Rick Grush

The nature of temporal experience is typically explained in one of a small number of ways, most are versions of either retentionalism or extensionalism. After describing these, I make a distinction between two kinds of temporal character that could structure temporal experience: A-ish contents are those that present events as structured in past/present/future terms, and B-ish contents are those that present events as structured in earlier-than/later-than/simultaneous-with relations. There are a few exceptions, but most of the literature ignores this distinction, and silently assumes temporal experience is A-ish. I then argue that temporal character is not scale invariant, but rather that temporal experience is A-ish at larger scales, and B-ish at smaller scales. I then point out that this scale non-invariance opens the possibility of hybrid views. I clarify my own view as a hybrid view, according to which temporal experience is B-ish at small scales – and at this scale my trajectory estimation model applies – but A-ish at larger scales, and at the larger scale my TEM does not apply. I then motivate this hybrid position by first defending it against arguments that have tried to show that the TEM is untenable. Since the hybrid view has TEM as its small-scale component, it must address this objection. I then put pressure on the main alternative account, extentionalism, by showing that its proponents have not adequately dealt with the problem of temporal illusions. The result is a new theory motivated by i) explaining its virtues, ii) showing that objections to it can be met, and iii) showing that objections to its main competitors have not been met.

This paper is largely exegetical/interpretive. My goal is to demonstrate that some criticisms that have been leveled against the program Gareth Evans constructs in The Varieties of Reference (Evans 1980, henceforth VR) misfire because they are based on misunderstandings of Evans’ position. First I will be discussing three criticisms raised by Tyler Burge (Burge, 2010). The first has to do with Evans’ arguments to the effect that a causal connection between a belief and an object is insufficient for that belief to be about that object. A key part of Evans’ argument is to carefully distinguish considerations relevant to the semantics of language from considerations relevant to the semantics (so to speak) of thought or belief (to make the subsequent discussion easier, I will henceforth use ‘thought’ as a blanket term for the relevant mental states, including belief). I will argue that Burge’s criticisms depend on largely not taking account of Evans’ distinctions. Second, Burge criticizes Evans’ account of ‘informational content’ taking it to be inconsistent. I will show that the inconsistency Burge finds depends entirely on a misreading of the doctrine. Finally, Burge takes Evans to task for a perceived over-intellectualization in a key aspect of his doctrine. Burge incorrectly reads Evans as requiring that the subject holding a belief be engaged in certain overly intellectual endeavors, when in fact Evans is only attributing these endeavors to theorists of such a subject. Next, I turn to two criticisms leveled by John Campbell (Campbell, 1999). I will argue that Campbell’s criticisms are based on misunderstandings – though they do hit at deeper elements of Evans’ doctrine. First, Campbell reads Evans’ account of demonstrative thought as requiring that the subject’s information link to an object allows her to directly locate that object in space. Campbell constructs a case in which one tomato (a) is, because of an angled mirror, incorrectly seen as being at a location that happens to be occupied by an identical tomato (b). Campbell claims that Evans’ doctrines require us to conclude that the subject cannot have a demonstrative thought about the seen tomato (a), though it seems intuitively that such a subject would be able to have a demonstrative thought about that tomato, despite its location is inaccurately seen. I show that Evans’ position in fact allows that the subject can have a demonstrative thought about the causal-source tomato in this case because his account does not require that the location of demonstratively identified objects be immediately accurately assessed. What is crucial is that the subject have the ability to accurately discover the location. Second, Campbell criticizes Evans’ notion of a fundamental level of thought. I show that this criticism hinges on view of the nature and role of the fundamental level of thought that mischaracterizes Evans’ treatment of the notion.

I have argued elsewhere that imagery and represention are best explained as the result of operations of neurally implemented emulators of an agent's body and environment. In this article I extend the theory of emulation to address perceptual processing as well. The key notion will be that of an emulator of an agent's egocentric behavioral space. This emulator, when run off-line, produces mental imagery, including transformations such as visual image rotations. However, while on-line, it is used to process information from sensory systems, resulting in perception (in this regard, the theory is similar to that proposed by Kosslyn (1994)). This emulator is what provides the theory in theory-laden perception. I close by arguing briefly that the spatial character of perception is to be explained as the contribution of the egocentric behavioral space emulator

