Edited Book

Routledge Handbook of Philosophy of Animal Minds (w/ Kristin Andrews)
Routledge, 2017

A collection of nearly 50 original chapters addressing the mental lives of animals. Covered topics include: whether and how animals represent and reason about the world; how animal cognition differs from human cognition; whether animals are conscious; whether animals represent their own mental states or those of others; how animals communicate; the extent to which animals have cultures; how to choose among competing models and explanations of animal behavior; and whether animals are moral agents and/or moral patients.

Academic Articles

Perceptual Noise and the Bell Curve Objection (w/ William Languedoc)
Analysis, forthcoming

Perceptual experience supports the assignment of confidences in belief — doxastic confidences. To explain this fact, many philosophers appeal to PERCEPTUAL INDETERMINACY, which holds that perceptual content can be more or less determinate. Others instead appeal to PERCEPTUAL CONFIDENCE, which says that perceptual experience supports doxastic confidences because it assigns confidences too. Morrison argues that a primary reason to favour PERCEPTUAL CONFIDENCE is that it is uniquely capable of accounting for bell-shaped doxastic confidence distributions; we call this the bell curve objection to PERCEPTUAL INDETERMINACY. Here we show that two recent defences of PERCEPTUAL INDETERMINACY, due to Nanay and Raleigh and Vindrola, fail to adequately address the bell curve objection. But we also argue that all is not lost for proponents of PERCEPTUAL INDETERMINACY. They can counter the bell curve objection by embracing a third view, which we call PERCEPTUAL NOISE. 

The distinction between perception and cognition frames countless debates in philosophy and cognitive science. But what, if anything, does this distinction actually amount to? In this introductory article, we summarize recent work on this question. We first briefly consider the possibility that a perception-cognition border should be eliminated from our scientific ontology, and then introduce and critically examine five positive approaches to marking a perception–cognition border, framed in terms of phenomenology, revisability, modularity, format, and stimulus-dependence.

Contents and Vehicles in Analog Perception
Crítica. Revista Hispanoamericana de Filosofía, 2023

Building on Christopher Peacocke’s account of analog perceptual content and my own account of analog perceptual vehicles, I defend three claims: that the perception of magnitudes often has analog contents; that the perception of magnitudes often has analog vehicles; and that the first claim is true in virtue of the second—that is, the analog vehicles help to ground the analog contents. 

Relationalism maintains that mind-independent objects are essential constituents of veridical perceptual experiences. According to the argument from hallucination, relationalism is undermined by perfect hallucinations, experiences that are introspectively indistinguishable from veridical perceptual experiences but lack an object. Recently, a new wave of relationalists have responded by questioning whether perfect hallucinations are possible: what seem to be perfect hallucinations may really be something else, such as illusions, veridical experiences of non-obvious objects, or experiences that are not genuinely possible. This paper argues that however well new wave relationalism may handle brains in vats, drug users “seeing” pink elephants, and other extraordinary hallucinations, it struggles to accommodate mundane hallucinations, such as “hearing” your child cry out from the room down the hall when she is actually sound asleep or “feeling” vibrations on your thigh even when your phone isn’t in your pocket. Mundane hallucinations are best explained as byproducts of noise in the perceptual system, and noise-induced hallucinations are resistant to the strategies that new wave relationalists deploy to explain away other hallucinations. Mundane hallucinations can thus underpin an especially powerful version of the argument from hallucination.

Numbers, Numerosities, and New Directions (w/ Sam Clarke)
Behavioral and Brain Sciences, 2021
This is our reply to the peer commentaries to our target article, “The Number Sense Represents Rational Numbers.” 

In our target article, we argued that the number sense represents natural and rational numbers. Here, we respond to the 26 commentaries we received, highlighting new directions for empirical and theoretical research. We discuss two background assumptions, arguments against the number sense, whether the approximate number system (ANS) represents numbers or numerosities, and why the ANS represents rational (but not irrational) numbers.

The Number Sense Represents (Rational) Numbers (w/ Sam Clarke)
Behavioral and Brain Sciences, 2021
This target article was published alongside 26 peer commentaries and our reply. 

On a now orthodox view, humans and many other animals possess a “number sense,” or approximate number system (ANS), that represents number. Recently, this orthodox view has been subject to numerous critiques that question whether the ANS genuinely represents number. We distinguish three lines of critique—the arguments from congruency, confounds, and imprecision—and show that none succeed. We then provide positive reasons to think that the ANS genuinely represents numbers, and not just non-numerical confounds or exotic substitutes for number, such as “numerosities” or “quanticals,” as critics propose. In so doing, we raise a neglected question: numbers of what kind? Proponents of the orthodox view have been remarkably coy on this issue. But this is unsatisfactory since the predictions of the orthodox view, including the situations in which the ANS is expected to succeed or fail, turn on the kind(s) of number being represented. In response, we propose that the ANS represents not only natural numbers (e.g. 7), but also non-natural rational numbers (e.g. 3.5). It does not represent irrational numbers (e.g. √2), however, and thereby fails to represent the real numbers more generally. This distances our proposal from existing conjectures, refines our understanding of the ANS, and paves the way for future research.

