Roberto Casati

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.

Holes are a good example of the sort of entity that down-to-earth philosophers would be inclined to expel from their ontological inventory. In this work we argue instead in favor of their existence and explore the consequences of this liberality—odd as they might appear. We examine the ontology of holes, their geometry, their part-whole relations, their identity and their causal role, the ways we perceive them. We distinguish three basic kinds of holes: blind hollows, perforating tunnels, and internal cavities, treating these uniformly as immaterial bodies. We develop a morphology of holes, focusing on the way a hole can be filled, and then look at the main properties of the resulting conceptual framework: holes are parasitic upon the surfaces of their hosts; holes can move, fuse into each other, split; they can be born, develop, and die. Finally, we examine how some morphological features of holes are represented in perception, including the conditions whereby we have the impression that we see, feel, or even hear a hole. The book has over 150 pictures and is completed by a formal appendix, a section with puzzles and exercises, and a extensive annotated bibliography.

Alexandre Koyré wrote that Newton and the science that followed led to a splitting of the world: on the one hand is the “world of qualities and of sensible perceptions”, on the other is the “world of quantities and of reified geometry”. A comparison between facts held true by common sense and false by the scientific image of the world (or vice versa) seems to confirm this view. But is the dichotomy a real one? Is the world of common sense really “another world” relative to the world of the natural sciences? In this paper we argue in support of a negative answer.

Some concepts, such as colour concepts or value concepts, seem to bear traces of the mind's own make-up. For instance, an extreme position would be that colours and values are not in the world at all, they instead are mere projections that tell us more about the users of response-dependent concepts than about the world they inhabit. But even setting aside such extreme views, a number of important philosophical and psychological questions remain open. What exactly is response-dependence, and does any concept have this feature? What is the appropriate metaphysics for properties represented by response-dependent concepts, and for these concepts themselves? What determines the extension of such properties? How are we to account for knowledge expressed in terms of response-dependent concepts? What mechanisms correctly explain the origins of response-dependent concepts, and their role in representation?

Some concepts, such as colour concepts or value concepts, seem to bear traces of the mind's own make-up. For instance, the character of perceptually-determined colour concepts seems in some sense derivative from the character of the visual system. Thus, it has seemed plausible to claim that the corresponding colour properties are dispositions to elicit certain visual experiences in normal observers under suitable conditions. Much the same has been suggested for value concepts. An extreme position would be that colours and values therefore are not in the world at all, they instead are mere projections that tell us more about the users of response-dependent concepts than about the world they inhabit. But even setting aside such extreme views, a number of important philosophical and psychological questions remain open. What exactly is response-dependence, and does any concept have this feature? What is the appropriate metaphysics for properties represented by response-dependent concepts, and for these concepts themselves? What determines the extension of such properties? How are we to account for knowledge expressed in terms of response-dependent concepts? What mechanisms correctly explain the origins of response-dependent concepts, and their role in representation? This volume brings together a wide range of views on these questions.

We discuss the distinction between the sensory modalities; the metaphysics of sounds; and the structure of sound space. We defend a physicalist conception of sounds, without accepting the identification of sounds with sound-waves in the medium. Sounds, we hold, are events in resonating objects. We evaluate the two main accounts of orientation in perceptual space: relationism and absolutism. We then address Strawson's problem of whether the logical space of sounds could be spatial in the full sense of the term. In the Appendix, we discuss the logic of perceptual auditory reports, and show their compatibility with our theory of sounds.

Surprise has been characterized has an emotional reaction to an upset belief having a heuristic role and playing a criterial role for belief ascription. The discussion of cases of diachronic and synchronic violations of coherence suggests that surprise plays an epistemic role and provides subjects with some sort of phenomenological access to their subpersonal doxastic states. Lack of surprise seems not to have the same epistemic power. A distinction between belief and expectation is introduced in order to account for some aspects of surprise: expectations are construed as volatile representations that tie belief to action. In the cases in which action is not involved, general, “ideological,” expectations are generate in strict connection with the context and with the possibilities of action.

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.