Sven Walter

Mental causation, our mind's ability to causally affect the course of the world, is part and parcel of our ‘manifest image’ of the world. That there is mental causation is denied by virtually no one. How there can be such a thing as mental causation, however, is far from obvious. In recent years, discussions about the problem of mental causation have focused on Jaegwon Kim's so-called Causal Exclusion Argument, according to which mental events are ‘screened off’ or ‘preempted’ by physical events unless mental causation is a genuine case of overdetermination or mental properties are straightforwardly reducible to physical properties.

Frank Jackson and Philip Pettit have defended a non-reductive account of causal relevance known as the ‘program explanation account’. Allegedly, irreducible mental properties can be causally relevant in virtue of figuring in non-redundant program explanations which convey information not conveyed by explanations in terms of the physical properties that actually do the ‘causal work’. I argue that none of the possible ways to spell out the intuitively plausible idea of a program explanation serves its purpose, viz., defends non-reductive physicalism against Jaegwon Kim’s Causal Exclusion Argument according to which non-reductive physicalism is committed to epiphenomenalism because irreducible mental properties are ‘screened off’ from causal relevance by their physical realizers. Jackson and Pettit’s most promising explication of a program explanation appeals to the idea of invariance of effect under variation of realization, but I show that invariance of effect under variation of realization is neither necessary nor sufficient for causal relevance.

What is the nature of consciousness? How is consciousness related to brain processes? This volume collects thirteen new papers on these topics: twelve by leading and respected philosophers and one by a leading color-vision scientist. All focus on consciousness in the "phenomenal" sense: on what it's like to have an experience. Consciousness has long been regarded as the biggest stumbling block for physicalism, the view that the mind is physical. The controversy has gained focus over the last few decades, and phenomenal knowledge and phenomenal concepts--knowledge of consciousness and the associated concepts--have come to play increasingly prominent roles in this debate. Consider Frank Jackson's famous case of Mary, the super-scientist who learns all the physical information while confined in a black-and-white room. According to Jackson, if physicalism is true, then Mary's physical knowledge should allow her to deduce what it's like to see in color. Yet it seems intuitively clear that she learns something when she leaves the room. But then how can consciousness be physical? Arguably, whether this sort of reasoning is sound depends on how phenomenal concepts and phenomenal knowledge are construed. For example, some argue that the Mary case reveals something about phenomenal concepts but has no implications for the nature of consciousness itself. Are responses along these lines adequate? Or does the problem arise again at the level of phenomenal concepts? The papers in this volume engage with the latest developments in this debate. The authors' perspectives range widely. For example, Daniel Dennett argues that anti-physicalist arguments such as the knowledge argument are simply confused; David Papineau grants that such arguments at least reveal important features of phenomenal concepts; and David Chalmers defends the anti-physicalist arguments, arguing that the "phenomenal concept strategy" cannot succeed.

In 'Jackson on physical information and qualia' Terry Horgan defended physicalism against Frank Jackson's Knowledge Argument by raising what later has been called the 'mode of presentation reply'- arguingthatthe Knowledge Argumentis fallacious because itsubtly equivocates on two different readings of 'physical information'. In 'Mary, Mary, quite contrary' however, George Graham and Terry Horgan maintain that none of the replies against Jackson has yet been successful, not even Horgan's own 1984 rejoinder.Tosubstantiate their claim, they present an allegedly improved version of the Knowledge Argument, the 'Mary Mary Argument' whose default moral is property-dualism. In section 1, I will set the scene by making some clarifying remarks regarding Jackson's original argument. In section 2, I will consider several objections to the most promising physicalist rejoinder to the Knowledge Argument, the mode of presentation reply. In section 3 I will discuss the Mary Mary Argument and propose the indexical account of consciousness that, as it happens, is based on Horgan's own 1984 account as a possible solution. Finally,in section 4, I will argue that to the extent that the Mary Mary Argument exceeds the force of Jackson's original challenge it coincides with Joe Levine's Explanatory Gap Argument