Rick Grush

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.

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

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.

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

: 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

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.

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.

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.

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.

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.

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