This article and the surrounding debate were covered (in German) in Die Zeit and on Swiss National Radio.

John Morrison has argued that confidences are assigned in perceptual experience. For example, when you perceive a figure in the distance, your experience might assign a 55-percent confidence to the figure’s being Isaac. Morrison’s argument leans on the phenomenon of ‘completely trusting your experience’. I argue that Morrison presupposes a problematic ‘importation model’ of this familiar phenomenon, and propose a very different way of thinking about it. At issue are not only whether confidences are assigned in perceptual experience, but also, and more generally, how we can determine which properties are assigned in perceptual experience, and how we should understand transitions from perception to belief.

Perception Is Analog: The Argument from Weber’s Law
The Journal of Philosophy, 2019
An early version of this paper was co-winner of the 2017 Antwerp Centre for Philosophical Psychology Essay Prize 

In the 1980s, a number of philosophers argued that perception is analog. In the ensuing years, these arguments were forcefully criticized, leaving the thesis in doubt. This paper draws on Weber’s Law, a well-entrenched finding from psychophysics, to advance a new argument that perception is analog. This new argument is an adaptation of an argument that cognitive scientists have leveraged in support of the contention that primitive numerical representations are analog. But the argument here is extended to the representation of non-numerical magnitudes, such as luminance and distance, and shown to apply to perception and not just cognition. The relevant sense of ‘analog’ is also clarified, and two powerful objections are addressed. Finally, the question whether perception’s analog vehicles are located in conscious experience is explored and related to a well-known controversy within psychophysics.  

Analog Mental Representation
WIRES Cognitive Science
, 2018

Over the past 50 years, philosophers and psychologists have perennially argued for the existence of analog mental representations of one type or another. This study critically reviews a number of these arguments as they pertain to three different types of mental representation: perceptual representations, imagery representations, and numerosity representations. Along the way, careful consideration is given to the meaning of “analog” presupposed by these arguments, and to open avenues for future research.

Philosophy, scientific psychology, and common sense all distinguish perception from cognition. While there is little agreement about how the perception–cognition boundary ought to be drawn, one prominent idea is that perceptual states are dependent on a stimulus, or stimulus-dependent, in a way that cognitive states are not. This paper seeks to develop this idea in a way that can accommodate two apparent counterexamples: hallucinations, which are prima facie perceptual yet stimulus-independent; and demonstrative thoughts, which are prima facie cognitive yet stimulus-dependent. The payoff is not only a specific proposal for marking the perception–cognition boundary, but also a deeper understanding of the natures of hallucination and demonstrative thought.

Attention and Mental Primer (w/ Keith Schneider)
Mind & Language, 2017

Drawing on the empirical premise that attention makes objects look more intense (bigger, faster, higher in contrast), Ned Block has argued for mental paint, a phenomenal residue that cannot be reduced to what is perceived or represented. If sound, Block’s argument would undermine direct realism and representationism, two widely held views about the nature of conscious perception. We argue that Block’s argument fails because the empirical premise it is based upon is false. Attending to an object alters its salience, but not its perceived intensity. We also argue that salience should be equated with mental primer, a close cousin of mental paint that reintroduces difficulties for direct realism and representationism. The upshot is that direct realism and representationism are still in trouble, but not for the reason that Block thinks.

Here is a popular writeup summarizing the gist of the article.

Do Nonhuman Animals Have a Language of Thought?
Routledge Handbook of Philosophy of Animal Minds, 2017

Because we humans speak a public language, there has always been a special reason to suppose that we have a language of thought. For nonhuman animals, this special reason is missing, and the issue is less straightforward. On the one hand, there is evidence of various types of nonlinguistic representations, such as analog magnitude representations, which can explain many types of intelligent behavior. But on the other hand, the mere fact that some aspects of animal cognition can be explained by nonlinguistic representations hardly suffices to show that animal minds are bereft of any sentence-like representations. This paper explores these complexities and argues that empirical research into the logical abilities of nonhuman animals provides a more direct way of evaluating whether they have a language of thought. Along the way, I offer a novel suggestion of how the hypothesis that animals draw disjunctive syllogisms can be empirically distinguished from the hypothesis, defended by Michael Rescorla, that animals reason probabilistically in accordance with Bayes’ Law.
Susan Carey’s account of Quinean bootstrapping has been heavily criticized. While it purports to explain how important new concepts are learned, many commentators complain that it is unclear just what bootstrapping is supposed to be or how it is supposed to work. Others allege that bootstrapping falls prey to the circularity challenge: it cannot explain how new concepts are learned without presupposing that learners already have those very concepts. Drawing on discussions of concept learning from the philosophical literature, this article develops a detailed interpretation of bootstrapping that can answer the circularity challenge. The key to this interpretation is the recognition of computational constraints, both internal and external to the mind, which can endow empty symbols with new conceptual roles and thus new contents.

