This chapter develops metaphysics to include quantum mechanical realism. Quantum mechanics has always been the main obstacle to acceptance of scientific realism, and hence to any metaphysics based on scientific realism. Realism about Schrdinger waves requires the belief that particles are always transmitted as quantum mechanically indeterminate waves, but always act as classically determinate particles on whatever absorbs them. Acceptance of a realistic theory of Schrdinger waves, and of the very rapid or instantaneous changes of state that quantum theory implies, commits one to the view that all transitions from indeterminate to determinate states are temporally irreversible, apparently in contradiction to the widely accepted T-symmetry thesis. Realism about Schrdinger waves already implies a kind of non-locality, because what was spatially distributed before the event of determination suddenly becomes localized in that event. Quantum realism implies that there is a common species of elementary physical causation that is probabilistic, and directed from one determinate state of affairs to another.
This chapter develops metaphysics to include quantum mechanical realism. Quantum mechanics has always been the main obstacle to acceptance of scientific realism, and hence to any metaphysics based on scientific realism. Realism about Schrdinger waves requires the belief that particles are always transmitted as quantum mechanically indeterminate waves, but always act as classically determinate particles on whatever absorbs them. Acceptance of a realistic theory of Schrdinger waves, and of the very rapid or instantaneous changes of state that quantum theory implies, commits one to the view that all transitions from indeterminate to determinate states are temporally irreversible, apparently in contradiction to the widely accepted T-symmetry thesis. Realism about Schrdinger waves already implies a kind of non-locality, because what was spatially distributed before the event of determination suddenly becomes localized in that event. Quantum realism implies that there is a common species of elementary physical causation that is probabilistic, and directed from one determinate state of affairs to another.
Quantum mechanics has always presented a problem for scientific realists. For it does not seem to offer a coherent picture of the world. I think it does, and that there is a viable quantum mechanical model of reality. But it cannot be constructed, given the continuity constraints that we usually place on realistic models. To be a quantum mechanical realist, one has to be willing to accept that there are two fundamentally different kinds of processes occurring in nature: continuous, but quantum mechanically indeterminate, energy transfer processes and discontinuous, but spatially extended, changes of state. The unwillingness of philosophers to accept that there is such a distinction has caused many of them to doubt the reality of Schrödinger waves, and the processes of their generation and collapse. I am fully aware that I am treading on well-trodden territory, and that the technical difficulties that must be faced by anyone who is not a specialist in the field are immense. Nevertheless, I think there is a fairly clear metaphysical position on these issues derivable from the kind of essentialist realism outlined in the previous chapter, and I ask readers to bear with me. First, realism about Schrödinger waves requires the belief that particles are always transmitted as quantum mechanically indeterminate waves, but always act as classically determinate particles on whatever absorbs them. The probability of absorption by a given absorbing object (e.g. measuring instrument) at a given location is determined by the value of the Ψ-function at this point.
Quantum mechanics has always presented a problem for scientific realists.For it does not seem to offer a coherent picture of the world.I think it does, and that there is a viable quantum mechanical model of reality.But it cannot be constructed, given the continuity constraints that we usually place on realistic models.To be a quantum mechanical realist, one has to be willing to accept that there are two fundamentally different kinds of processes occurring in nature: continuous, but quantum mechanically indeterminate, energy transfer processes and discontinuous, but spatially extended, changes of state.The unwillingness of philosophers to accept that there is such a distinction has caused many of them to doubt the reality of Schrodinger waves, and the processes of their generation and collapse.I am fully aware that I am treading on well-trodden territory, and that the technical difficulties that must be faced by anyone who is not a specialist in the field are immense.Nevertheless, I think there is a fairly clear metaphysical position on these issues derivable from the kind of essentialist realism outlined in the previous chapter, and I ask readers to bear with me.First, realism about Schrodinger waves requires the belief that particles are always transmitted as quantum mechanically indeterminate 1.
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.
Scientific realism is the view that our best scientific theories can be regarded as (approximately) true. This is connected with the view that science, physics in particular, and metaphysics could (and should) inform one another: on the one hand, science tells us what the world is like, and on the other hand, metaphysical principles allow us to select between the various possible theories which are underdetermined by the data. Nonetheless, quantum mechanics has always been regarded as, at best, puzzling, if not contradictory. As such, it has been considered for a long time at odds with scientific realism, and thus a naturalized quantum metaphysics was deemed impossible. Luckily, now we have many quantum theories compatible with a realist interpretation. However, scientific realists assumed that the wave-function, regarded as the principal ingredient of quantum theories, had to represent a physical entity, and because of this they struggled with quantum superpositions. In this paper I discuss a particular approach which makes quantum mechanics compatible with scientific realism without doing that. In this approach, the wave-function does not represent matter which is instead represented by some spatio-temporal entity dubbed the primitive ontology: point-particles, continuous matter fields, space-time events. I argue how within this framework one develops a distinctive theory-construction schema, which allows to perform a more informed theory evaluation by analyzing the various ingredients of the approach and their inter-relations.
Quantum mechanics has seemed to defy all attempts to construe it realistically, but antirealism, like the many‐worlds hypothesis, is even more difficult to accept. In order to give a realist construal of quantum mechanics, we need first to distinguish the objective and rational aspect of reality from the paradigmatic thing‐like aspects of having determinate physical properties: quantum‐mechanical entities may be real in the former sense though not in the latter. Anti‐realist arguments are based on the difficulty of giving an account of quantum‐mechanical collapse and the apparent superluminal velocities involved. Objections to superluminal velocities on the score of the special theory of relativity are found not to be conclusive, and the price—there being some preferred frame of reference—to be acceptable. A sketch of a probabilistic account of quantum‐mechanical collapse is offered, which makes the difference between the macro‐ and the micro‐world a matter of degree rather than kind. If that, or some other, account proved acceptable, we could be quantum‐mechanical realists, though quantum‐mechanical reality would be very different from that of material objects in hardware shops.
Abstract Metaphysicians should pay attention to quantum mechanics, but not because it provides definitive answers to many metaphysical questions. The theory itself is remarkably silent on the nature of the physical world, and the various interpretations of the theory on offer present conflicting ontological pictures. Rather, quantum mechanics is essential to the metaphysician because it reshapes standard metaphysical debates and opens up unforeseen new metaphysical possibilities. Even if quantum mechanics provides few clear answers, there are good reasons to think that any adequate understanding of the quantum world will result in a radical reshaping of our classical worldview in some way or other. Whatever the world is like at the atomic scale, it is almost certainly not the swarm of particles pushed around by forces that is often presupposed. This book guides readers through the theory of quantum mechanics and its implications for metaphysics in a clear and accessible way. The theory and its various interpretations are presented with a minimum of technicality. The consequences of these interpretations for metaphysical debates concerning realism, indeterminacy, causation, determinism, holism, and individuality (among other topics) are explored in detail, stressing the novel form that the debates take given the empirical facts in the quantum domain. While quantum mechanics may not deliver unconditional pronouncements on these issues, the range of possibilities consistent with our knowledge of the empirical world is relatively small—and each possibility is metaphysically revisionary in some way.