Jenann Ismael

Quantum mechanics seems to portray nature as nonseparable, in the sense that it allows spatiotemporally separated entities to have states that cannot be fully specified without reference to each other. This is often said to implicate some form of “holism.” We aim to clarify what this means, and why this seems plausible. Our core idea is that the best explanation for nonseparability is a “common ground” explanation, which casts nonseparable entities in a holistic light, as scattered reflections of a more unified underlying reality.

In a famous passage drawing implications from determinism, Laplace introduced the image an intelligence who knew the positions and momenta of all of the particles of which the universe is composed, and asserted that in a deterministic universe such an intelligence would be able to predict everything that happens over its entire history. It is not, however, difficult to establish the physical possibility of a counterpredictive device, i.e., a device designed to act counter to any revealed prediction of its behavior. What would happen if a Laplacean intelligence were put into communication with such a device and forced to reveal its prediction of what the device would do on some occasion? On the one hand, it seems that the Laplacean Intelligence should be able to predict the device's behavior. On the other hand, it seems like that device should be able to act counter to the prediction. An examination of the puzzle leads to clarification of what determinism does entail, with some insights about various other things along the way.

On April 1, 2016, at the Annual Meeting of the Pacific Division of the American Philosophical Association, a book symposium, organized by Alyssa Ney, was held in honor of David Albert’s After Physics. All participants agreed that it was a valuable and enlightening session. We have decided that it would be useful, for those who weren’t present, to make our remarks publicly available. Please bear in mind that what follows are remarks prepared for the session, and that on some points participants may have changed their minds in light of the ensuing discussion.

In 1687 Isaac Newton ushered in a new scientific era in which laws of nature could be used to predict the movements of matter with almost perfect precision. Newton's physics also posed a profound challenge to our self-understanding, however, for the very same laws that keep airplanes in the air and rivers flowing downhill tell us that it is in principle possible to predict what each of us will do every second of our entire lives, given the early conditions of the universe. Can it really be that even while you toss and turn late at night in the throes of an important decision and it seems like the scales of fate hang in the balance, that your decision is a foregone conclusion? Can it really be that everything you have done and everything you ever will do is determined by facts that were in place long before you were born? This problem is one of the staples of philosophical discussion. It is discussed by everyone from freshman in their first philosophy class, to theoretical physicists in bars after conferences. And yet there is no topic that remains more unsettling, and less well understood. If you want to get behind the façade, past the bare statement of determinism, and really try to understand what physics is telling us in its own terms, read this book. The problem of free will raises all kinds of questions. What does it mean to make a decision, and what does it mean to say that our actions are determined? What are laws of nature? What are causes? What sorts of things are we, when viewed through the lenses of physics, and how do we fit into the natural order? Ismael provides a deeply informed account of what physics tells us about ourselves. The result is a vision that is abstract, alien, illuminating, and-Ismael argues-affirmative of most of what we all believe about our own freedom. Written in a jargon-free style, How Physics Makes Us Free provides an accessible and innovative take on a central question of human existence.

The intuitive difference between a system that choreographs the motion of its parts in the service of goals of its own formulation and a system composed of a collection of parts doing their own thing without coordination has been shaken by now familiar examples of self-organization. There is a broad and growing presumption in parts of philosophy and across the sciences that the appearance of centralized information-processing and control in the service of system-wide goals is mere appearance, i.e., an explanatory heuristic we have evolved to predict behavior, but one that will eventually get swept away in the advancing tide of self-organization. I argue that there is a distinction of central importance here, and that no adequate science of complex systems can dispense with it

The role of probability is one of the most contested issues in the interpretation of contemporary physics. In this paper, I’ll be reevaluating some widely held assumptions about where and how probabilities arise. Larry Sklar voices the conventional wisdom about probability in classical physics in a piece in the Stanford Online Encyclopedia of Philosophy, when he writes that “Statistical mechanics was the first foundational physical theory in which probabilistic concepts and probabilistic explanation played a fundamental role.” And the conventional wisdom about quantum probabilities is that they are basic, not reducible to the types of probabilities we see in statistical mechanics. In the first section of this paper, I’ll argue that in fact classical physics was steeped in probability long before statistical mechanics came on the scene, specifically, that an objective measure over phase space is an indispensable component of any informative physical theory. In the next section, I’ll argue that this objective measure is the fundamental form of physical probability and that quantum probabilities can be defined in terms of it. In the last, I’ll raise some questions about the metaphysical status of the fundamental measure

