Roberto Casati

The so-called "virtual world" is often described with the help of metaphors derived from ordinary discourse on perception and action. This should not be surprising, since virtual objects were partly conceived on the basis of these metaphors. Yet, it is not a given that these metaphors are appropriate; one might need to begin using different concepts and eventually to invent new ones, more appropriate to the phenomena they describe. It might even happen, as I shall show, that these new concepts will themselves be used in situations described by the discourses on perception, action and social behaviour in a way that so far seems perfectly natural, but that, in turn, might reveal itself to be entirely inadequate. One could use these new metaphors, born as they are of new practices and new usages, for the reinterpretation of the non virtual world. The subject of this piece is the metaphysics of the book. I shall look at the way in which the Web frees it from our inadequate conception of it. This emancipation, strangely, seems to involve an economic liberation.

This issue of The Monist is devoted to the metaphysics of lesser kinds, which is to say those kinds of entity that are not generally recognized as occupying a prominent position in the categorial structure of the world. Why bother? We offer two sorts of reason. The first is methodological. In mathematics, it is common practice to study certain functions (for instance) by considering limit cases: What if x = 0? What if x is larger than any assigned value? Physics, too, often studies the (idealized) initial and boundary conditions of a given system: What would happen in the case of a perfect sphere, or a perfectly black body? In the cognitive sciences, research often thrives on the analysis of cognitive errors, perceptual illusions, brain pathologies. Also in logic one can learn a lot by studying special, anomalous scenarios such as those exhibited by the paradoxes: it is unlikely that we actually find ourselves in a soritical context, or in a liar-like situation, but the fact that we might—or simply the fact that we can conceive of such a possibility—is important enough to deserve careful consideration. In short, the odd, the unfamiliar, the extra-ordinary, the limit cases are perfectly at home in scientific and more broadly intellectual discourse at various levels, where they can be fruitfully engaged in a sophisticated way (witness the existence of specific confining and managing strategies for dealing with them); and they are important precisely because they instruct us concerning the normal, the obvious, and the paradigmatic. The same goes for metaphysics, we submit. Although its major concern is, naturally, with such core entities as substances, properties, or hunks of solid matter, a lot may be learned by paying attention to those limit cases where we find ourselves dealing with entities of much lesser kinds, whether real or putative.

What are the relationships between an entity and the space at which it is located? And between a region of space and the events that take place there? What is the metaphysical structure of localization? What its modal status? This paper addresses some of these questions in an attempt to work out at least the main coordinates of the logical structure of localization. Our task is mostly taxonomic. But we also highlight some of the underlying structural features and we single out the interactions between the notion of localization and nearby notions, such as the notions of part and whole, or of necessity and possibility. A theory of localization—we argue—is needed in order to account for the basic relations between objects and space, and runs afoul a pure part-whole theory. We also provide an axiomatization of the relation of localization and examine cases of localization involving entities different from material objects.

Ordinary reasoning about space—we argue—is first and foremost reasoning about things or events located in space. Accordingly, any theory concerned with the construction of a general model of our spatial competence must be grounded on a general account of the sort of entities that may enter into the scope of the theory. Moreover, on the methodological side the emphasis on spatial entities (as opposed to purely geometrical items such as points or regions) calls for a reexamination of the conceptual categories required for this task. Building on material presented in an earlier paper, in this work we offer some examples of what this amounts to, of the difficulties involved, and of the main directions along which spatial theories should be developed so as to combine formal sophistication with some affinity with common sense.

Understanding of elementary topological equivalencies is impaired by preconceptions about the topological structure of ordinary objects, so that the equivalencies turn out to be counterintuitive. Here I will discuss some of these preconceptions, namely the dominance of gestalt properties of the visual display of the configuration, the neglect of holistic properties, the dominance of transformations the preserve metric properties over those that preserve topological properties only, the assumption that holes are objects of their own. These factors delineate an empirical research field, intuitive topology. An explanatory hypothesis for the preconceptions suggests that they are hard-wired.

This major bibliography offers a comprehensive overview of the recent literature on the nature of events and the place they occupy in our conceptual scheme. The subject has received extensive consideration in the philosophical debate over the last few decades, with ramifications reaching far into the domains of allied disciplines such as linguistics and the cognitive sciences. The starting point for this work is Hans Reichenbach's pioneering contribution on the logical form of action sentences, and the broad scope includes entries from the philosophy of action, the philosophy of mind, the philosophy of space, time, and causation, and situation theory. Approximately 1,850 entries from more than 900 authors are listed in alphabetical/chronological order by author, and most entries are annotated. This excellent work also includes Subject, Name, and Second and Subsequent Authors indexes.

Classically, truth and falsehood are opposite, and so are logical truth and logical falsehood. In this paper we imagine a situation in which the opposition is so pervasive in the language we use as to threaten the very possibility of telling truth from falsehood. The example exploits a suggestion of Ramsey’s to the effect that negation can be expressed simply by writing the negated sentence upside down. The difference between ‘p’ and ‘~~p’ disappears, the principle of double negation becomes trivial, and the truth/falsehood opposition is up for grabs. Our moral is that this indeterminacy undermines the idea of inferential role semantics.

We provide some meta-theoretical constraints for the evaluation of a-spatial theories of sounds and auditory perception. We point out some forms of spatial content auditory experience can have. If auditory experience does not necessarily have a rich egocentric spatial content, it must have some spatial content for the relevant mode of perception to be recognizably auditory. An auditory experience devoid of any spatial content, if the notion makes sense at all, would be very different from the auditory experiences we actually enjoy. This is enough to dismiss current a-spatial theories of auditory perception. As a consequence, our initial taxonomy of proximal, medial, and distal theories, as well as our phenomenological argument in favor of distal theories, are still topical.

In this article I assess some results that purport to show the existence of a type of 'topological perception', i.e., perceptually based classification of topological features. Striking findings about perception in insects appear to imply that (1) configural, global properties can be considered as primitive perceptual features, and (2) topological features in particular are interesting as they are amenable to formal treatment. I discuss four interrelated questions that bear on any interpretation of findings about the perception of topological properties: what exactly are topological properties, what makes them global , in what sense the quoted findings makes them primitive, and what are the hopes of a formal theory of perception based upon them. I suggest that mathematical topology is not the correct model for cognition topological properties, hence that some other formalism ought to be used—a form of “internalized topology.” However, once the principles of this type of topology are spelled out, they may not be as globalistic as one may have expected.