Online research in philosophy

We show that cast shadows can have a significant influence on the speed of visual search. In particular, we find that search based on the shape of a region is affected when the region is darker than the background and corresponds to a shadow formed by lighting from above. Results support the proposal that an early-level system rapidly identifies regions as shadows and then discounts them, making their shapes more difficult to access. Several constraints used by this system are mapped out, including constraints on the luminance and texture of the shadow region, and on the nature of the item casting the shadow. Among other things, this system is found to distinguish between line elements (items containing only edges) and surface elements (items containing visible surfaces), with only the latter deemed capable of casting a shadow.

This paper sets forth a new theory of quantifiers and term connectives, called shadow theory , which should help simplify various semantic theories of natural language by greatly reducing the need of Montagovian proper names, type-shifting, and λ-conversion. According to shadow theory, conjunctive, disjunctive, and negative noun phrases such as John and Mary , John or Mary , and not both John and Mary , as well as determiner phrases such as every man , some woman , and the boys , are all of semantic type e and denote individual-like objects, called shadows — conjunctive , disjunctive , or negative shadows, such as John-and-Mary, John-or-Mary, and not-(John-and-Mary). There is no essential difference between quantification and denotation: quantification is nothing but denotation of shadows. Individuals and shadows constitute a Boolean structure. Formal language LSD (Language for Shadows with Distributivity), which takes compound terms to denote shadows, is investigated. Expansions and enrichments of LSD are also considered toward the end of the paper.

Roy Sorensen’s adventure in Shadowland started with his prize-winning article, "Seeing Intersecting Eclipses" (published in The Journal of Philosophy, and chosen by the board of the Philosopher’s Annual as one of the ten best philosophy articles of 1999), which is the basis for the first two chapters in this book. The recipe adopted in that article is followed in most of the following thirteen chapters, five of them being based on Sorensen’s previous articles on the topic: start with an open mind regarding the existence and causal efficacy of absences, shadows, i.e. absences of light, in our case, devise a riddle involving perception of such absences, and draw the consequences for the philosophy of perception and/or ontology.

Berkeley thinks that we only see the size, shape, location, and orientation of objects in virtue of the correlation between sight and touch. Shadows have all of these spatial properties and yet are intangible. In Seeing Dark Things (2008), Roy Sorensen argues that shadows provide a counterexample to Berkeley's theory of vision and, consequently, to his idealism. This paper shows that Berkeley can accept both that shadows are intangible and that they have spatial properties.

The old puzzle of material constitution has benefited from a lot of thorough discussion from the part of metaphysicians in the last thirty-odd years. The available solution options and their problems are by now familiar. They involve particular views on mainstream entities and relations of metaphysical inquiry, like objects, properties, events, causation, identity, supervenience, and so on. However, one might want to hope, together with some contemporary ontologists, most notably Roberto Casati and Achille Varzi (1994), that dealing with more peripheral entities is not without interest even when it comes to solving mainstream questions of metaphysics. This I am going to do here, with the puzzle of material constitution in the role of the mainstream ontological issue and shadows in the role of the minor, superficial, or peripheral entity.

Sorensen’s celebrated problem about the eclipse of Near and Far is given a solution in which what is seen is Far, silhouetted. Near cannot be seen, as it is in the shadow of Far. A silhouette is a shadow. The so–called Yale Puzzle is a linguistic confusion.

The eclipse riddle -- Seeing surfaces -- The disappearing act -- Spinning shadows -- Berkeley's shadow -- Para-reflections -- Para-refractions : shadowgrams and the black drop -- Goethe's colored shadows -- Filtows -- Holes in the light -- Black and blue -- Seeing in black and white -- We see in the dark -- Hearing silence.

In his latest book, Roy Sorensen offers a solution to a puzzle he put forward in an earlier article -The Disappearing Act. The puzzle involves various question about how the causal theory perception is to be applied to the case of seeing shadows. Sorensen argues that the puzzle should be taken as bringing out a new way of seeing shadows. I point out a problem for Sorensen’s solution, and offer and defend an alternative view, according to which the puzzle is to be interpreted as showing a new way of seeing objects, in virtue of their contrast with light.

Mainstream metaphysics has been preoccupied by inquiring into the nature of major kinds of entities, like objects, properties and events, while avoiding minor entities, like shadows or holes. However, one might want to hope that dealing with such minor entities could be profitable for even solving puzzles about major entities. I propose a new ontological puzzle, the Shadow of Constitution Puzzle, incorporating the old puzzle of material constitution, with shadows in the role of the minor entity to guide our approach to the issues involved. I then analyze the standard answers to the original puzzle of constitution, in their role as potential solutions to the new puzzle. Finally, I discuss three views that can solve the proposed puzzle.

The Yale shadow puzzle1 purports to involve the ultimate incompatibility of the following plausible looking principles: (1) If X casts any shadow, then some light is falling directly on X. (2) Shadows cannot be cast through an opaque object. (3) Every shadow is the shadow of something. Imagine a high wall casting a shadow on the ground on a sunny day, and a little bird standing on the ground within the shadow cast by the wall. Is the shadow that is present on the ground under the bird –let’s mark it with S- the shadow of the bird, or (part of) the shadow of the wall? It cannot be the bird’s, by proposition (1), as the bird does not block any light. Neither can it be the wall’s, by proposition (2), as the wall cannot cast its shadow through the opaque bird. Yet, by proposition (3), it has to be the shadow of something. Roy Sorensen has offered neat looking solution to the puzzle; however, part of my goal in this paper is to show that this solutions doesn’t work for a new version of the Yale shadow puzzle, which I call “The Bilkent shadow puzzle”, in acknowledgment of my own academic affiliation. The remaining issue will be to offer a new solution that would cover both puzzles. As it will turn out, the solution is based on a peculiar understanding of the ontology of shadows.