For most of the major philosophers of the seventeenth and eighteenth centuries, human cognition was understood as involving the mind’s reflexive grasp of its own contents. But other important figures have described the very idea of a reflexive thought as incoherent. Ryle notably likened the idea of a reflexive thought to an arm that grasps itself. Recent work in philosophy, psychology, and the cognitive sciences has greatly clarified the special epistemic and semantic properties of reflexive thought. This article is an attempt to give an explicit characterization of the structure of reflexive thoughts that explains those properties and avoids the complaints of its critics

The chance of a physical event is the objective, single-case probability that it will occur. In probabilistic physical theories like quantum mechanics, the chances of physical events play the formal role that the values of physical quantities play in classical physics, and there is a temptation to regard them on the model of the latter as describing intrinsic properties of the systems to which they are assigned. I argue that this understanding of chances in quantum mechanics, despite being a part of the orthodox interpretation of the theory and the most prevalent view in the physical community, is incompatible with a very wide range of metaphysical views about the nature of chance. The options that remain are unlikely to be attractive to scientists and scientifically minded philosophers.

The most potentially powerful objection to the possibility oftime travel stems from the fact that it can, under the right conditions, give rise to closedcausal loops, and closed causal loops can be turned into self-defeating causal chains;folks killing their infant selves, setting out to destroy the world before they were born,and the like. It used to be thought that such chains present paradoxes; the receivedwisdom nowadays is that they give rise to physical anomalies in the form of inexplicably correlated events. I argue against the received wisdom. I can find nothing in them that argues against the possibility (even, the probability) of time travel.

Quantum mechanics seems to portray nature as nonseparable, in the sense that it allows spatiotemporally separated entities to have states that cannot be fully specified without reference to each other. This is often said to implicate some form of “holism.” We aim to clarify what this means, and why this seems plausible. Our core idea is that the best explanation for nonseparability is a “common ground” explanation, which casts nonseparable entities in a holistic light, as scattered reflections of a more unified underlying reality.

In the general project of trying to reconcile the subjective view of the world (how things seem from the perspective of the embedded agent) with the objective view (the view of the world from the outside, as represented, for example, in our best physics), analytic philosophy, especially in recent years, has been almost solely focused on sensory phenomenology.1 There are two very salient features of the subjective view that haven’t been explored even on the descriptive side but that present prima facie problems at least as great as sensory phenomenology. One is agential phenomenology (the experience of ourselves as agents in the world), and the other is temporal phenomenology. 2 The problems presented by these cases are very different. I want to focus on temporal phenomenology, by which I mean the felt character of a life lived in time. And my goal here is mostly descriptive; I’ll be exploring the question of what it is like to be the kind of being that has a history, that experiences that history in stages, and that keeps a running record of that history as it unfolds. 3 My suggestion is going to be that there is a special phenomenology, not supervenient on the sensory phenomenology, that arises only in the representational setting created by autobiographical memory and that is central to the felt character of a life lived in time. 4 (by autobiographical memory here, I mean not simply what is sometimes referred to as episodic memory - mental images of past experiences - I mean an explicit, account of one’s own history, rendered in explicitly first-personal form. (the difference here is the difference between a perspectival representation centered on the self of the sort that visual experience gives us and an explicit representation of self, of the sort you have, for example when you translate visual experience into a first personal belief like “I am such and such a place, seeing such and such”)..

