James Ladyman

This book provides a unified account of models and model-building practice in AI-based science, particularly machine learning (ML). It analyzes the relationship between ML model-building practices and scientific domain knowledge, develops an account of ML models as technical artifacts structured around five levels of abstraction that captures their representational capabilities, and shows how this framework can be used to reformulate contemporary debates in philosophy of science and AI in more fruitful ways.

Philosophers have claimed that: (a) Born–Oppenheimer approximation methods for solving molecular Schrödinger equations violate the Heisenberg uncertainty relations; therefore, (b) ‘quantum chemistry’ is not fully quantum; and (c) therefore chemistry does not reduce to physics. This paper analyses the reasoning behind Born–Oppenheimer methods and shows that they are internally consistent and fully quantum mechanical, contrary to (a)–(c). Our analysis addresses important issues of mathematical rigour, physical idealization, reduction, and classicality in the quantum theory of molecules, and we propose an agenda for the philosophy of quantum chemistry more grounded in scientific practice.

Psillos has recently argued that van Fraassen’s arguments against abduction fail. Moreover, he claimed that, if successful, these arguments would equally undermine van Fraassen’s own constructive empiricism, for, Psillos thinks, it is only by appeal to abduction that constructive empiricism can be saved from issuing in a bald scepticism. We show that Psillos’ criticisms are misguided, and that they are mostly based on misinterpretations of van Fraassen’s arguments. Furthermore, we argue that Psillos’ arguments for his claim that constructive empiricism itself needs abduction point up to his failure to recognize the importance of van Fraassen’s broader epistemology for constructive empiricism. Towards the end of our paper we discuss the suspected relationship between constructive empiricism and scepticism in the light of this broader epistemology, and from a somewhat more general perspective

This paper investigates the formation and propagation of wavefunction `branches' through the process of entanglement with the environment. While this process is a consequence of unitary dynamics, and hence significant to many if not all approaches to quantum theory, it plays a central role in many recent articulations of the Everett or `many worlds' interpretation. A highly idealized model of a locally interacting system and environment is described, and investigated in several situations in which branching occurs, including those involving Bell inequality violating correlations; we illustrate how any non-locality is compatible with the locality of the dynamics. Although branching is particularly important for many worlds quantum theory, we take a neutral stance here, simply tracing out the consequences of a unitary dynamics. The overall goals are to provide a simple concrete realization of the quantum physics of branch formation, and especially to emphasise the compatibility of branching with relativity; the paper is intended to illuminate matters both for foundational work, and for the application of quantum theory to non-isolated systems.

As large language models (LLMs) such as ChatGPT, Claude, Gemini, and Perplexity become increasingly ubiquitous as both tools and objects of scientific study, in addition to their established roles as chatbots, text generators and translators, questions about their identity conditions become scientifically as well as philosophically and socially important. This paper is about how to count language models. We argue that much of the emerging literature on these systems presupposes an answer to the question of identity for these AIs but lacks a framework for counting or individuating them. We propose four levels of analysis, inspired by an analogy with software as well as insights from social epistemology. This account produces practical consequences for both research on language models, the ethics of AI, and our everyday talk about them.

The consensus in philosophy of biology seems to be that although nothing in biological systems is strictly incompatible with physical laws, biology is to a very great extent autonomous from physics. The main thesis of this paper is that, although biology is autonomous from the physical sciences in several ways, it is not explanatorily independent from physics. Physical explanations are pervasive and important in biology, including in evolutionary biology. The paper presents three case studies of physical explanations in evolutionary biology: a case of adaptation to pressure in deep-sea invertebrates, which illustrates how a physical parameter imposes selective pressures that organisms adapt to by changing their own physical properties; the case of water viscosity and the evolution of multicellularity, which shows how a global change in a physical parameter is thought to have triggered a macroevolutionary event; and the case of quantum tunnelling in respiration, which shows how quantum physics is relevant to the evolution of sex in eukaryotes.

Few can imagine a world without telephones or televisions; many depend on computers and the Internet as part of daily life. Without scientific theory, these developments would not have been possible. In this exceptionally clear and engaging introduction to philosophy of science, James Ladyman explores the philosophical questions that arise when we reflect on the nature of the scientific method and the knowledge it produces. He discusses whether fundamental philosophical questions about knowledge and reality might be answered by science, and considers in detail the debate between realists and antirealists about the extent of scientific knowledge. Along the way, central topics in philosophy of science, such as the demarcation of science from non-science, induction, confirmation and falsification, the relationship between theory and observation and relativism are all addressed. Important and complex current debates over underdetermination, inference to the best explaination and the implications of radical theory change are clarified and clearly explained for those new to the subject.

Empiricism is associated with the epistemic privileging of sensory experience. Modern science is based on experiment and observation, but it is highly revisionary of the manifest image, and does not epistemically privilege the human senses. Yet many scientists characterise themselves as empiricists, and many empiricists in philosophy take science to be the ultimate form of rational enquiry. This apparent paradox is resolved by formulating empiricism scientifically so that it epistemically privileges data, not the contents of human sensory experience (sense-data). This scientific way of understanding empiricism maintains its most important positive and negative components, and unifies it with materialism. It also unifies it with ontic structural realism, because scientific empiricism requires a minimal metaphysics of modality.

It is often claimed that biology is autonomous from the physical sciences, but this is seldom made precise. This article makes explicit, for the first time, five distinct “autonomy of biology” theses. Three moderate theses concerning scientific status, methodological distinctness, and nonreducibility of biology to physics are correct and are nearly universally accepted. Two stronger theses, concerning the exclusivity of biological explanation and irrelevance of physical laws, are shown to be false on the basis of two case studies of physical explanations of biological phenomena. Which scales and laws are explanatorily relevant for a particular phenomenon must be decided empirically.

