Can God create a stone too heavy for him to lift? Can time have a beginning? Which came first, the chicken or the egg? Riddles, paradoxes, conundrums--for millennia the human mind has found such knotty logical problems both perplexing and irresistible. Now Roy Sorensen offers the first narrative history of paradoxes, a fascinating and eye-opening account that extends from the ancient Greeks, through the Middle Ages, the Enlightenment, and into the twentieth century. When Augustine asked what God was doing before (...) He made the world, he was told: "Preparing hell for people who ask questions like that." A Brief History of the Paradox takes a close look at "questions like that" and the philosophers who have asked them, beginning with the folk riddles that inspired Anaximander to erect the first metaphysical system and ending with such thinkers as Lewis Carroll, Ludwig Wittgenstein, and W.V. Quine. Organized chronologically, the book is divided into twenty-four chapters, each of which pairs a philosopher with a major paradox, allowing for extended consideration and putting a human face on the strategies that have been taken toward these puzzles. Readers get to follow the minds of Zeno, Socrates, Aquinas, Ockham, Pascal, Kant, Hegel, and many other major philosophers deep inside the tangles of paradox, looking for, and sometimes finding, a way out. Filled with illuminating anecdotes and vividly written, A Brief History of the Paradox will appeal to anyone who finds trying to answer unanswerable questions a paradoxically pleasant endeavor. (shrink)

Mental time travel is the ability to mentally project oneself backward in time to relive past experiences and forward in time to pre-live possible future experiences. Previous work has focused on MTT in its voluntary form. Here, we introduce the notion of involuntary MTT. We examined involuntary versus voluntary and past versus future MTT in a diary study. We found that involuntary future event representations—defined as representations of possible personal future events that come to mind with no preceding search attempts—were (...) as common as involuntary autobiographical memories and similar to them regarding cuing and subjective qualities. Future MTT involved more positive and idyllic representations than past MTT. MTT into the distant future/past involved more representations of cultural life script events than MTT into the immediate past/future. The findings are discussed in relation to cultural learning and MTT considered as a higher mental process. (shrink)

Sorensen provides a panoramic view of paradoxes of theoretical and practical rationality. These puzzles are organized as apparent counterexamples to attractive principles such as the principle of charity, the transitivity of preferences, and the principle that we should maximize expected utility. The following paradoxes are discussed: fearing fictions, the surprise test paradox, Pascal’s Wager, Pollock’s Ever Better wine, Newcomb’s problem, the iterated prisoner’s dilemma, Kavka’s paradoxes of deterrence, backward inductions, the bottle imp, the preface paradox, Moore’s problem, Buridan’s ass, Condorcet’s (...) paradox of cyclical majorities, the St. Petersburg paradox, weakness of will, the Ellsberg paradox, Allais’s paradox, and Peter Cave’s puzzle of self-fulfilling beliefs. (shrink)

In this book, Sorensen presents the first general theory of the thought experiment. He analyses a wide variety of thought experiments, ranging from aesthetics to zoology, and explores what thought experiments are, how they work, and what their positive and negative aspects are. Sorensen also sets his theory within an evolutionary framework and integrates recent advances in experimental psychology and the history of science.

We investigated whether memories are selected for the life story based on event characteristics. Sixty-one students completed weekly diaries over their first term at university. They described, dated and rated two events each week. Three months after the end of the term they completed an unexpected memory test. They recalled three memories from the diary period that were important to their life story. Three randomly selected events scoring low on importance to the life story functioned as control memories. Life story (...) memories were rated higher on goal relevance, emotional intensity, importance and rehearsal in the diary and maintained their higher ratings at the test session, while ratings for control memories dropped off. Life story memories’ content was less consistent over time but they were more accurately dated than control memories. The results suggest that event characteristics play an important role for the selection of life story memories. (shrink)

You face two buttons. Pushing one will destroy Greensboro. Pushing the other will save it. There is no way for you to know which button saves and which destroys. What ought you to do? Answer: You ought to make the correct guess and push the button that saves Greensboro. Second question: Do you have an obligation to push the correct button?

