David Chalmers

Why is two-dimensional semantics important? One can think of it as the most recent act in a drama involving three of the central concepts of philosophy: meaning, reason, and modality. First, Kant linked reason and modality, by suggesting that what is necessary is knowable a priori, and vice versa. Second, Frege linked reason and meaning, by proposing an aspect of meaning (sense) that is constitutively tied to cognitive signi?cance. Third, Carnap linked meaning and modality, by proposing an aspect of meaning (intension) that is constitutively tied to possibility and necessity

A number of popular arguments for dualism start from a premise about an epistemic gap between physical truths about truths about consciousness, and infer an ontological gap between physical processes and consciousness. Arguments of this sort include the conceivability argument, the knowledge argument, the explanatory-gap argument, and the property dualism argument. Such arguments are often resisted on the grounds that epistemic premises do not entail ontological conclusion. My view is that one can legitimately infer ontological conclusions from epistemic premises, if one is very careful about how one reasons. To do so, the best way is to reason first from epistemic premises to modal conclusions (about necessity and possibility), and from there to ontological conclusions. Here, the crucial issue is the link between the epistemic and modal domains. How can one reason from theses about what is knowable or conceivable to theses about what is necessary or possible? To bridge the epistemic and modal domains, the framework of two-dimensional semantics can play a central role. I have used this framework in earlier work (Chalmers 1996) to mount an argument against materialism. Here, I want to revisit the argument, laying it out in a more explicit and careful form, and responding to a number of objections. In what follows I will concentrate mostly on the conceivability argument. I think that very similar considerations apply to the other arguments mentioned above, however. In the final section of the paper, I show how this analysis might yield a unified treatment of a number of anti-materialist arguments

Consciousness and intentionality are perhaps the two central phenomena in the philosophy of mind. Human beings are conscious beings: there is something it is like to be us. Human beings are intentional beings: we represent what is going on in the world.Correspondingly, our specific mental states, such as perceptions and thoughts, very often have a phenomenal character: there is something it is like to be in them. And these mental states very often have intentional content: they serve to represent the world. On the face of it, consciousness and intentionality are intimately connected. Our most important conscious mental states are intentional states: conscious experiences often inform us about the state of the world. And our most important intentional mental states are conscious states: there is often something it is like to represent the external world. It is natural to think that a satisfactory account of consciousness must respect its intentional structure, and that a satisfactory account of intentionality must respect its phenomenological character.With this in mind, it is surprising that in the last few decades, the philosophical study of consciousness and intentionality has often proceeded in two independent streams. This wasnot always the case. In the work of philosophers from Descartes and Locke to Brentano and Husserl, consciousness and intentionality were typically analyzed in a single package. But in the second half of the twentieth century, the dominant tendency was to concentrate on onetopic or the other, and to offer quite separate analyses of the two. On this approach, the connections between consciousness and intentionality receded into the background.In the last few years, this has begun to change. The interface between consciousness and intentionality has received increasing attention on a number of fronts. This attention has focused on such topics as the representational content of perceptual experience, the higherorder representation of conscious states, and the phenomenology of thinking. Two distinct philosophical groups have begun to emerge. One group focuses on ways in which consciousness might be grounded in intentionality. The other group focuses on ways in which intentionality might be grounded in consciousness

More than a decade ago, philosopher John Searle started a long-running controversy with his paper “Minds, Brains, and Programs” (Searle, 1980a), an attack on the ambitious claims of artificial intelligence (AI). With his now famous _Chinese Room_ argument, Searle claimed to show that despite the best efforts of AI researchers, a computer could never recreate such vital properties of human mentality as intentionality, subjectivity, and understanding. The AI research program is based on the underlying assumption that all important aspects of human cognition may in principle be captured in a computational model. This assumption stems from the belief that beyond a certain level, implementational details are irrelevant to cognition. According to this belief, neurons, and biological wetware in general, have no preferred status as the substrate for a mind. As it happens, the best examples of minds we have at present have arisen from a carbon-based substrate, but this is due to constraints of evolution and possibly historical accidents, rather than to an absolute metaphysical necessity. As a result of this belief, many cognitive scientists have chosen to focus not on the biological substrate of the mind, but instead on the abstract causal structure_ _that the mind embodies (at an appropriate level of abstraction). The view that it is abstract causal structure that is essential to mentality has been an implicit assumption of the AI research program since Turing (1950), but was first articulated explicitly, in various forms, by Putnam (1960), Armstrong (1970) and Lewis (1970), and has become known as _functionalism_. From here, it is a very short step to _computationalism_, the view that computational structure is what is important in capturing the essence of mentality. This step follows from a belief that any abstract causal structure can be captured computationally: a belief made plausible by the Church–Turing Thesis, which articulates the power