The emulation theory of representation is developed and explored as a framework that can revealingly synthesize a wide variety of representational functions of the brain. The framework is based on constructs from control theory (forward models) and signal processing (Kalman filters). The idea is that in addition to simply engaging with the body and environment, the brain constructs neural circuits that act as models of the body and environment. During overt sensorimotor engagement, these models are driven by efference copies in parallel with the body and environment, in order to provide expectations of the sensory feedback, and to enhance and process sensory information. These models can also be run off-line in order to produce imagery, estimate outcomes of different actions, and evaluate and develop motor plans. The framework is initially developed within the context of motor control, where it has been shown that inner models running in parallel with the body can reduce the effects of feedback delay problems. The same mechanisms can account for motor imagery as the off-line driving of the emulator via efference copies. The framework is extended to account for visual imagery as the off-line driving of an emulator of the motor-visual loop. I also show how such systems can provide for amodal spatial imagery. Perception, including visual perception, results from such models being used to form expectations of, and to interpret, sensory input. I close by briefly outlining other cognitive functions that might also be synthesized within this framework, including reasoning, theory of mind phenomena, and language. Key Words: efference copies; emulation theory of representation; forward models; Kalman filters; motor control; motor imagery; perception; visual imagery

In this article I explore a number of questions that have not been adequately investigated in philosophy of mind circles: are minds located in the same place as the brains (or other computing machinery) supporting them? Must they exist at the same location as the body? Must they exist at the same time? Could a single mind be implemented in multiple brains, or multiple minds in a single brain? Under what conditions might a single mind persist despite being implemented successively in different brains? What contributions do features of the computing machinery make to these questions, compared to the contribution made by the body and embedded point of view? Some of these questions have been touched on previously, but there hasn’t been any attempt at a systematic analysis of the various consequences that different approaches in the philosophy of mind have for how the spatiotemporal location, synchronic individuation and diachronic identity of minds relates to the spatiotemporal location, synchronic individuation, and diachronic identity of both the implementing computational machinery and the embodied embedded point of view. I make a first stab at such an analysis by discussing a variety of thought experiments in which such questions of location, individuation, and identity arise, and I explore how various approaches to understanding the mind – identity theoretic, functionalist, contentualist, embodied/embedded/extended, and so forth – would respond to such situations. A number of novel issues emerge, and some surprising affinities are revealed.

There is a definite challenge in the air regarding the pivotal notion of internal representation. This challenge is explicit in, e.g., van Gelder, 1995; Beer, 1995; Thelen & Smith, 1994; Wheeler, 1994; and elsewhere. We think it is a challenge that can be met and that (importantly) can be met by arguing from within a general framework that accepts many of the basic premises of the work (in new robotics and in dynamical systems theory) that motivates such scepticism in the first place. Our strategy will be as follows. We begin (Section 1) by offering an account (an example and something close to a definition) of what we shall term Minimal Robust Representationalism (MRR). Sections 2 & 3 address some likely worries and questions about this notion. We end (Section 4) by making explicit the conditions under which, on our account, a science (e.g., robot- ics) may claim to be addressing cognitive phenomena

An attempt is made to defend a general approach to the spatial content of perception, an approach according to which perception is imbued with spatial content in virtue of certain kinds of connections between perceiving organism's sensory input and its behavioral output. The most important aspect of the defense involves clearly distinguishing two kinds of perceptuo-behavioral skills—the formation of dispositions, and a capacity for emulation. The former, the formation of dispositions, is argued to by the central pivot of spatial content. I provide a neural information processing interpretation of what these dispositions amount to, and describe how dispositions, so understood, are an obvious implementation of Gareth Evans' proposal on the topic. Furthermore, I describe what sorts of contribution are made by emulation mechanisms, and I also describe exactly how the emulation framework differs from similar but distinct notions with which it is often unhelpfully confused, such as sensorimotor contingencies and forward models

