Recent attempts to turn Standard Quantum Theory into a coherent representational system have improved markedly over previous offerings. Important questions about the nature of material systems remain open, however, as current theorizing effectively resolves into a multiplicity of incompatible statements about the nature of physical systems. Specifically, the most cogent proposals to date land in effective empirical equivalence, reviving old anti-realist fears about quantum physics. In this paper such fears are discussed and found unsound. It is argued that nothing of global skeptical or agnostic significance follows from the kind of underdetermination presently encountered in fundamental quantum theory. The case is instructive, however, for what it shows about the characteristics and prospects of scientific realism as a perspective in contemporary philosophy of science.
Recent attempts to turn Standard Quantum Theory into a coherent representational system have improved markedly over previous offerings. Important questions about the nature of material systems remain open, however, as current theorizing effectively resolves into a multiplicity of incompatible statements about the nature of physical systems. Specifically, the most cogent proposals to date land in effective empirical equivalence, reviving old anti-realist fears about quantum physics. In this paper such fears are discussed and found unsound. It is argued that nothing of global skeptical or agnostic significance follows from the kind of underdetermination presently encountered in fundamental quantum theory. The case is instructive, however, for what it shows about the characteristics and prospects of scientific realism as a perspective in contemporary philosophy of science.
Scientific realism has traditionally maintained that our best scientific theories can be regarded as more or less true and as representing the world as it is (more or less). However, one of our very best current theories—quantum mechanics—has famously resisted such a realist construal, threatening to undermine the realist stance altogether. The chapters in this volume carefully examine this tension and the reasons behind it, including the underdetermination generated by the multiplicity of formulations and interpretations of quantum physics, each presenting a different way the world could be. Authors in this volume offer a range of alternative ways forward: some suggest new articulations of realism, limiting our commitments in one way or another; others attempt to articulate a ‘third way’ between traditional forms of realism and antirealism, or are critical of such attempts. Still others argue that quantum theory itself should be reconceptualised, or at least alternative formulations should be considered in the hope of evading the problems faced by realism. And some examine the nature of these issues when moving beyond quantum mechanics to quantum field theory. Taken together they offer an exciting new set of perspectives on one of the most fundamental questions in the philosophy of modern physics: how can one be a realist about quantum theory, and what does this realism amount to?
Much has been discussed in the philosophy of science about how we should understand the scientific enterprise. On the one hand, scientific realists believe that empirically adequate theories can be supplemented by interpretations that can mirror reality-as-it-is; on the other hand, anti-realists argue that this is not the case, as long as scientific theories make sufficiently accurate experimental predictions the addition of narratives is irrelevant for the scientific enterprise, and regarding narratives, it is preferable to remain agnostic. In this paper, we argue that realism was never really at stake in this debate.
Impressively successful at the empirical level and open to multiple interpretations at the theoretical domain, quantum theory provides a rich source of examples of underdetermination. A more promising line of support for realism about quantum mechanics emerges from experimental physics. Some significant experiments have been conducted that prima facie seem to lead to very natural realist readings. The author first considers the challenge these experiments seem to raise to current forms of empiricism, particularly constructive empiricism. Three arguments are examined: the experiments challenge an important form of underdetermination employed by empiricists; the nature of quantum particles, in particular their identity and individuality, seems unproblematic in the context of these experiments, and the experiments provide an unprecedented form of access to the quantum particles involved. The discussion of an empiricist response to these three arguments is shaped by questions regarding the identity, individuality, and individuation of quantum particles in experimental contexts.
Scientific realists often say that there should be belief in the approximate truth of ‘our best scientific theories.’ It is hard to hear the phrase ‘our best scientific theories’ without thinking of quantum mechanics and quantum field theories. But as numerous chapters in this collection make clear, it is unclear that some experts even know how to make sense of being a realist about quantum theories. They provide recipes for calculating incredibly precise predictions for observations, but beyond the recipes, they do not seem to offer a clear-cut or unambiguous picture of what physical reality is like at the fundamental level. After giving an overview of the problems that beset any attempt to believe in the truth or approximate truth of quantum theories, Chapter 2 turns to the question of how to protect scientific realism from the ills of the quantum. The aim is to show that it is possible to quarantine the worst of those ills, freeing us to adopt a robustly realistic attitude toward many other extremely successful areas of contemporary science, such as (parts of) geology, microbiology, and chemistry. The quarantine barrier may be imperfect and permeable in places, but is strong enough (the chapter argues) to help the cause of scientific realism.
Quantum theory is a tremendously successful physical theory, but nevertheless suffers from two serious problems: the measurement problem and the problem of interpretational underdetermination. The latter, however, is largely overlooked as a genuine problem of its own. Both problems concern the doctrine of realism, but pull, quite curiously, into opposite directions. The measurement problem can be captured such that due to scientific realism about quantum theory common sense anti-realism follows, while theory underdetermination usually counts as an argument against scientific realism. I will also consider the more refined distinctions of ontic and epistemic realism and demonstrate that quantum theory in its most viable interpretations conflicts with at least one of the various realism claims. A way out of the conundrum is to come to the bold conclusion that quantum theory is, possibly, wrong (in the realist sense).
According to scientific realism, science gives us an approximately true description of what the world is like. But what does it mean? In this chapter, we focus on the ontological and metaphysical aspects of this discussion. That is, we are concerned with the following questions: what there is, according to our best scientific theories? And how are these things that theories say exist? We start from the assumption that a genuine scientific realism must deal with these issues. Taking non-relativistic quantum mechanics as a case study, we discuss some of the challenges currently faced by a genuinely realistic stance. We argue, first, that in the ontological aspect, realists are in the same boat as science, that is, without sufficient epistemic justification to adopt the belief in the entities postulated by a single quantum theory, given that experience (currently) is not able to decide between rival theories; in the metaphysical aspect, realists also encounter problems with theory choice, given the possibility of associating more than one metaphysical theory with the description of the entities postulated by each quantum theory. The same goes for structuralist alternatives, since, even if we accept that scientific theories are committed to the existence of structures, but not objects, we still do not know what structures are, metaphysically. Finally, we move forward in the discussion with the meta-Popperian method, which serves to reduce the metaphysical alternatives associated with the ontological postulates of scientific theories. We may not know what the correct alternative is, but we have been able to progressively check which metaphysical alternatives are incompatible with each scientific theory.