Church's Thesis asserts that the only numeric functions that can be calculated by effective means are the recursive ones, which are the same, extensionally, as the Turing-computable numeric functions. The Abstract State Machine Theorem states that every classical algorithm is behaviorally equivalent to an abstract state machine. This theorem presupposes three natural postulates about algorithmic computation. Here, we show that augmenting those postulates with an additional requirement regarding basic operations gives a natural axiomatization of computability and a proof of Church's (...) Thesis, as Gödel and others suggested may be possible. In a similar way, but with a different set of basic operations, one can prove Turing's Thesis, characterizing the effective string functions, and--in particular--the effectively-computable functions on string representations of numbers. (shrink)

People usually regard algorithms as more abstract than the programs that implement them. The natural way to formalize this idea is that algorithms are equivalence classes of programs with respect to a suitable equivalence relation. We argue that no such equivalence relation exists.

This festschrift volume is dedicated to Boris (Boaz) Trakhtenbrot on the occasion of his 85th birthday. For over half a century, Trakhtenbrot has been making seminal contributions to virtually all of the central areas of theoretical computer science. He is universally admired as a founding father and long-standing pillar of the discipline of computer science. On Friday, 28 April 2006, the School of Computer Science at Tel Aviv University held a “Computation Day Celebrating Boaz (Boris) Trakhtenbrot's Eighty-Fifth Birthday”. As a (...) follow-up to that event, his students and colleagues were asked to contribute to a volume in his honor and in recognition of his grand contributions to the field. The book opens with two historical overviews and a bibliography. These are followed by 33 thoroughly reviewed technical contributions. The broad range of topics covered include mathematical logic, logics for computer science, mathematics for computer science, automata and formal languages, asynchronous computation, semantics of programming languages, verification, and software engineering. This tapestry of subjects stands as testimony to the vast scope of Trakhtenbrot's achievements and the profound influence he has had on the field. (shrink)

It’s widely accepted that we have most reason to accept theories that best fulfill the following naturalistically respectable criteria: (1) internal consistency, (2) consistency with the facts, and (3) exemplification of the theoretical virtues. It’s also widely accepted that metaphysical theories are necessarily true. I argue that if you accept the aforementioned criteria, you have most reason to reject that metaphysical theories are necessarily true. By applying the criteria to worlds that are all prima facie possible, I show that contingent (...) local matters of particular fact partly determine which theory of composition we should accept at a world. For instance, I argue that when we apply the criteria to our world, we should accept Mereological Nihilism. Furthermore, even if you think that the worlds I mention, such as gunky worlds, are impossible, you should still reject the brute principle that metaphysical theories are necessarily true. Instead, you should only accept that a theory of composition is necessarily true if contingent local matters of particular fact at possible worlds cannot tell in favor of one theory of composition over another. (shrink)

In recent years, researchers have tried to unpack the meaning of the term flexibility and test how different constructs of flexibility are associated with various psychopathologies. For example, it is apparent that high levels of flexibility allow individuals to adaptively cope and avoid psychopathology following traumatic events, but the precise nature of this flexibility is ambiguous. In this study we focus on two central constructs: cognitive flexibility – the ability to recognize and implement possible responses to a situation– and regulatory (...) flexibility – the ability to modulate emotional expression and experience across situations. We aim to explore the connection between cognitive and regulatory flexibility and evaluate their relative effect on PTSD symptoms. Trauma-exposed college students were assessed for cognitive and regulatory flexibility and current and lifetime PTSD symptoms. We predicted and found a relatively weak, yet significant, overlap between participants’ cognitive and regulatory flexibility. Importantly, while both cognitive and regulatory flexibility were associated with lifetime PTSD symptoms, only cognitive flexibility was associated with current PTSD symptoms. The findings illuminate the possible value of differentiating between constructs of flexibility in predicting short and long-term effects of traumatic exposure and may pave the ground for developing personalized intervention methods. (shrink)