Consciousness fits uneasily into our conception of the natural world. On the most common conception of nature, the natural world is the physical world. But on the most common conception of consciousness, it is not easy to see how it could be part of the physical world. So it seems that to find a place for consciousness within the natural order, we must either revise our conception of consciousness, or revise our conception of nature. In twentieth-century philosophy, this dilemma is posed most acutely in C. D. Broad’s The Mind and its Place in Nature (1925). The phenomena of mind, for Broad, are the phenomena of consciousness. The central problem is that of locating mind with respect to the physical world. Broad’s exhaustive discussion of the problem culminates in a taxonomy of seventeen different views of the mental-physical relation.1 On Broad’s taxonomy, a view might see the mental as nonexistent (“delusive”), as reducible, as emergent, or as a basic property of a substance (a “differentiating” attribute). The physical might be seen in one of the same four ways. So a four-by-four matrix of views results. (The seventeenth entry arises from Broad’s division of the substance/substance view according to whether one substance or two is involved.) At the end, three views are left standing: those on which mentality is an emergent characteristic of either a physical substance or a neutral substance, where in the latter case, the physical might be either emergent or delusive

There has been much interest in the possibility of connectionist models whose representations can be endowed with compositional structure, and a variety of such models have been proposed. These models typically use distributed representations that arise from the functional composition of constituent parts. Functional composition and decomposition alone, however, yield only an implementation of classical symbolic theories. This paper explores the possibility of moving beyond implementation by exploiting holistic structure-sensitive operations on distributed representations. An experiment is performed using Pollack’s Recursive Auto-Associative Memory. RAAM is used to construct distributed representations of syntactically structured sentences. A feed-forward network is then trained to operate directly on these representations, modeling syn- tactic transformations of the represented sentences. Successful training and generalization is obtained, demonstrating that the implicit structure present in these representations can be used for a kind of structure-sensitive processing unique to the connectionist domain.

In this paper I use thought-experiments to argue that functional organization fully determines conscious experience. These thought-experiments involve the gradual replacement of neurons by silicon chips, and similar scenarios. I argue that if "absent qualia" or "inverted qualia", are possible, then phenomena I call "fading qualia" and "dancing qualia" will be possible; but I argue that it is very implausible that fading or dancing qualia are possible. The resulting position is a sort of nonreductive functionalism

At any given time, a subject has a multiplicity of conscious experiences. A subject might simultaneously have visual experiences of a red book and a green tree, auditory experiences of birds singing, bodily sensations of a faint hunger and a sharp pain in the shoulder, the emotional experience of a certain melancholy, while having a stream of conscious thoughts about the nature of reality. These experiences are distinct from each other: a subject could experience the red book without the singing birds, and could experience the singing birds without the red book. But at the same time, the experiences seem to be tied together in a deep way. They seem to be unified, by being aspects of a single encompassing state of consciousness

This chapter describes three relatively specific forms such as destructive uploading, gradual uploading, and nondestructive uploading. Neuroscience is gradually discovering various neural correlates of consciousness, but this research program largely takes the existence of consciousness for granted. It presents an argument for the pessimistic view and an argument for the optimistic view, both of which run parallel to related arguments that can be given concerning teletransportation. Cryonic technology offers the possibility of preserving our brains in a low‐temperature state shortly after death, until such time as the technology is available to reactivate the brain or perhaps to upload the information in it. Reconstructive uploading from brain scans is closely akin to ordinary (nongradual) uploading from brain scans, with the main difference being the time delay, and perhaps the continued existence in the meantime of the original person.

Does the capacity to think require the capacity to sense? A lively debate on this topic runs throughout the history of philosophy and now animates discussions of artificial intelligence. Many have argued that AI systems such as large language models cannot think and understand if they lack sensory grounding. I argue that thought does not require sensory grounding: there can be pure thinkers who can think without any sensory capacities. As a result, the absence of sensory grounding does not entail that large language models cannot think or understand. I also consider to what extent quasi-sensory grounding can at least boost the performance of a language model.

In this chapter, the author says that the standard view of brain‐in‐a‐vat scenario is endorsed by the people who created The Matrix. The author argues that the hypothesis that he is envatted is not a skeptical hypothesis, but a metaphysical hypothesis. That is, it is a hypothesis about the underlying nature of reality. According to the author, the Matrix Hypothesis is equivalent to a version of the following three‐part Metaphysical Hypothesis. First, physical processes are fundamentally computational. Second, our cognitive systems are separate from physical processes, but interact with these processes. Third, physical reality was created by beings outside physical space‐time. The Metaphysical Hypothesis combines the Creation Hypothesis, the Computational Hypothesis, and the Mind‐Body Hypothesis. It also adds a more specific claim: the computational processes underlying physical space‐time were designed by the creators as a computer simulation of a world.