Online research in philosophy

The connectionist vehicle theory of phenomenal experience in the target article identifies consciousness with the brain’s explicit representation of information in the form of stable patterns of neural activity. Commentators raise concerns about both the conceptual and empirical adequacy of this proposal. On the former front they worry about our reliance on vehicles, on representation, on stable patterns of activity, and on our identity claim. On the latter front their concerns range from the general plausibility of a vehicle theory to our specific attempts to deal with the dissociation studies. We address these concerns, and then finish by considering whether the vehicle theory we have defended has a coherent story to tell about the active, unified subject to whom conscious experiences belong.

When cognitive scientists apply computational theory to the problem of phenomenal consciousness, as many of them have been doing recently, there are two fundamentally distinct approaches available. Either consciousness is to be explained in terms of the nature of the representational vehicles the brain deploys; or it is to be explained in terms of the computational processes defined over these vehicles. We call versions of these two approaches vehicle and process theories of consciousness, respectively. However, while there may be space for vehicle theories of consciousness in cognitive science, they are relatively rare. This is because of the influence exerted, on the one hand, by a large body of research which purports to show that the explicit representation of information in the brain and conscious experience are dissociable, and on the other, by the classical computational theory of mind – the theory that takes human cognition to be a species of symbol manipulation. But two recent developments in cognitive science combine to suggest that a reappraisal of this situation is in order. First, a number of theorists have recently been highly critical of the experimental methodologies employed in the dissociation studies – so critical, in fact, it’s no longer reasonable to assume that the dissociability of conscious experience and explicit representation has been adequately demonstrated. Second, classicism, as a theory of human cognition, is no longer as dominant in cognitive science as it once was. It now has a lively competitor in the form of connectionism; and connectionism, unlike classicism, does have the computational resources to support a robust vehicle theory of consciousness. In this paper we develop and defend this connectionist vehicle theory of consciousness. It takes the form of the following simple empirical hypothesis: phenomenal experience consists in the explicit representation of information in neurally realized PDP networks. This hypothesis leads us to re-assess some common wisdom about consciousness, but, we will argue, in fruitful and ultimately plausible ways.

In this paper, we present an account of phenomenal consciousness. Phenomenal consciousness is experience, and the problem of phenomenal consciousness is to explain how physical processes?behavioral, neural, computational?can produce experience. Numerous thinkers have argued that phenomenal consciousness cannot be explained in functional, neural or information-processing terms (e.g. Block 1990, 1994; Chalmers 1996). Different arguments have been put forward. For example, it has been argued that two individuals could be exactly alike in functional/computational/behavioral measures, but differ in the character of their experience. Though such persons would behave in the same way, they would differ in how things felt to them (for example, red things might give rise to the experience in one that green things give rise to in the other). Similarly, it has been held that two individuals could be functionally/computationally/behaviorally alike although one of them, but not the other, is a mere zombie, that is, a robot-like creature who acts as if it has experience but is in fact phenomenally unconsciousness. For any being, it has been suggested, the question whether it has experience (is phenomenally conscious) cannot be answered by determining that it is an information-processor of this or that sort. The question is properly equivalent to the question whether there is anything it is like to be that individual (Nagel 1974). Attempts to explain consciousness in physical or information-processing terms sputter: we cannot get any explanatory purchase on experience when we try to explain it in terms of neural or computational processes. Once a particular process has been proposed as an explanation, we can then always reasonably wonder, it seems, what it is about that particular process that make it give rise to experience. Physical and computational mechanisms, it seems, require some further ingredient if they are to explain experience. This explanatory shortfall has aptly been referred to as "the explanatory gap" (Levine 1983)..

O'Brien & Opie run into conceptual problems trying to equate stable patterns of neural activation with phenomenal experiences. They also seem to make a logical mistake in thinking that the brute association between stable neural patterns and phenomenal experiences implies that they are identical. In general, the authors do not provide us with a story as to why stable neural patterns constitute phenomenal experience.

from non-conscious components by positing that consciousness is a universal primitive. For example, the double aspect theory of information holds that infor- mation has a phenomenal aspect. How then do you get from phenomenal infor- mation to human consciousness? This paper proposes that an entity is conscious to the extent it amplifies information, first by trapping and integrating it through closure, and second by maintaining dynamics at the edge of chaos through simul- taneous processes of divergence and convergence. The origin of life through autocatalytic closure, and the origin of an interconnected worldview through conceptual closure, induced phase transitions in the degree to which informa- tion, and thus consciousness, is locally amplified. Divergence and convergence of cognitive information may involve phenomena observed in light e.g. focusing, interference, and resonance. By making information flow inward- biased, clo- sure shields us from external consciousness; thus the paucity of consciousness may be an illusion.

Though we fully agree that unconscious processing produces explicit representations that form the conscious phenomenal experience of the subject, identifying phenomenal experience with stable patterns of activation in a PDP network seriously limits O'Brien & Opie's thesis. They fail to recognize the constructive role of consciousness during the learning episode itself, reducing consciousness to a resulting outcome of the learning episode. We illustrate how consciousness can guide and shape the formation of increasingly structured representations of the world by presenting a brief outline of a model for speech segmentation.

Electronic Mail: jimenez@usc.es Abstract Stability of activation, while it may be necessary for information to become available to consciousness, is not sufficient to produce phenomenal experience. We suggest that consciousness involves access to information and that access makes information symbolic. From this perspective, implicit representations exist, and are best thought of as sub-symbolic. Crucially, such representations can be causally efficacious in the absence of consciousness.

Many of the arguments about how to address the hard versus the easy questions of consciousness put by Chalmers (1995) are similar to ones I have developed in Velmans (1991a,b; 1993a). This includes the multiplicity of mind/body problems, the limits of functional explanation, the need for a nonreductionist approach, and the notion that consciousness may be related to neural/physical representation via a dual-aspect theory of information. But there are also differences. Unlike Chalmers I argue for the use of neutral information processing language for functional accounts rather than the term "awareness." I do not agree that functional equivalence cannot be extricated from phenomenal equivalence, and suggest a hypothetical experiment for doing so - using a cortical implant for blindsight. I argue that not all information has phenomenal accompaniments, and introduce a different form of dual-aspect theory involving "psychological complementarity." I also suggest that the hard problem posed by "qualia" has its origin in a misdescription of everyday experience implicit in dualism.

As far as an adequate understanding of phenomenal consciousness is concerned, representationalist theories of mind which are modelled on the information processing paradigm, are, as much as corresponding neurobiological or functionalist theories, confronted with a series of arguments based on inverted or absent qualia considerations. These considerations display the following pattern: assuming we had complete knowledge about the neural and functional states which subserve the occurrence of phenomenal consciousness, would it not still be conceivable that these neural states (or states with the same causal r.