It’s widely accepted that we have most reason to accept theories that best fulfill the following naturalistically respectable criteria: internal consistency, consistency with the facts, and exemplification of the theoretical virtues. It’s also widely accepted that metaphysical theories are necessarily true. I argue that if you accept the aforementioned criteria, you have most reason to reject that metaphysical theories are necessarily true. By applying the criteria to worlds that are all prima facie possible, I show that contingent local matters of (...) particular fact partly determine which theory of composition we should accept at a world. For instance, I argue that when we apply the criteria to our world, we should accept Mereological Nihilism. Furthermore, even if you think that the worlds I mention, such as gunky worlds, are impossible, you should still reject the brute principle that metaphysical theories are necessarily true. Instead, you should only accept that a theory of composition is necessarily true if contingent local matters of particular fact at possible worlds cannot tell in favor of one theory of composition over another. (shrink)

From its beginnings religious philosophy confronted the challenge to reconcile Divine or natural determinism with man's moral freedom. In ancient Jewish thought, this gave rise to statistical ideas. In some Rabbinic texts, necessity is seen as inhering in collectives rather than in individuals. This is a statistical conception. Some miracles too were understood as highly improbable events, and remarkable phenomena were distinguished from usual ones. Medieval thinkers amplified and developed these ideas. Providential as well as natural determinism were explained as (...) operating in large numbers of individual acts of free will, an idea later taken up by Kant. (shrink)

This book taps the best American thinkers to answer the essential American question: How do we sustain our experiment in government of, by, and for the people? Authored by an extraordinary and politically diverse roster of public officials, scholars, and educators, these chapters describe our nation's civic education problem, assess its causes, offer an agenda for reform, and explain the high stakes at risk if we fail.

Falls are a leading cause of serious injury and restricted participation among persons with stroke (PwS). Reactive balance control is essential for fall prevention, however, only a few studies have explored the effects of lesion characteristics (location and extent) on balance control in PwS. We aimed to assess the impact of lesion characteristics on reactive and anticipatory balance capacity, gait, and hemiparetic lower limb function, in PwS. Forty-six subacute PwS were exposed to forward, backward, right and left unannounced horizontal surface (...) translations in 6 increasing intensities, while standing. Fall threshold (i.e., perturbation intensity that results in a fall into the harness system) was measured. In addition, the Berg Balance Scale (BBS), 6 Minute Walk Test (6MWT) and Lower Extremity Fugl-Meyer (LEFM) were measured. Lesion effects were analyzed separately for left- and right-hemisphere damaged (LHD, RHD) patients, using voxel-based lesion-symptom mapping (VLSM). Our results show that voxel clusters where damage exerted a significant impact on balance, gait and lower-limb function were found in the corticospinal tract, in its passage in the corona radiata and in the posterior limb of the internal capsule. Additional significant impact was found to lesions affecting the putamen and the external capsule. Balance, gait, and hemiparetic lower limb function showed much overlap of the corresponding ‘significant’ voxel clusters. Test scores of RHD and LHD patients were affected largely by damage to homologous regions, with the LHD group showing a wider distribution of ‘significant’ voxels. The study corroborates and extends previous findings by demonstrating that balance control, gait, and lower limb function are all affected mainly by damage to essentially the same brain structures, namely - the corticospinal tract and adjacent structures in the capsular-putaminal region. (shrink)

The existence of shoulder abduction (SA) and finger extension (FE) movement capacity shortly after stroke onset is an important prognostic factor, indicating favorable functional outcome for the hemiparetic upper limb. Here we asked whether variation in lesion topography affects these two movements in a similar or a distinct way, and whether lesion impact is similar or distinct for left and right hemisphere damage. SA and FE movements were examined in 77 chronic post-stroke patients using relevant items of the Fugl-Meyer test. (...) Lesion effects were analyzed separately for left and right hemispheric damage (LHD, RHD) patient groups using voxel-based lesion-symptom mapping. In the LHD group, SA and FE were affected only by damage to the cortico-spinal tract in its passage through the corona radiata. In contrast, following RHD, these two movements were affected not only by cortico-spinal tract damage but also by damage to white matter association tracts, the putamen and the insular cortex. In both groups, voxel clusters have been found where damage affected SA and also FE, along with voxels where damage affected only one of the two movements. The capacity to execute SA and FE movements following stroke is affected significantly by damage to shared and distinct voxels in the cortico-spinal tract in LHD patients and by damage to shared and distinct voxels in a larger array of cortical and subcortical regions in RHD patients. (shrink)