Catholics condemn Immanuel Kant (1724–1804) as a fanatic; he fails to cushion ‘Never lie' with a distinction between venial and mortal sin. But Kant has secular substitutes: lie/mislead, candor/honesty, commission/omission, deception/illusion, discursive/pictorial. Kant weaves these distinctions into a safety net for polite society, business, politics, and religion. Kant's break-away disciple, Johann Gottlieb Fichte (1762–1814) removes this safety net. Any intentional propagation of error suffices for lying. Ditto for refraining to correct a remedial error. Why? Because we all have a duty (...) to perfect each other. This moral development requires rational informed choice. Being misinformed subverts freedom. The medium of misinformation is irrelevant: utterances, silences, pictures, music, dance, private thoughts, telepathy. To Fichte's relief, Kant overcame the temptation to save an innocent man from murder by lying. But Fichte still thought Kant manifested a corrupt mind by merely considering lying! (shrink)

The vanishing point is a representational gap that organizes the visual field. Study of this singularity revolutionized art in the fifteenth century. Further reflection on the vanishing point invites the conjecture that the self is an absence. This paper opens with perceptual peculiarities of the vanishing point and closes with the metaphysics of personal identity.

Can merely thinking about an imaginary situation provide evidence for how the world actually is--or how it ought to be? In this lively book, Roy A. Sorensen addresses this question with an analysis of a wide variety of thought experiments ranging from aesthetics to zoology. Presenting the first general theory of thought experiment, he sets it within an evolutionary framework and integrates recent advances in experimental psychology and the history of science, with special emphasis on Ernst Mach and Thomas Kuhn. (...) Sorensen explores what thought experiments are, how they work, and what their virtues and vices are. In his view, philosophy differs from science in degree, but not in kind. For this reason, he claims, it is possible to understand philosophical thought experiments by concentrating on their resemblance to scientific relatives. Sorensen assesses the hazards of thought experiments and grants that there are interesting ways in which the method leads us astray, but attacks most scepticism about thought experiments as arbitrary. He maintains that they should be used--as they generally are--as part of a diversified portfolio of techniques, creating a network of cross-checks that make for impressive reliability. (shrink)

Involuntary autobiographical memories are conscious memories of personal events that come to mind with no preceding attempts at retrieval. It is often assumed that such memories are closely related to current concerns – i.e., uncompleted personal goals. Here we examined involuntary versus voluntary autobiographical memories in relation to earlier registered current concerns measured by the Personal Concern Inventory . We found no differences between involuntary and voluntary memories with regard to frequency or characteristics of current concern-related contents. However, memories related (...) to current concerns were rated as more central to the person’s identity, life story and expectations for the future than non-concern-related memories, irrespective of mode of recall. Depression and PTSD symptoms correlated positively with the proportion of current concern-related involuntary and voluntary memories. The findings support the view that involuntary and voluntary remembering is subject to similar motivational constraints. (shrink)

Mental time travel is the ability to mentally project oneself into one’s personal past or future, in terms of memories of past events or projections of possible future events. We investigated the frequency and valence of involuntary MTT in the context of high trait worry. High and low worriers recorded the frequency and valence of involuntary memories and future projections using a structured notebook and completed measures probing individual differences related to negative affectivity. Involuntary future projections were as frequent as (...) involuntary memories. We found a positivity bias for both past and future MTT, in that fewer negative events were reported than positive or neutral ones. This positivity bias was greater for future than for past events. Individual differences related to negative affectivity were positively associated with the proportion of negative events, indicating a reduced positivity bias in individuals with a general tendency to experience negative affect. (shrink)

Do not pass by my epitaph, Wayfarer, but when you have stopped, hear and learn, then depart. There is no boat, To carry you to Hades, No ferryman Charon, No judge Aeacus, No Dog Cerberus. All of us below have become bones and ashes. Truly, I have nothing more to tell you. So depart, wayfarer, Lest dead though I am I seem to you to be a teller of vain tales.

Sorensen here offers a unified solution to a large family of philosophical puzzles and paradoxes through a study of "blindspots": consistent propositions that cannot be rationally accepted by certain individuals even though they might by true.

