Papers and Projects

The gist of the many-subjects argument is that, given physicalism, it’s hard to avoid the absurd result that there are many conscious subjects in your vicinity with more-or-less the same experiences as you. The most promising ways of avoiding this result have a consequence almost as bad: that there are many things in your vicinity that are in a state only trivially different from being conscious, a state with similar normative significance. This paper clarifies and defends three versions of the many-subjects argument. One version poses the threat of conscious parts. Its key premise is that if physicalism is true, then not only you, but also certain parts of your body, are conscious. These parts might include your brain, your head, all-of-you-except-your-left-pinky, all-of-your-brain-except-one-neuron, or your left cerebral hemisphere. A second version poses the threat of conscious coinciders, things that currently occupy the same spatial region as you and share all your matter. Its key premise is that if physicalism is true, then not only you, but also some things that currently coincide with you, are conscious. These might include your body or the aggregate of particles of which you are currently composed. A third version poses the threat of conscious person candidates, the many human-body-shaped material objects in your vicinity that mostly overlap one another, differing only in a few peripheral atoms. This version claims that if physicalism is true, then there are many conscious person-candidates in your vicinity.

Moral realism faces a well known genealogical debunking challenge. I argue that the moral realist’s best response may involve abandoning metaphysical naturalism in favor of some form of axiarchism—the view, very roughly, that the natural world is “ordered to the good.” Axiarchism comes in both theistic and non-theistic forms, but all forms agree that the natural world exists and has certain basic features because it is good for it to exist and have those features. I argue that theistic and non-theistic forms of axiarchism are better positioned than metaphysical naturalism to avoid two commitments that a moral realist should seek to avoid: that the correctness of our moral beliefs is a major coincidence, and that there is a complete explanation of our moral beliefs that does not mention any moral truths.

Our universe features a harmonious match between laws and states: applying its laws to its states generates other states.  This is a striking fact. Matters might have been otherwise.  The universe might have been stillborn in a state unengaged by its laws.  The problem of nomological harmony is that of explaining the noted striking fact.   After introducing and developing this problem, we canvass candidate solutions and identify some of their virtues and vices.  Candidate solutions invoke the likes of a designer, axiarchic meta-laws, multiverses, essential causal powers, and Humean laws.

According to a traditional view of the afterlife, God causes or allows some people to go to hell after death, where hell is understood as a place, state, or condition that involves everlasting suffering. This view—call it "traditionalism"—faces a well-known proportionality objection.  If we regard the suffering of the damned as a punishment, traditionalism seems to imply that some receive an infinite punishment. But no one’s earthly deeds merit an infinite punishment, and God does not punish unjustly, so (the objection concludes) traditionalism is false. This paper develops two lines of response to the proportionality objection, both of which challenge the assumption that traditionalism implies that some receive an infinite punishment. There are at least two reasons why a punishment involving everlasting suffering need not be an infinitely severe punishment. First, everlasting suffering doesn’t entail infinite suffering. Moreover, there are theologically attractive models that combine everlasting suffering with finite total suffering. Second, infinite suffering wouldn’t entail infinite negative well-being, even if the suffering isn’t counterbalanced by positive experiences, and even if there are no relevant non-hedonic contributors to well-being. I show that the inference from infinite suffering to infinite negative well-being should be rejected by anyone who rejects Parfit’s “repugnant conclusion” in its single-life form.

According to the AI ensoulment hypothesis, some future AI systems will be endowed with immaterial souls. I argue that we should have at least a middling credence in the AI ensoulment hypothesis, conditional on our eventual creation of AGI and the truth of substance dualism in the human case. I offer two arguments, the alien analogy argument and the fitting recipient argument. The first relies on an analogy between aliens and AI. If we met seemingly intelligent aliens that resemble us abstractly in behavioral and functional respects but differ from us in material composition, it would be unreasonable to dismiss the hypothesis that they have souls, provided we do. And if we shouldn’t dismiss the alien ensoulment hypothesis, neither should we dismiss the AI ensoulment hypothesis, for the cases are closely analogous. The fitting recipient argument rests on the claim that, if substance dualism is true, it is reasonable to conjecture that ensoulment occurs whenever a physical system is “fit to possess” a soul, where very roughly this amounts to being physically structured in such a way that the system can meaningfully cooperate with the operations of the soul. It is then argued that being fit to possess a soul depends only on a system’s behavioral capacities and functional organization. Since the human body is fit to possess a soul, a functionally human-like AI would be as well.

This commentary on Adam Pautz's excellent book, Perception, explores the consequences of "spatial illusionism," the view that the spatial properties presented in experience aren't instantiated in the extra-mental world. First, I consider whether spatial illusionism entails that our ordinary beliefs about the physical world are mostly false. I then argue that spatial illusionism threatens to undermine two arguments Pautz defends in Perception: his argument that sense data theory is incompatible with physicalism, and his central argument against the internal physical state view of perception.