The impact of stroke on motor functioning is analyzed at different levels. ‘Impairment’ denotes the loss of basic characteristics of voluntary movement. ‘Activity limitation’ denotes the loss of normal capacity for independent execution of daily activities. Recovery from impairment is accomplished by ‘restitution’ and recovery from activity limitation is accomplished by the combined effect of ‘restitution’ and ‘compensation.’ We aimed to unravel the long-term effects of variation in lesion topography on motor impairment of the hemiparetic lower limb (HLL), and gait (...) capacity as a measure of related activity limitation. Gait was assessed by the 3 m walk test (3MWT) in 67 first-event chronic stroke patients, at their homes. Enduring impairment of the HLL was assessed by the Fugl–Meyer Lower Extremity (FMA-LE) test. The impact of variation in lesion topography on HLL impairment and on walking was analyzed separately for left and right hemispheric damage (LHD, RHD) by voxel-based lesion-symptom mapping (VLSM). In the LHD group, HLL impairment tended to be affected by damage to the posterior limb of the internal capsule (PLIC). Walking capacity tended to be affected by a larger array of structures: PLIC and corona radiata, external capsule and caudate nucleus. In the RHD group, both HLL impairment and walking capacity were sensitive to damage in a much larger number of brain voxels. HLL impairment was affected by damage to the corona radiata, superior longitudinal fasciculus and insula. Walking was affected by damage to the same areas, plus the internal and external capsules, putamen, thalamus and parts of the perisylvian cortex. In both groups, voxel clusters have been found where damage affected FMA-LE and also 3MWT, along with voxels where damage affected only one of the measures (mainly 3MWT). In stroke, enduring ‘activity limitation’ is affected by damage to a much larger array of brain structures and voxels within specific structures, compared to enduring ‘impairment.’ Differences between the effects of left and right hemisphere damage are likely to reflect variation in motor-network organization and post-stroke re-organization related to hemispheric dominance. Further studies with larger sample size are required for the validation of these results. (shrink)

The main powerful method for establishing termination of term rewriting systems was discovered by Nachum Dershowitz through the introduction of certain natural well founded orderings (lexicographic path orderings). This leads to natural decision problems which may be of the highest computational complexity of any decidable problems appearing in a natural established computer science context.

In his opening address, Dershowitz only dealt with the issue obliquely, and devoted most of his time to berating the Palestinians, Chomsky, and professors who criticize Israel, and challenged Chomsky to form an alliance with him to work for peace in the area-- a seemingly worthy proposal but totally off topic. Chomsky began by saying that the only thing Dershowitz said that he couldn't take issue with was that the two of them had once been in some summer (...) camp together. Chomsky then proceeded to provide background to the crisis and pointed out that the current Israel -USA policy and any proposal emanating from it would lead to only further disaster. The Palestinians are not prepared to accept a non-contiguous Bantustan "state" which is what is being offered. Instead he clearly stated that it was the Geneva Accord that provided a basis for meaningful future negotiations. Dershowitz, on the other hand, only at the end, when pressed on this matter, said that the new Sharon-Peres party would "offer" the Palestinians a "proposal"--which the Palestinians should not refuse! This was his answer to "where do we go from here." So much for substance by Dershowitz. Debate score? (shrink)

abstract Can torture be morally justified? I shall criticise arguments that have been adduced against torture and demonstrate that torture can be justified more easily than most philosophers dealing with the question are prepared to admit. It can be justified not only in ticking nuclear bomb cases but also in less spectacular ticking bomb cases and even in the so‐called Dirty Harry cases. There is no morally relevant difference between self‐defensive killing of a culpable aggressor and torturing someone who is (...) culpable of a deadly threat that can be averted only by torturing him. Nevertheless, I shall argue that torture should not be institutionalised, for example by torture warrants. (shrink)