First para: Before the 17th century, there was not much discussion, and little uniformity in conception, of natural laws. The rise of science in 17th century, Newton’s mathematization of physics, and the provision of strict, deterministic laws that applied equally to the heavens and to the terrestrial realm had a profound impact in transforming the philosophical imagination. A philosophical conception of physical law built on the example of Newtonian Mechanics became quickly entrenched. Between the 17th and 20th centuries, there was a great deal of philosophical interest in probabilities, but probabilities were mostly regarded as having something to do with the management of opinion, not as having a fundamental role in science. Probabilities made their first appearance in an evidently ineliminable way in the laws of a fundamental theory with the advent of quantum mechanics. Quantum probabilities have come to be called ‘chances’ in the philosophical literature, and their interpretation has been one of the central problems in philosophy of science now for almost a century. There continue to be hold-outs that insist that there must be an underlying probability-free replacement for quantum mechanics and Bohmians have had some success in formulating a deterministic alternative to quantum mechanics, but most physicists accept that the probabilistic character of the quantum mechanical laws is likely to be retained in any successor theory. While physics has adjusted itself comfortably to the existence of ineliminably probabilistic laws, philosophy has not managed arrive at a stable interpretation of quantum probability. The difficulty is that there are a number of constraints that an interpretation of chance must satisfy, constraints that appear to be partially definitive of the concept and it proves to be extraordinarily difficult to meet them simultaneously.

I want to consider some features of the position put forward by Julian Barbour in The End of Time that seem to me of particular philosophical interest. At the level of generality at which I'll be concerned with it, the view is relatively easy to describe. It can be arrived at by thinking of time as decomposing in some natural way linearly ordered atomic parts, ‘moments’, and combining an observation about the internal structure of moments with an epistemological doctrine about our access to the past. The epistemological doctrine, which I'll call ‘Presentism’, following Butterfield, is the view that our access to the past is mediated by records, or local representations, of it. The observation is that the state of the world at any moment has the structure of what Barbour calls a ‘time capsule’, which is to say that it constitutes a partial record of its past, it is pregnant with interrelated mutually consistent representations of its own history.

The intuitive notion of cause carries with it the idea of compulsion. When we learn that the dynamical laws are deterministic, we give this a causal reading and imagine our actions compelled to occur by conditions laid down at the beginning of the universe. Hume famously argued that this idea of compulsion is borrowed from experience and illegitimately projected onto regularities in the world. Exploiting the interventionist analysis of causal relations, together with an insight about the degeneracy of one’s epistemic relations to one’s own actions, I defend a Humean position with regard to the idea of causal compulsion. Although I discuss only compulsion, a similar story could be told about the temporal directedness of causation.

Human beings think of themselves in terms of a privileged non-descriptive designator — a mental “I”. Such thoughts are called “_de se_” thoughts. The mind/body problem is the problem of deciding what kind of thing I am, and it can be regarded as arising from the fact that we think of ourselves non-descriptively. Why do we think of ourselves in this way? We investigate the functional role of “I” (and also “here” and “now”) in cognition, arguing that the use of such non-descriptive “reflexive” designators is essential for making sophisticated cognition work in a general-purpose cognitive agent. If we were to build a robot capable of similar cognitive tasks as humans, it would have to be equipped with such designators

This chapter addresses the worry that the existence of causal antecedents to your choices means that you are causally compelled to act as you do. It begins with the folk notion of cause, leads the reader through recent developments in the scientific understanding of causal concepts, and argues that those developments undermine the threat from causal antecedents. The discussion is then used as a model for a kind of naturalistic metaphysics that takes its lead from science, letting everyday concepts be shaped and transformed by scientific developments.

Quantum mechanics is, at least at first glance and at least in part, a mathematical machine for predicting the behaviors of microscopic particles — or, at least, of the measuring instruments we use to explore those behaviors — and in that capacity, it is spectacularly successful: in terms of power and precision, head and shoulders above any theory we have ever had. Mathematically, the theory is well understood; we know what its parts are, how they are put together, and why, in the mechanical sense (i.e., in a sense that can be answered by describing the internal grinding of gear against gear), the whole thing performs the way it does, how the information that gets fed in at one end is converted into what comes out the other. The question of what kind of a world it describes, however, is controversial; there is very little agreement, among physicists and among philosophers, about what the world is like according to quantum mechanics. Minimally interpreted, the theory describes a set of facts about the way the microscopic world impinges on the macroscopic one, how it affects our measuring instruments, described in everyday language or the language of classical mechanics. Disagreement centers on the question of what a microscopic world, which affects our apparatuses in the prescribed manner, is, or even could be, like intrinsically ; or how those apparatuses could themselves be built out of microscopic parts of the sort the theory describes.[1..