Liberal Naturalism Having rejected physicalism as a viable ontological framework in which to house p-consciousness, Rosenberg now begins the task of exploring possible alternatives. He will not investigate substance dualism; rather, he will seek to develop a version of Liberal Naturalism, which holds that nature is composed of only one kind of ontological 'stuff,' and that not all aspects of this stuff are physical. As an opening remark, Rosenberg notes that, insofar as physicalist views introduce "anomolous standards of explanation" for p-consciousness (see chapter 3) in order to avoid rejecting the prevailing metaphysical paradigm, such views are ontologically conservative at the expense of being methodologically radical. In contrast, a Liberal Naturalist bears no strong prior commitments to a given metaphysic, and believes that our highest priority as theory makers should be to achieve a natural and rigorous account of p-consciousness and its place in nature. Thus, a Liberal Naturalist is methodologically conservative at the expense of being ontologically radical. As Rosenberg puts it, "One might suggest that Liberal Naturalism is metaphysics in the service of explanation, whereas physicalism is explanation in service to metaphysics" (pg. 78). Rosenberg's Liberal Naturalist framework will be a variant of views that have been put forth before, notably by Alfred North Whitehead and Bertrand Russell, and more recently endorsed by philosophers such as David Chalmers, Michael Lockwood, Galen Strawson, and Thomas Nagel. Nagel's depiction of this view as quoted in the text is eloquent enough to bear repeating in full: Although the view that physical phenomena have contents or inner aspects related to experience appears promising, Rosenberg argues that those who have endorsed it in the past have not gone far enough. They have treated the view more as an amendment to physicalism rather than a thorough revision, and as Rosenberg works to flesh out his Liberal Naturalist view more fully throughout the book, he makes the case that nothing less than a thorough revision of our theories on how nature works (in particular, how causation works) will be sufficient to find a home for subjective experience. To guide his investigation over the next few chapters, Rosenberg will draw out those issues and problems surrounding p-consciousness which pose fundamental challenges and paradoxes to our understanding of experience and its relationship to the greater world. In so doing, he aims to discover more precisely the ways in which our current understanding of the world is inadequate, which will in turn crucially inform the shape of his particular Liberal Naturalist theory. Properly constructed, the new theory's metaphysical outlook and explanitory power should then be able to address these paradoxes directly and dissolve them into tractable problems with satisfactory solutions. Rosenberg will meet this challenge in the second half of the book. Because Rosenberg is in search of a new fundamental understanding of nature, the sort of problems he will consider here will not be ones that challenge our high level notions of mind, or other cognitive phenomena of the sort that might be studied by cognitive science or neuroscience. (Such problems are important and will be addressed eventually in Rosenberg's framework, but will not be suitable for motivating the fundamental shape of his Liberal Naturalist theory.) Rather, the problems considered will be of a more fundamental sort, problems that strike at the very heart of how we view nature in general. The first such problem that Rosenberg considers is the boundary problem. The Boundary Problem We begin discussion of the boundary problem with some observations that Rosenberg takes to be uncontentious. These are: 1) Experiencing subjects (such as you and I) come in discrete units. Each 'unit' of experience contains a dynamic field of phenomenal events that are somehow naturally unified to constitute the subject. 2) The phenomenal field of an experiencing subject has boundaries. For instance, a boundary belongs to both your and my phenomenal fields, such that you do not experience my pains and I do not experience yours. 2.5) Together, the boundedness and unity of the phenomenal field make for a sort of inherent, natural individuation for experiencing subjects. Without these twin aspects of boundedness and unity, nothing like a human experiencing subject could exist. (Rosenberg states this immediately following his second observation, but I think it's important enough in the context of the discussion to come to merit its own listing here.) 3) Human consciousness is only a particular instance of the more general concept of an experiencing subject. Other kinds of subjects with experiences vastly different from humans might exist. 4) Human consciousness is tied to the physical body and its cognitive processes, which exist at a middle level in nature. Individuation at this middle level tends to be highly context sensitive and interest relative in a way that individuation of the world's fundamental microphysical constituents, and the universe as a whole, are not. 5) Various levels of cohesion and organization exist between microphysical phenomena and middle level human cognitive processes, and likewise between human cognition and the universe as a whole. The task before us is to pull these observations together to account for the boundedness of subjective experience and how it could exist in nature. Why is it that experience is bounded at all, and what aspects of nature support the fact that human p-consciousness is individuated at the middle level in the particular way that it is? If humans' phenomenal fields are tied to their physical bodies, and human p-conscious is individuated at a middle level of nature, then how are the relevant parts of the physical human body likewise individuated at the middle level? These questions form the boundary problem for experiencing subjects. Because we have no good answer to the boundary problem, our conception of where the boundaries that individuate experiening subjects find their expression in nature is extremely loose. We can draw a virtually arbitrary amount of imaginary boundaries in nature that