Wilfred Sieg. Mechanical Procedures and Mathematical Experience.

Hilbert's finitist program was not created at the beginning of the twenties solely to counteract Brouwer's intuitionism, but rather emerged out of broad philosophical reflections on the foundations of mathematics and out of detailed logical work; that is evident from notes of lecture courses that were given by Hilbert and prepared in collaboration with Bernays during the period from 1917 to 1922. These notes reveal a dialectic progression from a critical logicism through a radical constructivism toward finitism; the progression has (...) to be seen against the background of the stunning presentation of mathematical logic in the lectures given during the winter term 1917/18. In this paper, I sketch the connection of Hilbert's considerations to issues in the foundations of mathematics during the second half of the 19th century, describe the work that laid the basis of modern mathematical logic, and analyze the first steps in the new subject of proof theory. A revision of the standard view of Hilbert's and Bernays's contributions to the foundational discussion in our century has long been overdue. It is almost scandalous that their carefully worked out notes have not been used yet to understand more accurately the evolution of modern logic in general and of Hilbert's Program in particular. One conclusion will be obvious: the dogmatic formalist Hilbert is a figment of historical (de)construction! Indeed, the study and analysis of these lectures reveal a depth of mathematical-logical achievement and of philosophical reflection that is remarkable. In the course of my presentation many questions are raised and many more can be explored; thus, I hope this paper will stimulate interest for new historical and systematic work. (shrink)

This book represents a considerable revision and expansion of Public Choice II. Six new chapters have been added, and several chapters from the previous edition have been extensively revised. The discussion of empirical work in public choice has been greatly expanded. As in the previous editions, all of the major topics of public choice are covered. These include: why the state exists, voting rules, federalism, the theory of clubs, two-party and multiparty electoral systems, rent seeking, bureaucracy, interest groups, dictatorship, the (...) size of government, voter participation, and political business cycles. Normative issues in public choice are also examined including a normative analysis of the simple majority rule, Bergson–Samuelson social welfare functions, the Arrow and Sen impossibility theorems, Rawls's social contract theory and the constitutional political economy of Buchanan and Tullock. (shrink)

The incompleteness theorems constitute the mathematical core of Gödel’s philosophical challenge. They are given in their “most satisfactory form”, as Gödel saw it, when the formality of theories to which they apply is characterized via Turing machines. These machines codify human mechanical procedures that can be carried out without appealing to higher cognitive capacities. The question naturally arises, whether the theorems justify the claim that the human mind has mathematical abilities that are not shared by any machine. Turing admits that (...) non-mechanical steps of intuition are needed to transcend particular formal theories. Thus, there is a substantive point in comparing Turing’s views with Gödel’s that is expressed by the assertion, “The human mind infinitely surpasses any finite machine”. The parallelisms and tensions between their views are taken as an inspiration for beginning to explore, computationally, the capacities of the human mathematical mind. (shrink)

A survey of Euclid's Elements, this text provides an understanding of the classical Greek conception of mathematics and its similarities to modern views as well as its differences. It focuses on philosophical, foundational, and logical questions — rather than strictly historical and mathematical issues — and features several helpful appendixes.

Essays discuss reason and understanding, interpretation, language, meaning, the human sciences, social sciences, and general hermeneutic theory.

Recently, Kenneth Westphal has presented a highly interesting and innovative reading of Kant's critical philosophy.2 This reading continues a tradition of Kantscholarship of which, e.g., Paul Guyer's work is representative, and in which the antiidealistic potential of Kant's critical philosophy is pitted against its idealistic selfunderstanding. Much of the work in this tradition leaves matters at observing the tensions this introduces in Kant's work. But Westphal's proposed interpretation goes farther. Its attractiveness derives for the most part from the promise that (...) it permits an internal critique of Kant's transcendental idealism (TI), that is, a critique that is based on the very resources of Kantian transcendental philosophy.3 In contrast to these resources, which currently seem to go through a sort of revival in an enormous array of fields, TI is notorious for dismaying even sympathetic interpreters. How attractive and needed such an internal critique of TI would be becomes all the more patent when we place such a promise in the context of some of the contemporary discussions about TI after Allison's famous defense of it. Before directly engaging with Westphal's interpretation, I would therefore like to quickly sketch on what background it acquires its force (I). After characterizing the main features of Westphal's view (II), and supporting it in more detail by an account of Kant's theory of cognitive significance (III), I then want to review the extent of its success to present Kant as issuing an anti-skeptical argument (IV.1), or semantic views that are incompatible with TI (IV.2), or a 'proof of not merely empirical realism' (IV.3). I agree that purely idealist readings of Kant are mistaken. Westphal's... (shrink)

This article draws on ethnographic field data collected during an investigation of the informed consent process and AIDS clinical trials. It describes the involvement of care providers (physicians, nurse practitioners, physician assistants) during the enlistment, or recruitment, phase of the informed consent process. It shows that sometimes care providers are involved in the receipt, evaluation and distribution of information on clinical trials through their interactions with research professionals and patients. It suggests that the involvement of care providers has the potential (...) to influence the informed consent process. Some of the ethical and practice considerations of this are discussed. (shrink)

David Hilbert was one of the great mathematicians who expounded the centrality of their subject in human thought. In this collection of essays, Wilfried Sieg frames Hilbert's foundational work, from 1890 to 1939, in a comprehensive way and integrates it with modern proof theoretic investigations.