Few can imagine a world without telephones or televisions; many depend on computers and the Internet as part of daily life. Without scientific theory, these developments would not have been possible. In this exceptionally clear and engaging introduction to philosophy of science, James Ladyman explores the philosophical questions that arise when we reflect on the nature of the scientific method and the knowledge it produces. He discusses whether fundamental philosophical questions about knowledge and reality might be answered by science, and considers in detail the debate between realists and antirealists about the extent of scientific knowledge. Along the way, central topics in philosophy of science, such as the demarcation of science from non-science, induction, confirmation and falsification, the relationship between theory and observation and relativism are all addressed. Important and complex current debates over underdetermination, inference to the best explaination and the implications of radical theory change are clarified and clearly explained for those new to the subject.

Three accounts of effective realism (ER) have been advanced to solve three problems for scientific realism: Fraser and Vickers (forthcoming) develop a version of ER about non-relativistic quantum mechanics that they argue is compatible with all the main realist versions (‘interpretations’) of quantum mechanics avoiding the problem of underdetermination among them; Williams (2019) and Fraser (2020b) propose ER about quantum field theory as a response to the problems facing realist interpretations; Robertson and Wilson (forthcoming) propose ER to deal with the dubious ontological status of the entities belonging to superseded theories. This paper argues for the unification of these proposals based on realism about modal structure and the idea of scale relativity of ontology developed by ontic structural realists. This solves problems some or all the accounts of ER face, especially that of making explicit in what way they are realist. Furthermore, we respond to a recent critique that has been raised against the ontic structural realist account of quantum mechanics that we employ.

Questions about the relation between identity and discernibility are important both in philosophy and in model theory. We show how a philosophical question about identity and dis- cernibility can be ‘factorized’ into a philosophical question about the adequacy of a formal language to the description of the world, and a mathematical question about discernibility in this language. We provide formal definitions of various notions of discernibility and offer a complete classification of their logical relations. Some new and surprising facts are proved; for instance, that weak dis- cernibility corresponds to discernibility in a language with constants for every object, and that weak discernibility is the most discerning nontrivial discernibility relation.

This paper designs and defends a conceptual framework for the disambiguation of scientific language regarding open and closed systems. We argue that the open-closed distinction should always be precisifed by specifying a characteristic quantity that is conserved if and only if the system is closed. Open systems are those for which conservation of the characteristic quantity fails. This precisification is in accord with much but not all existing practice. We show that an open system can have well-posed autonomous dynamics and need not be embeddable in any larger system. We distinguish two kinds of autonomy and show that they dissociate from the open-closed distinction. We argue that this framework clears the path towards a new approach to the modelling of autonomous open systems in quantum physics and cosmology.

This paper addresses the question ‘what is an organism?’. Extant theories of organismality only provide a partial answer because they do not include an account of composition on which an ontology of living entities can be based. Here we develop a new account of what organisms are, based on a naturalistic answer to the special composition question, the bound state view. We argue that physical structure, including the existence of a boundary, is essential for life, and that, therefore, organisms are a particular kind of composite physical object – living objects. The bound state account of composition explains how composite physical objects exist in the world, and the property ‘life’ distinguishes the subset of those objects which are organisms. Our view obviates the need for disjunctive accounts of composition for living and non-living entities, placing ‘organism’ within the context of a broader scientific ontology, while at the same time providing a clear criterion of organismality that can be used in adjudicating problematic cases of biological individuality.

This conclusion criticizes Daniel Dennett for dividing reality into first-class illata and second-class abstracta, and argues that fundamental physics directly studies extra-representational real patterns, while special sciences study real patterns located by means of the notional-world concepts of cohesion and causation. Dennett's abstracta are approximate descriptions of the illata, where the approximations in question usefully serve human purposes. By contrast, special-science real patterns are not approximations of (fundamental) physical real patterns. The primacy of physics constraint (PPC) is the only physicalist principle motivated by actual science, and it is too weak to support any form of reduction of special-science real patterns to physical real patterns. The special sciences often successfully track real patterns, an assertion based on the no-miracles argument rather than on any claim about how the special sciences inherit ontological seriousness from their relationship to physics.

This chapter argues that the idea of causation has similar status to ideas of cohesion, forces, and things. Appreciating the role of causation in a notional world is crucial to understanding the nature of the special sciences, and the general ways in which they differ from fundamental physics. Causation, unlike cohesion, is both a notional-world concept and a folk concept. Moreover, causation, unlike cohesion, is a basic category of traditional metaphysics, including metaphysics that purports to be naturalistic but falls short of this ambition. This chapter also argues that causation, just like cohesion, is a representational real pattern that is necessary for an adequately comprehensive science. It begins with an account that eliminates causation altogether on naturalistic grounds, and then shows, using principle of naturalistic closure (PNC)-mandated motivations, why this outright eliminativism is too strong. The eliminativist argument to be discussed is due to Bertrand Russell, whose view has some important contemporary adherents among philosophers of physics.

This chapter argues that a form of structural realism is motivated by reflection on issues that arise in two different domains that have been the subject of intense scrutiny during recent decades. These domains are related to: firstly, problems from the history of science about the abandonment of ontological commitments as old theories which are replaced by more empirically adequate ones; and secondly, questions arising from the debate between scientific realists and constructive empiricists about what really is at stake between them, and about the inadequacies of constructive empiricism. The so-called “semantic” or “model-theoretic” understanding of the nature of scientific representation is suggested to fit very well with the kind of structural realism advocated in this chapter. The structure of the argument presented here is dialectical. The most serious problems for constructive empiricism are explained, and van Fraassen's empiricism is supplemented with a commitment to objective modality to respond to such problems.