Using the Godel incompleteness result for leverage, Roger Penrose has argued that the mechanism for consciousness involves quantum gravitational phenomena, acting through microtubules in neurons. We show that this hypothesis is implausible. First the Godel result does not imply that human thought is in fact non-algorithmic. Second, whether or not non-algorithmic quantum gravitational phenomena actually exist, and if they did how that could conceivably implicate microtubules, and if microtubules were involved, how that could conceivably implicate consciousness, is entirely speculative. Third, cytoplasmic ions such as calcium and sodium are almost certainly present in the microtubule pore, barring the quantum-mechanical effects Penrose envisages. Finally, physiological evidence indicates that consciousness does not directly depend on microtubule properties in any case, rendering doubtful any theory according to which consciousness is generated in the microtubules

b>: The problem of how physical systems, such as brains, come to represent themselves as subjects in an objective world is addressed. I develop an account of the requirements for this ability that draws on and refines work in a philosophical tradition that runs from Kant through Peter Strawson to Gareth Evans. The basic idea is that the ability to represent oneself as a subject in a world whose existence is independent of oneself involves the ability to represent space, and in particular, to represent oneself as one object among others in an objective spatial realm. In parallel, I provide an account of how this ability, and the mechanisms that support it, are realized neurobiologically. This aspect of the article draws on, and refines, work done in the neurobiology and psychology of egocentric and allocentric spatial representation

b>: In this article I outline, apply, and defend a theory of natural representation. The main consequences of this theory are: i) representational status is a matter of how physical entities are used, and specifically is not a matter of causation, nomic relations with the intentional object, or information; ii) there are genuine (brain-)internal representations; iii) such representations are really representations, and not just farcical pseudo-representations, such as attractors, principal components, state-space partitions, or what-have-you;and iv) the theory allows us to sharply distinguish those complex behaviors which are genuinely cognitive from those which are merely complex and adaptive

I examine one of the conceptual cornerstones of the field known as computational neuroscience, especially as articulated in Churchland et al. (1990), an article that is arguably the locus classicus of this term and its meaning. The authors of that article try, but I claim ultimately fail, to mark off the enterprise of computational neuroscience as an interdisciplinary approach to understanding the cognitive, information-processing functions of the brain. The failure is a result of the fact that the authors provide no principled means to distinguish the study of neural systems as genuinely computational/information-processing from the study of any complex causal process. I then argue for two things. First, that in order to appropriately mark off computational neuroscience, one must be able to assign a semantics to the states over which an attempt to provide a computational explanation is made. Second, I show that neither of the two most popular ways of trying to effect such content assignation -- informational semantics and 'biosemantics' -- can make the required distinction, at least not in a way that a computational neuroscientist should be happy about. The moral of the story as I take it is not a negative one to the effect that computational neuroscience is in principle incapable of doing what it wants to do. Rather, it is to point out some work that remains to be done

Nothing is more obvious than the fact that we are able to experience events in the world such a ball deflecting from the cross-bar of a goal. But what is the temporal relation between these two things, the event, and our experience of the event? One possibility is that the world progresses temporally through a sequence of instantaneous states – the striker’s foot in contact with the ball, then the ball between the striker and the goal, then the ball in contact with the cross-bar, and so forth –, while the perceiver’s experience is likewise a sequence of experience states, each one of which corresponds to, or is experience of, a corresponding state of the world – for example, a perception of the foot in contact with the ball, followed by a perception of the ball in the air, following by a perception of the ball in contact with the cross-bar. This way of understanding the relationship between experience and the world is very natural, and nearly universal. However, it rests on two assumptions that can be brought into question.

: Berkeley's Essay Towards a New Theory of Vision presents a theory of various aspects of the spatial content of visual experience that attempts to undercut not only the optico-geometric accounts of e.g., Descartes and Malebranche, but also elements of the empiricist account of Locke. My task in this paper is to shed light on some features of Berkeley's account that have not been adequately appreciated. After rehearsing a more detailed Lockean critique of the notion that depth is a proper object of vision, Berkeley directs arguments he takes to be entirely parallel against the notion that vision has two-dimensional planar contents as proper objects. I show that this argument fails due to an illicit slide unnoticed by both Berkeley and his commentators—a slide present but innocuously so in the case of depth. Berkeley's positive account, according to which the apparent spatial content of vision is a matter of associations between, on the one hand, tactile and motor contents, and on the other hand non-spatial visual contents, also fails because of an illicit slide—again, unnoticed by Berkeley and his commentators. I close by discerning the salvageable and correct core of Berkeley's theory of the spatiality of vision