This paper develops a new argument from consciousness to theism: the argument from psychophysical harmony. Roughly, psychophysical harmony consists in the fact that phenomenal states are correlated with physical states and with one another in strikingly fortunate ways. For example, phenomenal states are correlated with behavior and functioning that is justified or rationalized by those very phenomenal states, and phenomenal states are correlated with verbal reports and judgments that are made true by those very phenomenal states. We argue that psychophysical harmony is strong evidence for theism (or, at least, strong evidence against atheism in its standard naturalistic form).

According to a familiar modern view, color and other so-called secondary qualities reside only in consciousness, not in the external physical world. Many have argued that this “Galilean” view is the source of the mind-body problem in its current form. This paper critically examines a radical alternative to the Galilean view, which has recently been defended or sympathetically discussed by several philosophers, a view I call “anti-modernism.” Anti-modernism holds, roughly, that the modern Galilean scientific image is incomplete – in particular, it leaves out certain irreducible qualitative properties, such as colors – and that we can solve (or dissolve) the hard problem of consciousness by accepting these properties as objective features of the external physical world. I argue, first, that anti-modernism cannot fulfill its promise. Even if the outer world is resplendent with primitive colors, color experience remains a mystery. Second, I argue that the theoretical costs of accepting irreducible colors in the world are enormous. Even if irreducible colors in the world could dispel the mysteries surrounding consciousness, the theoretical benefit would not be worth the costs. If the problems of consciousness and color require that we posit irreducible properties somewhere, it would be far more plausible to accept irreducible phenomenal properties on the side of the subject, and to reject irreducible colors on the side of the object.

This paper develops and defends a new argument against physicalist views of consciousness: the inconceivability argument. The argument has two main premises. First, it is not (ideally, positively) conceivable that phenomenal truths are grounded in physical truths. (For example, one cannot positively conceive of a situation in which someone has a vivid experience of pink wholly in virtue of the movements of colorless, insentient atoms.) Second, (ideal, positive) inconceivability is a guide to falsity. I attempt to show that the inconceivability argument enjoys a significant advantage over the more familiar conceivability argument. One can reasonably endorse the inconceivability argument without endorsing the conceivability argument, but one cannot reasonably endorse the conceivability argument without also endorsing the inconceivability argument. 

Perceptual illusionism is the view that perceptual experience is, in general, radically illusory. That is, perceptual experience presents objects as having certain sensible properties and standing in certain sensible relations, but nothing in the subject’s environment has those properties or stands in those relations. This paper makes the case for perceptual illusionism by showing how a broad set of philosophical and scientific considerations converge to support illusionism about the full range of sensible properties and relations. After clarifying the illusionist thesis, I set out the argument in three parts. First, I briefly make the case for an illusionist view of color. I then argue for illusionism about the spatial/temporal properties presented in experience on the assumption that some “radical” view of space (and/or time) is correct—that is, some view according to which nothing like our ordinary three-dimensional space (or four-dimensional spacetime) exists at the fundamental level. Finally, I argue that there is a strong case for illusionism even if all radical views turn out to be false.

It is common for an object to present different color appearances to different perceivers, even when the perceivers and viewing conditions are normal. For example, a Munsell chip might look unique green to you and yellowish green to me in normal viewing conditions. In such cases, there are three possibilities. Ecumenism: Both experiences are veridical. Nihilism: Both experiences are non-veridical. Inegalitarianism: One experience is veridical and the other is non-veridical. Perhaps the most important objection to inegalitarianism is the ignorance objection, according to which inegalitarianism should be rejected because it is committed to the existence of unknowable color facts (e.g., facts about which objects are unique green). The goal of this paper is to show that ecumenists are also committed to unknowable color facts. More specifically, I argue that, with the exception of color eliminativism, all major philosophical theories of color are committed to unknowable color facts.

Imagine your mirror-inverted counterpart on Mirror Earth, a perfect mirror image of Earth. Would her experiences be the same as yours, or would they be phenomenally mirror-inverted? I argue, first, that her experiences would be phenomenally the same as yours. I then show that this conclusion gives rise to a puzzle, one that I believe pushes us toward some surprising and philosophically significant conclusions about the nature of perception. When you have a typical visual experience as of something to your left, the following three claims seem very plausible: (1) No one could have an experience phenomenally just like yours without thereby having an experience as of something to her left. (2) Your experience is veridical. (3) Your experience doesn’t differ from that of your mirror-inverted counterpart with respect to veridicality. But (1)-(3) jointly contradict the claim that you and your mirror-inverted counterpart would have the same experiences. I argue that any viable response to this puzzle will embrace the following disjunction: either there is a degree of independence between perceptual phenomenology and representational content, contrary to popular intentionalist views of perception, or spatial subjectivism is true, where spatial subjectivism is the view that the spatial properties presented in perception are either mind-dependent or illusory.