might support experiencing subjects without fear of contradicting what we otherwise know about the world, and the results of our thought experiments can be surprising, absurd, or even (for the human case) outright false. For instance, Rosenberg cites various neuroscientific research that seems to indicate that global, synchronous neuronal activity in the cortex plays a role in establishing the boundedness and unity of a human's phenomenal experience. If this is right, might it not be the case that some subsets of this synchronous cortical activity themselves present sufficient conditions to support the existence of experiencing subjects (albeit ones less cognitively complex than, and perhaps of a phenomenal character alien to, the 'full blown' human consciousness with which we are acquainted)? Maybe, maybe not-- we don't appear to have the relevant concepts needed to decide the issue. Although such a situation might appear surprising if it were true, it seems as if we at least have to grant the possibility, given what knowledge and theory we have to work with. (Interestingly, Rosenberg suggests that we may already have empirical evidence from multiple personal disorder studies that a single human brain can support multiple experiencing subjects on the same upper level of cortical organization.) Rosenberg uses thought experiments in order to show the extent to which our loose concepts pertaining to the boundary problem can be stretched without breaking. For a given cognitive system, it seems coherent to suppose that various subsystems within it are experiencing subjects, but that the system as a whole is not. Likewise, it seems coherent to suppose that both the subsystems and the system as a whole are individual experiencing subjects. There is no ceiling that tells us at what point we should stop attributing subjecthood to larger portions of the system. Extending beyond biological systems, we cannot even rule out the idea that an entire economy might provide the proper kind of causal organization to support the existence of an experiencing subject, even if this strikes us as strange or outright absurd. If there is no immediate ceiling constraining how high we can potententially attribute experiential subjecthood, there is no immediate floor either. For a cognitive system, we can just as well suppose that the parts are not subjects of experience but that the whole is, e.g. because some (nebulously conceived but often alluded to) point of sufficient complexity has been achieved by the whole but not the parts. But if this were the case, what is to stop us from conceiving of a world where the point of sufficient complexity for experiential subjecthood has been modified? In conjunction with our previous conjectures, we might conceive of a world where the point of sufficient complexity is elevated above the level of complexity exhibited by human brains but below that of the economy. In such a world, humans would not be experiencing subjects, but the economy would. Rosenberg argues that we can shift the conceptual boundaries across nature so freely because of the way we characterize phenomena at its middle level. We carve up the world at this middle level according to some interest relative, abstract patterns that are extracted from the actual, underlying microphysical phenomena, and there are arbitrarily many of such patterns that are consistent with the same physical/causal circumstances. As a consequence, we wind up with arbitrarily many abstract patterns of organization that present themselves as candidates to support the individuation of experiencing subjects, with sometimes counterintuitive and even bewildering results. It is clear that such interest relative descriptions of the middle level of nature will not do. As Rosenberg says, "We need a natural criterion for individuation, one that illuminates the specialness of some patterns over others as supporters of experience" (pg. 87)-- we need boundaries and unities that are in some sense actually, objectively existent and recognized by nature, not ones created by observors and projected onto nature. The fundamental microphysical entities of the world, be they particles or strings or something else, appear to be good candidates to play the role of these naturally bounded, actually existent units. But this leaves us with a bootstrapping problem. If microphysical entities provide the boundaries for experiencing subjects, how is it that humans at the middle level of nature, towering far above the level of these microphysical individuals, could be experiencing subjects as well? Another good suggestion is that natural boundaries flow along the lines of causal interaction in the world, but this leaves us with the problem of halting a runaway process. In this case, it appears as if we cannot ultimately individuate any given phenomena in the visible universe from one another, and we are left with only the universe as a whole as an experiencing subject. Once again, we have not accomodated experiencing subjects at a middle level of nature. We are not without hope, however. The suggestion that causation grounds natural individuation remains a promising possibility, since if anything meets the criterion of being an inherent organizational feature of nature, it would seem to be causal interaction. But how do we prevent causal interaction from individuating anything smaller than the entire universe? Rosenberg takes Michael Lockwood's words to be suggestive: "quantum mechanics seems to be telling us that it is a classical prejudice to suppose that the world is not intrinsically structured at anything but the level of elementary particles, and their actions and interactions.2" Perhaps a closer analysis of causation in the spirit of Lockwood's observation could suggest ways in which causation actually might provide a basis for natural individuation at the middle level of nature. If so, we would seem to have the makings of a satisfactory response to the boundary problem. 1. Nagel, Thomas. (1998) "Conceiving the Impossible and the Mind-Body Problem." Philosophy 73, no. 285:337-52. 2. Lockwood, Michael. (1993) "The Grain Problem." In Objections to Physicalism, edited by Howard Robinson, 271-91. Oxford: Clarendon Press.