Human rights are often taken for granted, but "What is the basis of human rights?" This is no easy answer, De Xiao Weiqi, in his 2004 book of this difficult the problem. He considered the following four main theories: First, the external theory: the root cause of human rights outside the law, such as human rights divine theory; Second, the intrinsic theory: the root cause of human rights within the law - law positivism ; three, rationalist approaches: human rights is (...) based on rational intuition ; Fourth, experience-based approaches: human rights from human experience, especially experience the experience of injustice. He made ​​the first three theories are severely criticized, and to promote a fourth to experience-based approaches. This paper points out that although the experience of Germany and Xiao Weiqi theory have many advantages, but it is evidence of human rights legislation are vague and inconsistent standards of the Department, and its invention on human rights can not provide more solid foundation. In fact, these issues are perceived more or less de Xiao Weiqi, he repeatedly pointed out that the need for external to the human rights legal standards, I think the divine rights theory is to provide a basis for human rights may be one of the world. De Xiao Weiqi theory of divine criticism of human rights have a good reminder, but I think it still can not rule out the Christ-centered Christian contemporary human rights theory. Human rights are often taken for granted but in fact the origin or foundation of human rights is not an easy question. Alan Dershowitz tries to tackle this thorny issue in his 2004 book: Rights from Wrongs: A Secular Theory of the Origins of Rights. He mainly considers four theories: 1) externalism, eg, the divine source of human rights theory; 2) Internalism, eg, legal positivism; 3) Rationalism, eg, the claim that human rights are founded upon rational intuitions; 4) Experiential approach, ie, human rights are derived from our historical experience of serious wrongs or injustice. He severely criticizes the first three theories, and defends the fourth. In this article, I will point out that despite quite a few merits of Dershowitz's theory; his criteria for the validation of human rights are vague or even inconsistent. His general stance of constructivism towards moral and human rights claims, moreover, are unable to provide solid foundations for human rights. In fact Dershowitz is to some extent aware of these problems, and he feels that human rights do need an objective external source, if only it is possible. I think the theistic worldview is indeed able to provide this objective external source. Dershowitz has raised a lot of good questions for the divine source theory but I argue that in the end they cannot exclude the possibility of a contemporary Christocentric theory of human rights. (shrink)

abstract Can torture be morally justified? I shall criticise arguments that have been adduced against torture and demonstrate that torture can be justified more easily than most philosophers dealing with the question are prepared to admit. It can be justified not only in ticking nuclear bomb cases but also in less spectacular ticking bomb cases and even in the so‐called Dirty Harry cases. There is no morally relevant difference between self‐defensive killing of a culpable aggressor and torturing someone who is (...) culpable of a deadly threat that can be averted only by torturing him. Nevertheless, I shall argue that torture should not be institutionalised, for example by torture warrants. (shrink)

In the aftermath of September 11, 2001, policy makers and others have debated the question of whether or not the United States should torture in an effort to prevent terrorist attacks. In a series of controversial essays, the legal theorist Alan Dershowitz argues that, if a democratic society is going to torture, it should at least be done under the cover of law. To that end, he recommends establishing a legal mechanism by which a judge could issue torture warrants—much (...) as they do now for search warrants. In this essay, I examine Dershowitz's proposal in light of Michael Walzer's classic essay on dirty hands. Just as Walzer uses political theater as a lens for viewing the issue of political assassination, I similarly draw upon a dramatic response to Dershowitz's proposal to think through the issue of torture warrants. (shrink)

teach a course at Harvard with philosopher Robert Nozick and lawyer Alan Dershowitz. We take major issues engaged by each of our professions—from abortion to racism to right-to-die—and we try to explore and integrate our various approaches. We raise many questions and reach no solutions.

In recent years two different axiomatic characterizations of the intuitive concept of effective calculability have been proposed, one by Sieg and the other by Dershowitz and Gurevich. Analyzing them from the perspective of Carnapian explication, I argue that these two characterizations explicate the intuitive notion of effective calculability in two different ways. I will trace back these two ways to Turing’s and Kolmogorov’s informal analyses of the intuitive notion of calculability and to their respective outputs: the notion of computorability (...) and the notion of algorithmability. I will then argue that, in order to adequately capture the conceptual differences between these two notions, the classical two-step picture of explication is not enough. I will present a more fine-grained three-step version of Carnapian explication, showing how with its help the difference between these two notions can be better understood and explained. (shrink)

