Thermodynamics

Realism about computation is the view that whether or not a particular physical system is performing a particular computation is at least sometimes a mindindependent feature of reality. The caveat ’at least sometimes’ is necessary here because a realist about computation need not believe that all instances of computation should be realistically construed. The computational theory of mind presupposes realism about computation. If whether or not the human nervous system implements particular computations is not a natural fact about the world that is independent of whether we represent it as doing so, then the computational theory of mind fails to naturalise the mind. Realism about computation is also presupposed by attempts to use computational principles such as Landauer’s Principle to dispel Maxwell’s Demon. Realism about computation has been challenged by Hilary Putnam and John Searle among others. Various arguments have been put forward purporting to show that any physical system of sufficient complexity trivially implements all computations. Ladyman et al. offer a precisification and general proof Landauer’s Principle. In order to do this they present an analysis of what it is for a physical process to implement a logical transformation. In this paper, their analysis is explained and its implications for realism about computation and the use of Landauer’s Principle in foundational debates is assessed.

How do we refer to chemical substances, and in particular to chemical elements? This question relates to many philosophical questions, including whether or not theories are incommensurable, the extent to which past theories are later discarded, and issues about scientific realism. This chapter considers the first explicit reference to types of colorless air in late-eighteenth-century chemical practice. Reference to a gas by one chemist was generally intended to give others epistemological, methodological, and practical access to the gas. This chapter proposes a causal-descriptive theory of reference for chemical substances. Implications for debates about incommensurability and realism are also briefly noted.

Interactions between an intelligent software agent and a human user are ubiquitous in everyday situations such as access to information, entertainment, and purchases. In such interactions, the ISA mediates the user’s access to the content, or controls some other aspect of the user experience, and is not designed to be neutral about outcomes of user choices. Like human users, ISAs are driven by goals, make autonomous decisions, and can learn from experience. Using ideas from bounded rationality, we frame these interactions as instances of an ISA whose reward depends on actions performed by the user. Such agents benefit by steering the user’s behaviour towards outcomes that maximise the ISA’s utility, which may or may not be aligned with that of the user. Video games, news recommendation aggregation engines, and fitness trackers can all be instances of this general case. Our analysis facilitates distinguishing various subcases of interaction, as well as second-order effects that might include the possibility for adaptive interfaces to induce behavioural addiction, and/or change in user belief. We present these types of interaction within a conceptual framework, and review current examples of persuasive technologies and the issues that arise from their use. We argue that the nature of the feedback commonly used by learning agents to update their models and subsequent decisions could steer the behaviour of human users away from what benefits them, and in a direction that can undermine autonomy and cause further disparity between actions and goals as exemplified by addictive and compulsive behaviour. We discuss some of the ethical, social and legal implications of this technology and argue that it can sometimes exploit and reinforce weaknesses in human beings.

The Hole Argument is primarily about the meaning of general covariance in general relativity. As such it raises many deep issues about identity in mathematics and physics, the ontology of space–time, and how scientific representation works. This paper is about the application of a new foundational programme in mathematics, namely homotopy type theory, to the Hole Argument. It is argued that the framework of HoTT provides a natural resolution of the Hole Argument. The role of the Univalence Axiom in the treatment of the Hole Argument in HoTT is clarified.

The Univalence axiom, due to Vladimir Voevodsky, is often taken to be one of the most important discoveries arising from the Homotopy Type Theory research programme. It is said by Steve Awodey that Univalence embodies mathematical structuralism, and that Univalence may be regarded as ‘expanding the notion of identity to that of equivalence’. This article explores the conceptual, foundational and philosophical status of Univalence in Homotopy Type Theory. It extends our Types-as-Concepts interpretation of HoTT to Universes, and offers an account of the Univalence axiom in such terms. We consider Awodey’s informal argument that Univalence is motivated by the principle that reasoning should be invariant under isomorphism, and we examine whether an autonomous and rigorous justification along these lines can be given. We consider two problems facing such a justification. First, there is a difference between equivalence and isomorphism and Univalence must be formulated in terms of the former. Second, the argument as presented cannot establish Univalence itself but only a weaker version of it, and must be supplemented by an additional principle. The article argues that the prospects for an autonomous justification of Univalence are promising.

This book argues that the only kind of metaphysics that can contribute to objective knowledge is one based specifically on contemporary science as it really is, and not on philosophers' a priori intuitions, common sense, or simplifications of science. In addition to showing how recent metaphysics has drifted away from connection with all other serious scholarly inquiry as a result of not heeding this restriction, this book demonstrates how to build a metaphysics compatible with current fundamental physics, which, when combined with metaphysics of the special sciences, can be used to unify physics with the other sciences without reducing these sciences to physics itself. Taking science metaphysically seriously, this book argues, means that metaphysicians must abandon the picture of the world as composed of self-subsistent individual objects, and the paradigm of causation as the collision of such objects. The text assesses the role of information theory and complex systems theory in attempts to explain the relationship between the special sciences and physics, treading a middle road between the grand synthesis of thermodynamics and information, and eliminativism about information. The consequences of the books' metaphysical theory for central issues in the philosophy of science are explored, including the implications for the realism versus empiricism debate, the role of causation in scientific explanations, the nature of causation and laws, the status of abstract and virtual objects, and the objective reality of natural kinds.

Social machines are systems formed by technical and human elements interacting in a structured manner. The use of digital platforms as mediators allows large numbers of human participants to join such mechanisms, creating systems where interconnected digital and human components operate as a single machine capable of highly sophisticated behaviour. Under certain conditions, such systems can be described as autonomous and goal-driven agents. Many examples of modern Artificial Intelligence (AI) can be regarded as instances of this class of mechanisms. We argue that this type of autonomous social machines has provided a new paradigm for the design of intelligent systems marking a new phase in the field of AI. The consequences of this observation range from methodological, philosophical to ethical. On the one side, it emphasises the role of Human-Computer Interaction in the design of intelligent systems, while on the other side it draws attention to both the risks for a human being and those for a society relying on mechanisms that are not necessarily controllable. The difficulty by companies in regulating the spread of misinformation, as well as those by authorities to protect task-workers managed by a software infrastructure, could be just some of the effects of this technological paradigm.

The present paper concerns how scientific realism is formulated and defended. It is argued that van Fraassen is fundamentally right that scientific realism requires metaphysics in general, and modality in particular. This is because of several relationships that raise problems for the ontology of scientific realism, namely those between: scientific realism and common sense realism; past and current theories; the sciences of different scales; and the ontologies of the special sciences and fundamental physics. These problems are related. It is argued that ontic structural realism, in the form of the real-patterns account of ontology, offers a unified solution to them all.

This is the second of a pair of papers, of which the first showed how each of the main late phlogistic theories effectively reached impasses due to internal problems or included features which made them unacceptable even to other phlogistians. This paper deals with theory comparison and theory change. It gives an unprecedentedly detailed comparison between the available theories in 1790–1791, and shows that this was overwhelmingly in favour of the new chemistry. This time period correlates well with many chemists changing to the new theory. There was a plurality of views held by individuals and there was freedom of individual choice concerning theories, yet there was also a widespread and rational change to the new chemistry.