The modal argument against materialism, in its most standard form, relies on a compatibility thesis to the effect that the physical truths are compatible with the absence of consciousness. I propose an alternative modal argument that relies instead on an incompatibility thesis: the existence of consciousness is incompatible with the claim that the physical truths provide (in a sense to be clarified) a complete description of reality. I show that the revised modal argument is strictly superior to the standard modal argument in the following sense: Everyone who endorses the premises of the standard modal argument must endorse the premises of the revised modal argument, but not vice versa. More specifically, I show that there are a number of anti-materialist views, including reasonable versions of idealism, Russellian monism, interactionist dualism, and theism, that are inconsistent with the modal premise of the standard modal argument but consistent with the premises of the revised argument. Those who accept such views, or are merely unwilling to rule them out, can therefore accept the revised modal argument, but not the standard modal argument.

Some truths about color are knowable a priori. For example, it is knowable a priori that redness is not identical to the property of being square. This extremely modest and plausible claim has significant philosophical implications, or so I shall argue. First, I show that this claim entails the falsity of standard forms of color functionalism, the view that our color concepts are functional concepts that pick out their referents by way of functional descriptions that make reference to the subjective responses of perceivers. I then argue that, while some sophisticated forms of color functionalism can accommodate the a priori knowability of a truth like “redness is not identical to squareness,” they can only do so by abandoning color realism, the thesis that colors are instantiated by external material objects. In practice, color functionalists are almost invariably color realists. Thus, given extremely modest assumptions concerning what can be known a priori about color, we should conclude that color functionalism, at least in its typical realist form, is false.

This paper argues that nearly every proposition could in principle be known a priori, with exceptions for necessary falsehoods and a few other odd cases. The argument for this conclusion has two main premises: (i) Odd exceptions aside, if it is possible that p, then it is possible that someone knows innately that p. (ii) Necessarily, whatever is known innately is known a priori. After defending (i) and (ii), I conclude by suggesting that the best way to recover a reasonably limited and interesting conception of the a priori is to adopt an anthropocentric notion of a priori knowability, one that is relativized to our own innate cognitive capacities. However, this proposal has consequences that contradict prevailing views about the a priori. More importantly, this proposal has the result that many philosophical applications of the notion of apriority are misguided. 

One of the most important objections to sense data theory comes from the phenomenon of indeterminate perception, as when an object in the periphery of one’s visual field looks red without looking to have any determinate shade of red. Since sense data are supposed to have precisely the properties that sensibly appear to us, sense data theory evidently has the implausible consequence that a sense datum can have a determinable property without having any of its determinates. In this paper, I show that a parallel objection applies to standard forms of color relationism. In light of the phenomenon of indeterminate perception, the color relationist must either reject intuitively obvious facts about the determinate-determinable structure of color space (e.g., that red is a determinable) or reject the plausible and widely accepted principle that nothing can have a determinable without having one of its determinates.

Russellian monism represents a middle ground between physicalist and dualist views of consciousness, a refuge for those who reject physicalism for the usual reasons but wish to avoid the extravagancies of dualism. I argue that this middle-ground position is unstable. Those who reject physicalism on the basis of the usual epistemic arguments should reject Russellian monism on similar grounds and embrace some form of dualism. Conversely, those unwilling to go all the way to dualism must reject the epistemic arguments against physicalism. In either case, these arguments cannot be used to motivate Russellian monism.

An explanation of why I came to accept Christianity (and then Catholicism specifically) as an adult. Focuses on the philosophical motivations for my conversion.  Written for a popular audience.

Consciousness is morally significant: the overall goodness or badness of a world, or the overall quality of one's life, at least partly depends on the conscious states included in it. I argue that the moral significance of consciousness has ramifications in metaethics and philosophy of mind, placing constraints on which metaethical positions can be combined with which positions on the metaphysics of consciousness. The main conclusion of this paper is that reductive materialism about consciousness is false if robust moral realism is true. The argument for this conclusion proceeds by drawing out a conflict between reductive materialism about consciousness and certain metaethical principles which I argue to be consequences of robust moral realism, including the following (here stated very roughly): (i) The most fundamental moral expressions do not exhibit semantic indeterminacy. (ii) The question of whether a certain moral concept applies to a situation is always a substantive question, never merely a “verbal” question (at least when the question is framed in terms of the most fundamental moral concepts). (iii) The most fundamental moral expressions are semantically stable, in the sense that their meanings are not sensitive to miniscule changes in usage. A secondary conclusion of this paper, then, is that reductive materialism about consciousness is false if any of (i)-(iii) are true. This secondary conclusion is significant apart from its role in establishing my main conclusion, since any of (i)-(iii) could be accepted by someone who rejects robust moral realism.