Philosophy interfaces with cognitive science in three distinct but related areas. First, there is the usual set of issues that fall under the heading of philosophy of science (explanation, reduction, etc.), applied to the special case of cognitive science. Second, there is the endeavor of taking results from cognitive science as bearing upon traditional philosophical questions about the mind, such as the nature of mental representation, consciousness, free will, perception, emotions, memory, etc. Third

  I argue against a growing radical trend in current theoretical cognitive science that moves from the premises of embedded cognition, embodied cognition, dynamical systems theory and/or situated robotics to conclusions either to the effect that the mind is not in the brain or that cognition does not require representation, or both. I unearth the considerations at the foundation of this view: Haugeland's bandwidth-component argument to the effect that the brain is not a component in cognitive activity, and arguments inspired by dynamical systems theory and situated robotics to the effect that cognitive activity does not involve representations. Both of these strands depend not only on a shift of emphasis from higher cognitive functions to things like sensorimotor processes, but also depend on a certain understanding of how sensorimotor processes are implemented - as closed-loop control systems. I describe a much more sophisticated model of sensorimotor processing that is not only more powerful and robust than simple closed-loop control, but for which there is great evidence that it is implemented in the nervous system. The is the emulation theory of representation, according to which the brain constructs inner dynamical models, or emulators, of the body and environment which are used in parallel with the body and environment to enhance motor control and perception and to provide faster feedback during motor processes, and can be run off-line to produce imagery and evaluate sensorimotor counterfactuals. I then show that the emulation framework is immune to the radical arguments, and makes apparent why the brain is a component in the cognitive activity, and exactly what the representations are in sensorimotor control

Two very different insights motivate characterizing the brain as a computer. One depends on mathematical theory that defines computability in a highly abstract sense. Here the foundational idea is that of a Turing machine. Not an actual machine, the Turing machine is really a conceptual way of making the point that any well-defined function could be executed, step by step, according to simple 'if-you-are-in-state-P-and-have-input-Q-then-do-R' rules, given enough time (maybe infinite time) [see COMPUTATION]. Insofar as the brain is a device whose input and output can be characterized in terms of some mathematical function -- however complicated -- then in that very abstract sense, it can be mimicked by a Turning machine. Given what is known so far brains do seem to depend on cause-effect operations, and hence brains appear to be, in some formal sense, equivalent to a Turing machine [see CHURCH-TURING THESIS]. On its own, however, this reveals nothing at all of how the mind-brain actually works. The second insight depends on looking at the brain as a biological device that processes information from the environment to build complex representations that enable the brain to make predictions and select advantageous behaviors. Where necessary to avoid ambiguity, we will refer to the first notion of computation as.

The question of whether time is its own best representation is explored. Though there is theoretical debate between proponents of internal models and embedded cognition proponents (e.g. Brooks R 1991 Artificial Intelligence 47 139–59) concerning whether the world is its own best model, proponents of internal models are often content to let time be its own best representation. This happens via the time update of the model that simply allows the model’s state to evolve along with the state of the modeled domain. I argue that this is neither necessary nor advisable. I show that this is not necessary by describing how internal modeling approaches can be generalized to schemes that explicitly represent time by maintaining trajectory estimates rather than state estimates. Though there are a variety of ways this could be done, I illustrate the proposal with a scheme that combines filtering, smoothing and prediction to maintain an estimate of the modeled domain’s trajectory over time. I show that letting time be its own representation is not advisable by showing how trajectory estimation schemes can provide accounts of temporal illusions, such as apparent motion, that pose serious difficulties for any scheme that lets time be its own representation.

I explain a strategy, called model-based control, which has proven useful in control theory, and argue that many aspects of brain function can be understood as applications of this strategy. I first demonstrate that in the domain of motor control, there is good evidence that the brain constructs models, or emulators, of musculoskeletal dynamics. I then argue that imagery, motor, visual and otherwise, can be supported by these emulatory mechanisms. I argue that the same apparatus to understanding aspects of psychological development, including the development of theory of mind. I then show how features of linguistic competence can be addressed with the same mechanisms. Finally, I develop a semantic theory applicable to these emulators

0. Introduction The past decade has seen Cognitive Linguistics (CL) emerge as an important, exciting and promising theoretical alternative to Chomskyan approaches to the study of language. Even so, sheer numbers and institutional inertia make it the case that most current neurolinguistic research either assumes that the Chomskyan formalist story is more or less correct (and thus that the task of neurolinguistics is to determine how the brain implements GB, for instance), or that the there are two possibilities, Chomskyanism or associationism/connectionism, and that the task of neurolinguistics is to discover which is really the way the brain does it. In either case, the theoretical apparatus of CL is not being explored by neurolinguistics, and hence the promise CL holds for making genuine fruitful contact with theoretical neurobiology is not materializing as quickly as one might hope. This paper is an attempt to make some initial steps at fulfilling this promise.