This timely and passionate book is the first to address itself to Harvard Law Professor Alan Dershowitz’s controversial arguments for the limited use of interrogational torture and its legalisation. Argues that the respectability Dershowitz's arguments confer on the view that torture is a legitimate weapon in the war on terror needs urgently to be countered Takes on the advocates of torture on their own utilitarian grounds Timely and passionately written, in an accessible, jargon-free style Forms part of the (...) provocative and timely _Blackwell Public Philosophy_ series. (shrink)

This volume brings together for the first time thirteen recent interviews with the brightest names in contemporary philosophy, including W.V.O. Quine, Richard Rorty, Stanley Cavell, Hilary Putnam and John Rawls. The pieces are culled from the Harvard Review of Philosophy, which has operated at the core of Harvard's Philosophy Department since 1991. Covering wide range of topics from the philosophy of law to logic to metaphysics to literature, the interviews provide a fascinating introduction to some of the most influential thinkers (...) of the day. The book also includes a foreword by Thomas Scanlon. Interviews with Henry Alison, Stanley Cavell, Alan Dershowitz, Cora Diamond, Umberto Eco, Harvey C. Mansfield, Jr., Alexander Nehemas, Hilary Putnam, W.V. Quine, John Rawls, Richard Rorty, Michael Sandel, Cornel West. (shrink)

This timely and passionate book is the first to address itself to Harvard Law Professor Alan Dershowitz’s controversial arguments for the limited use of interrogational torture and its legalisation. Argues that the respectability Dershowitz's arguments confer on the view that torture is a legitimate weapon in the war on terror needs urgently to be countered Takes on the advocates of torture on their own utilitarian grounds Timely and passionately written, in an accessible, jargon-free style Forms part of the (...) provocative and timely _Blackwell Public Philosophy_ series. (shrink)

This chapter contains section titled: Dershowitz's Argument and the Ticking Bomb Who Tortures? Effectiveness and Time Knowledge and Necessity The Ticking Bomb Scenario: Conclusion.

We describe a sequent calculus, based on work of Herbelin, of which the cut-free derivations are in 1-1 correspondence with the normal natural deduction proofs of intuitionistic logic. We present a simple proof of Herbelin's strong cut-elimination theorem for the calculus, using the recursive path ordering theorem of Dershowitz.

El debate acerca de la tortura puede dividirse, siguiendo la clasificación de McMahan, en dos niveles: teórico y práctico. En el primero se discute acerca de la permisibilidad moral de la tortura en circunstancias excepcionales y las características que la convierten en una práctica, prima facie, inmoral. En el segundo se evalúan las posibles consecuencias de diferentes modelos de legislación para dar una respuesta a las situaciones del mundo real. El presente trabajo se inscribe en este segundo nivel y se (...) propone analizar críticamente las propuestas legislativas de Jeff McMahan y Alan Dershowitz. Asimismo, busca ofrecer una exploración preliminar de las ventajas del modelo legalista. (shrink)

Ticking time-bomb cases famously—or infamously—invite us to imagine a scenario wherein the torture of one guilty terrorist will lead to the acquisition of information that can be used to save the lives of many innocents. Despite the contemporary focus on such cases, they have a long tradition, dating to the early 1800s. And, throughout their history, they have appeared in various guises, from the literary to the public to the philosophical. The principal moral question suggested by these cases is whether (...) one harm can be effected such that a worse one is not; while there is certainly dissent, most moral philosophers would answer this question in the affirmative. That said, there is substantial doubt as to whether torture would be the lesser harm or, more generally, whether ticking time-bomb cases gain any purchase in the real world or are otherwise relegated to philosophical fiction. But even if they gain such purchase, then what? In other words, even if torture can be morally justified in exceptional cases, should we authorize it? I n the literature—and conceptually—there are three basic approaches to authorizing torture. The first is not to authorize it at all, which is to say that torture—even if justified—requires some sort of punishable civil disobedience . Another approach is to authorize torture ex ante, such as through torture warrants. On this approach, torture remains prohibited except for when a judge grants permission for its application. Torture warrants have been defended by Alan Dershowitz, and we will evaluate that debate . Finally, torture can be legitimized ex post, which is to say that torture remains illegal but can nevertheless be justified or excused; our discussion will focus on the justifications of self-defense and necessity. (shrink)