Analogue Magnitude Representations: A Philosophical Introduction
British Journal for the Philosophy of Science, 2015

Empirical discussions of mental representation appeal to a wide variety of representational kinds. Some of these kinds, such as the sentential representations underlying language use and the pictorial representations of visual imagery, are thoroughly familiar to philosophers. Others have received almost no philosophical attention at all. Included in this latter category are analogue magnitude representations, which enable a wide range of organisms to primitively represent spatial, temporal, numerical, and related magnitudes. This paper aims to introduce analogue magnitude representations to a philosophical audience by rehearsing empirical evidence for their existence and analysing their format, their content, and the computations they support.

I reply to comments by David Miguel Gray and Grant Gillett concerning my paper, “The Generality Constraint and the Structure of Thought”. Their comments are available here and here.

Sense, Mentalese, and Ontology
, 30: Concepts: Contemporary & Historical Perspectives, 2013

Modes of presentation are often posited to accommodate Frege’s puzzle. Philosophers differ, however, in whether they follow Frege in identifying modes of presentation with Fregean senses, or instead take them to be formally individuated symbols of “Mentalese”. Building on Fodor, Margolis and Laurence defend the latter view by arguing that the mind-independence of Fregean senses renders them ontologically suspect in a way that Mentalese symbols are not. This paper shows how Fregeans can withstand this objection. Along the way, a clearer understanding emerges of what senses must be to serve as an ontologically benign alternative to symbols of Mentalese.

Why We Can’t Say What Animals Think
Philosophical Psychology, 2013

Realists about animal cognition confront a puzzle. If animals have real, contentful cognitive states, why can’t anyone say precisely what the contents of those states are? I consider several possible resolutions to this puzzle that are open to realists, and argue that the best of these is likely to appeal to differences in the format of animal cognition and human language.
According to the Generality Constraint, mental states with conceptual content must be capable of recombining in certain systematic ways. Drawing on empirical evidence from cognitive science, I argue that so-called analog magnitude states violate this recombinability condition and thus have nonconceptual content. I further argue that this result has two significant consequences: it demonstrates that nonconceptual content seeps beyond perception and infiltrates cognition; and it shows that whether mental states have nonconceptual content is largely an empirical matter determined by the structure of the neural representations underlying them.

Do Animals Engage in Conceptual Thought?
Philosophy Compass, 2012

This paper surveys and evaluates the answers that philosophers and animal researchers have given to two questions. Do animals have thoughts? If so, are their thoughts conceptual? Along the way, special attention is paid to distinguish debates of substance from mere battles over terminology, and to isolate fruitful areas for future research.

Shorter Academic Pieces

I summarize and critically review Block’s book, focusing on his format-based account of the border between perception and cognition and his new argument for the phenomenal overflow of color perception.

I critically review Peacocke’s book, focusing especially on his account of analog representation, computation, and content.

Some Worries about the ‘No-Overflow’ Interpretation of Post- Stimulus Cueing Experiments
Mind & Language Symposium at the Brains Blog
, June 12, 2017

I comment on Steven Gross and Jonathan Flombaum’s article, “Does Perceptual Consciousness Overflow Cognitive Access? The Challenge from Probabilistic, Hierarchical Processes.” Be sure to also see Robert Briscoe’s general overview, Nico Orlandi and Aaron Franklin’s commentary, Ian Phillips’ commentary, and Gross and Flombaum’s replies.

Atomism about Concepts
Sage Reference Encyclopedia of the Mind, 2013

An encyclopedia entry introducing concept atomism, the view that most lexical concepts are primitive.

Pop Pieces

Born to Count (w/ Sam Clarke)
Scientific American, March 2023

We review scientific evidence for an innate number sense and locate it relative to philosophical accounts of mathematics and the mind.  

Can We Really Know What Animals Are Thinking?
The Conversation, September 5, 2019

Reflecting on the life of Sarah, a chimpanzee who served as a research subject for most of her life, I argue that our ability to understand animal thought is subject to principled limitations.

Translated into French for La Conversation: Peut-on réellement savoir à quoi pensent les animaux?

Translated into Arabic for Popular Science Arabia: هل من الممكن أن تفكّر الحيوانات كما نفكّر حقاً؟

My live radio interview about this piece on the Jill Bennett Show (starting around 17:10)

I review six bad arguments for banning performance-enhancing drugs from sports — and a seventh good one.