This paper defends a non-reductive realist view of the sensible qualities---roughly, the view that the sensible qualities are (i) really instantiated by the external objects of perception, and (ii) not reducible to response-independent physical properties or response-dependent relational properties. I begin by clarifying and motivating the non-reductive realist view. I then consider some familiar difficulties for the view. Addressing these difficulties leads to the development and defense of a general theory, inspired by Russellian Monist theories of consciousness, of how the sensible qualities (especially the so-called "secondary qualities") relate to physical reality. I conclude by showing how this theory, which I call “Secondary Quality Russellian Monism,” resolves the most significant difficulties for the non-reductive realist view of the sensible qualities.

The consequence argument is widely regarded as the most important argument for incompatibilism. In this paper, I argue that, although the consequence argument may be sound in its standard formulations, it does not support any thesis that could reasonably be called 'incompatibilism'.

In recent work, David Chalmers argues that “Edenic shapes”—roughly, the shape properties phenomenally presented in spatial experience—are not instantiated in our world. His reasons come largely from Special Relativity. Although Edenic shapes might have been instantiated in a classical Newtonian world, he maintains that they could not be instantiated in a relativistic world like our own. In this essay, I defend realism about Edenic shape (RES), the thesis that Edenic shapes are instantiated in our world, against Chalmers’s challenge from Special Relativity. I begin by clarifying the notion of an Edenic shape by reference to Chalmers’s notion of the “Edenic" (or "presentational") content of perceptual experience. I then reconstruct Chalmers’s argument that Edenic shapes could not be instantiated in a relativistic world. His reasoning proceeds from two assumptions. The first is that the only shape properties instantiated in a relativistic world are those which somehow involve relations to frames of reference. This is thought to follow from the phenomenon of Lorentz contraction, a consequence of Special Relativity. The second assumption is that Edenic shapes do not involve relations to frames of reference. One reason to accept the second assumption is that it seems that Edenic shapes could be instantiated in a classical Newtonian world, where the notion of a frame-relative shape has no meaningful application. I then proceed to defend RES against Chalmers’s argument by arguing that Special Relativity, properly understood, provides no support for Chalmers’s first assumption. More generally, I argue, by way of a careful analysis of the geometric structure of Minkowski space-time (the space-time postulated by Special Relativity) and Galilean space-time (the space-time of (neo-)Newtonian physics), that Edenic shapes are no less at home in a relativistic world than in a classical Newtonian world.

A handbook article summarizing philosophical debates about pain and representation. Does pain have representational content? If so, what does it represent? Does its content fully determine its phenomenal character? Is its content "indicative" or "imperative"?  

Many philosophers, especially in the wake of the 17th century, have favored an inegalitarian view of shape and color, according to which shape is mind-independent while color is mind-dependent. In this essay, I advance a novel argument against inegalitarianism. The argument begins with an intuition about the modal dependence of color on shape, namely: it is impossible for something to have a color without having a shape (i.e. without having some sort of spatial extension, or at least spatial location). I then argue that, given reasonable assumptions, inegalitarianism contradicts this modal-dependence principle. Given the plausibility of the latter, I conclude that we should reject inegalitarianism in favor of some form of egalitarianism—either a subjective egalitarianism on which both shape and color are mind-dependent or an objective egalitarianism on which both shape and color are mind-independent.

In this paper, we defend the representationalist theory of phenomenal consciousness against a recent objection due to Hilla Jacobson, who charges representationalism with a failure to explain the role of pain in rationalizing certain forms of behavior. In rough outline, her objection is that the representationalist is unable to account for the rationality of certain acts, such as the act of taking pain killers, which are aimed at eliminating the experience of pain rather than its intentional object. If representationalism were true, she claims, then the act of taking pain killers would be just as irrational as the act of a ruler who responds to bad tidings by killing the messenger. This paper aims to show that these charges are mistaken.

Representationalism is the thesis that the phenomenal character of an experience supervenes on its representational content. Tracking representationalism is the conjunction of representationalism with a “tracking” or causal-covariation account of the content of experience. Several philosophers have maintained that the experience of pain poses a serious challenge to tracking representationalism. In particular, tracking representationalism is thought to be unable to account for the negative affective quality or “painfulness” of pain. In this paper we defend tracking representationalism against this challenge. We argue that pain has both descriptive and evaluative content and that pain has its negative affective quality in virtue of its (negative) evaluative content. We then show how a tracking theory of experiential content can accommodate this view of the content of pain. We conclude by noting some advantages of our account over a rival representationalist account, which explains the negative affective quality of pain in terms of imperative content rather than evaluative content.