Roy Sorensen

Whereas the positive tourist travels to see what is there, the negative tourist travels to see what is not there. Travel he must, because the absences are only visible at specific sites. Tourist agencies promote the visibility of these spectacles with pointers, telescopes, and helicopter rides. Other parties try to render the absences invisible. For instance, after the theft of the _Mona Lisa_ in 1911, crowds thronged to the Louvre to view its absence. Curators eventually filled the gap by shuffling the order of the ambient paintings. Efforts to erase the absence sometimes yield new ways to perceive the absence. Once the suppresser detects the backfire, he attempts another erasure. Since this may itself backfire (thanks to the machinations of the friends of the absence) an arms race develops. This tug of war helps us to articulate the conditions under which absences are visible—and invisible.

This chapter focuses on armchair inquiry. Thought experiment has the feel of clairvoyance, thus eliciting awe in some and suspicion in others. But the wonder of thought experiment is just a special case of our vague puzzlement about how a question could be answered by merely thinking. There is no mystery when investigators look, measure, and manipulate. Their answers come from the news borne by observation and experiment. But if you just ponder, then the information you have leaving the armchair is the same as the information you had when you sat down. It is argued that part of our wonder is based on a modal fallacy. The theories of armchair inquiry that promise answers to the legitimate portion of our wonder are surveyed. Finally, a cleansing model of rationality that sets the stage for a detailed analysis of how thought experiments work is developed.

This paper is devoted to a solution to Moore's problem. After explaining what Moore's problem is and after considering the main approaches toward solving the problem, I provide a definition of Moorean sentences in terms of pure Moorean propositions. My solution to Moore's problem essentially involves a description of how one can contradict oneself without uttering a contradiction, and a set of definitions that exactly determines which sentences are Moorean and which are close relatives of Moorean sentences.

This is a reply to Casey O'Callaghan and Jonathan Westphal’s comments on Seeing Dark Things: The Philosophy of Shadows. Both attempt to soften the blow to intuition that comes from the most controversial thesis of the book: we see the backs of back-lit objects. Each characterizes the viewing of silhouettes as a kind of marginal seeing that only discloses shapes, sizes and location. In response, photographs are presented to show that silhouettes are typically three-dimensional and they often have internal structure. Consider the silhouette of a bird fluttering inside a cage; we see more than the outline of the cage. Orbiting this main point are subsidiary points about the distinction between shade and shadows, the nature of occlusion, the color black, and peculiarities of absent absences.

Lake Tanganiyka has lefty and righty cichlid fish that show there can be natural selection for a trait over its mirror image counterpart.This raises the question Can there be biological selection of a whole organism over its mirror image counterpart? That is, could the fitness of a fish be altered by simply changing it into its own enantaniomorph? My answer is no. I present Flatlander thought experiment to demonstrate that mirror imagecounterparts are duplicates because they only differ in how they happen to be oriented in space. The counterparts have the same intrinsic properties and are in the same environment,so there can be no difference in fitness.