Two very different insights motivate characterizing the brain as a computer. One depends on mathematical theory that defines computability in a highly abstract sense. Here the foundational idea is that of a Turing machine. Not an actual machine, the Turing machine is really a conceptual way of making the point that any well-defined function could be executed, step by step, according to simple 'if-you-are-in-state-P-and-have-input-Q-then-do-R' rules, given enough time (maybe infinite time) [see COMPUTATION]. Insofar as the brain is a device whose input and output can be characterized in terms of some mathematical function -- however complicated -- then in that very abstract sense, it can be mimicked by a Turning machine. Given what is known so far brains do seem to depend on cause-effect operations, and hence brains appear to be, in some formal sense, equivalent to a Turing machine [see CHURCH-TURING THESIS]. On its own, however, this reveals nothing at all of how the mind-brain actually works. The second insight depends on looking at the brain as a biological device that processes information from the environment to build complex representations that enable the brain to make predictions and select advantageous behaviors. Where necessary to avoid ambiguity, we will refer to the first notion of computation as algorithmic computation, and the second as information processing computation.

Enaction, as put forward by Varela and defended by other thinkers (notably Alva Noë, 2004; Susan Hurley, 2006; and Kevin O’Regan, 1992), departs from traditional accounts that treat mental processes (like perception, reasoning, and action) as discrete, independent processes that are causally related in a sequen- tial fashion. According to the main claim of the enactive approach, which Thompson seems to fully endorse, perceptual awareness is taken to be a skill-based activity. Our perceptual contact with the world, according to the enactionists, is not mediated by representations but is enacted, and the notion of representation, belonging to the classic computational paradigm, has no place in this alternative approach. Though Thompson does not pronounce directly on the issue of representationalism, he is most definitely keeping the company of anti-representationalists, and in that context it is not unreasonable to take his silence for consent. In this paper, we will argue that the enactive approach to imagery is unworkable unless it makes appeal to representations, understood in a particular way. Not understood as pictures, to be sure. Or sentences for that matter. But those aren’t the only options.

The emulation theory of representation articulated in the target article is further explained and explored in this response to commentaries. Major topics include: the irrelevance of equilibrium-point and related models of motor control to the theory; clarification of the particular sense of “representation” which the emulation theory of representation is an account of; the relation between the emulation framework and Kalman filtering; and addressing the empirical data considered to be in conflict with the emulation theory. In addition, I discuss the further empirical support for the emulation theory provided by some commentators, as well as a number of suggested theoretical applications.

[1] It is well-known that Evans laid the groundwork for a truly radical and fruitful theory of _content_ -- a theory according to which content is a genus with at least conceptual and nonconceptual varieties as species, and in which nonconceptual content plays a very significant role. It is less well-recognized that Evans was also in the process of working out the details of a truly radical and groundbreaking theory of _representation_, a task he was unfortunately unable to bring to any satisfactory stage of fruition. I am here drawing the distinction between a theory of

Sensory Individuals: Unimodal and Multimodal Perspectives provides an interdisciplinary, well-balanced, and comprehensive look at different aspects of unisensory and multisensory objects, using both nuanced philosophical analysis and informed empirical work. The research presented in this book represents the field's progression from treating neural sensory processes as primarily modality-specific towards its current state of the art, according to which perception, and its supporting neural processes, are multi-modal, modality-independent, meta-modal, and task-dependent. Even within such approaches sensory stimuli, properties, brain activations, and corresponding perceptual phenomenology can still be characterized in a modality-specific way. The book examines the basic building blocks of human perception, and whether they are best understood as sense modality dependent units of different forms or multimodal perceptual objects. The book combines a variety of innovative and integrative angles to explore the topic and acts as a catalyst for an increasingly diverse field of research, which is in an exciting phase of growth and advancement. New questions are arising as quickly as they are being answered, and the collection Sensory Individuals provides an original and up-to-date addition to the field.