THE PURPOSE OF THIS ARTICLE IS TO SHOW HOW HUME’S SCEPTICISM ABOUT MIRACLES GENERATES "EPISTEMOLOGICAL" SCEPTICISM ABOUT TIME TRAVEL. SO THE PRIMARY QUESTION RAISED HERE IS "CAN ONE KNOW THAT TIME TRAVEL HAS OCCURED?" RATHER THAN "CAN TIME TRAVEL OCCUR?" I ARGUE THAT ATTEMPTS TO SHOW THE EXISTENCE OF TIME TRAVEL WOULD FACE THE SAME METHODOLOGICAL PROBLEMS AS THE ONES CONFRONTING ATTEMPTS TO DEMONSTRATE THE EXISTENCE OF PARANORMAL EVENTS. SINCE HUMEAN SCEPTICISM EXTENDS TO THE STUDY OF PARANORMAL EVENTS (PARAPSYCHOLOGY), HUMEANS (...) ARE COMMITTED TO SCEPTICISM ABOUT THE STUDY OF TIME TRAVEL ("PARAHISTORY"). (shrink)

Seizing the opportunity to apply what they had learned, the students declared a cheating competition. Outspoken participants (future lawyers, politicians, and captains of industry) bragged about their ruses. But to their chagrin, an ethics student prevailed.

If a spinning sphere casts a shadow, does the shadow also spin? This riddle is the point of departure for an investigation into the nature of shadow movement. A general theory of motion will encompass all moving things, not just physical objects. Ultimately, I argue that round shadows do indeed spin. Shadows are followers of the objects that cast them. Parts of the shadow correspond to parts of the leader, so motion of the caster's parts accounts for motions of the (...) shadow's parts. I conclude with a discussion of how the dynamic aspects of shadows impose subtle constraints on other puzzles about shadows. (shrink)

There is no doubt that episodic memory serves communicative functions, but Mahr & Csibra overlook that this is not the only function served by memories of past events. Autobiographical memory research has identified several other functions, including purely directive functions. The functionality of episodic memory is not stable across situations; it varies dynamically with the demands of the retrieval context.

Drawing inspiration from the ethical pluralism of G. E. Moore's Principia Ethica, I contend that one empty world can be morally better than another. By ?empty? I mean that it is devoid of concrete entities (things that have a position in space or time). These worlds have no thickets or thimbles, no thinkers, no thoughts. Infinitely many of these worlds have laws of nature, abstract entities, and perhaps, space and time. These non-concrete differences are enough to make some of them (...) better than others. 1I thank Walter Sinnott-Armstrong, John Carroll, and Gideon Rosen for their comments and suggestions. (shrink)

The vanishing point is a representational gap that organizes the visual field. Study of this singularity revolutionized art in the fifteenth century. Further reflection on the vanishing point invites the conjecture that the self is an absence. This paper opens with perceptual peculiarities of the vanishing point and closes with the metaphysics of personal identity.

Sorensen presents a general theory of thought experiments: what they are, how they work, what are their virtues and vices. On Sorensen's view, philosophy differs from science in degree, but not in kind. For this reason, he claims, it is possible to understand philosophical thought experiments by concentrating on their resemblance to scientific relatives. Lessons learned about scientific experimentation carry over to thought experiment, and vice versa. Sorensen also assesses the hazards and pseudo-hazards of thought experiments. Although he grants that (...) there are interesting ways in which the method leads us astray, he attacks most scepticism about thought experiments as arbitrary. They should be used, he says, as they generally are used--as part of a diversified portfolio of techniques. All of these devices are individually susceptible to abuse, fallacy, and error. Collectively, however, they provide a network of cross-checks that make for impressive reliability. (shrink)

Involuntary autobiographical memories are spontaneously arising memories of personal events, whereas voluntary memories are retrieved strategically. Voluntary remembering has been studied in numerous experiments while involuntary remembering has been largely ignored. It is generally assumed that voluntary recall is the standard way of remembering, whereas involuntary recall is the exception. However, little is known about the actual frequency of these two types of remembering in daily life. Here, 48 Danish undergraduates recorded their involuntary versus voluntary autobiographical memories during a day (...) using a mechanical counter. Involuntary memories were reported three times as frequently as voluntary memories. Compared to voluntary memories, they were associated less with problem solving and social sharing and more with day dreaming, periods of boredom, no reasons for remembering and predominantly came to mind during unfocused attention. The findings suggest that involuntary recall is a typical way of accessing the personal past. (shrink)