Mueller et al. discuss the role of acoustic cues in detecting language structure more generally. Across languages, there are clear links between acoustic cues and syntactic structure. They show that AGL experiments implementing analogous links demonstrate that prosodic cues, as well as various auditory biases, facilitate the learning of structural rules. Some of these biases, e.g. for auditory grouping, are also present in other species.

Wilfried Sieg. Formal Systems, Church Turing Thesis, and Gödel's Theorems: Three Contributions to The MIT Encyclopedias of Cognitive Science.

In this book, Andy Mueller examines the ways in which epistemic and practical rationality are intertwined. In the first part, he presents an overview of the contemporary debates about epistemic norms for practical reasoning, and defends the thesis that epistemic rationality can make one practically irrational. Mueller proposes a contextualist account of epistemic norms for practical reasoning and introduces novel epistemic norms pertaining to ends and hope. In the second part Mueller considers current approaches to pragmatic encroachment in epistemology, ultimately (...) arguing in favor of a new principle-based argument for pragmatic encroachment. While the book defends tenets of the knowledge-first programme, one of its main conclusions is thoroughly pragmatist: in an important sense, the practical has primacy over the epistemic. (shrink)

Wilfried Sieg and John Byrnes. AnModel for Parallel Computation: Gandy's Thesis.

Wilfried Sieg. Calculations by Man and Machine: Mathematical Presentation.

Natural deduction (for short: nd-) calculi have not been used systematically as a basis for automated theorem proving in classical logic. To remove objective obstacles to their use we describe (1) a method that allows to give semantic proofs of normal form theorems for nd-calculi and (2) a framework that allows to search directly for normal nd-proofs. Thus, one can try to answer the question: How do we bridge the gap between claims and assumptions in heuristically motivated ways? This informal (...) question motivates the formulation of intercalation calculi. Ic-calculi are the technical underpinnings for (1) and (2), and our paper focuses on their detailed presentation and meta-mathematical investigation in the case of classical predicate logic. As a central theme emerges the connection between restricted forms of nd-proofs and (strategies for) proof search: normal forms are not obtained by removing local "detours", but rather by constructing proofs that directly reflect proof-strategic considerations. That theme warrants further investigation. (shrink)

In this article we give a unifying approach to the theory of fundamental sequences and their related Hardy hierarchies of number-theoretic functions and we show the equivalence of the new approach with the classical one.

It is a popular thought that emotions play an important epistemic role. Thus, a considerable number of philosophers find it compelling to suppose that emotions apprehend the value of objects and events in our surroundings. I refer to this view as the Epistemic View of emotion. In this paper, my concern is with a rivaling picture of emotion, which has so far received much less attention. On this account, emotions do not constitute a form of epistemic access to specific axiological (...) aspects of their objects. Instead it proposes that they are ways of taking a stand or position on the world. I refer to this as the Position-Taking View of emotion. Whilst some authors seem sympathetic to this view, this it has so far not been systematically motivated and elaborated. In this paper, I fill this gap and propose a more adequate account of our emotional engagement with the world than the predominant epistemic paradigm. I start by highlighting the specific way in which emotions are directed at something, which I contrast with the intentionality of perception and other forms of apprehension. I then go on to offer a specific account of the valence of emotion and show how this account and the directedness of emotions makes them intelligible as a way of taking a position on something. (shrink)

The Hygiene Hypothesis has been recognized as an important cornerstone to explain the sudden increase in the prevalence of asthma and allergic diseases in modernized culture. The recent epidemic of allergic diseases is in contrast with the gradual implementation of Homo sapiens sapiens to the present-day forms of civilization. This civilization forms a gradual process with cumulative effects on the human immune system, which co-developed with parasitic and commensal Helminths. The clinical manifestation of this epidemic, however, became only visible in (...) the second half of the twentieth century. In order to explain these clinical effects in terms of the underlying IgE-mediated reactions to innocuous environmental antigens, the low biodiversity of antigens in the domestic environment plays a pivotal role. The skewing of antigen exposure as a cumulative effect of reducing biodiversity in the immediate human environment as well as in changing food habits, provides a sufficient and parsimonious explanation for the rise in allergic diseases in a highly developed and helminth-free modernized culture. Socio-economic tendencies that incline towards a further reduction of environmental biodiversity may provide serious concern for future health. This article explains that the “Hygiene Hypothesis”, the “Old Friends Hypothesis”, and the “Skewed Antigen Exposure Hypothesis” are required to more fully explain the rise of allergy in modern societies. (shrink)

Zuerst im 2CV, dann im umgebauten VW-Bus: Das Zürcher Fotografenpaar Margrit und Ernst Baumann, 1929 bzw. 1928 geboren, begann in den 1950er-Jahren rund um den Erdball zu reisen. Ihre Fotografien publizierten sie in Zeitschriften und Zeitungen wie Stern, Neue Zürcher Zeitung oder Das gelbe Heft und brachten so die Welt in die Wohnzimmer. Kosmopolitan und neugierig kamen sie zu Motiven mit Seltenheitswert: Farbporträts von Che Guevara gehören ebenso dazu wie Reportagen über die letzten Kopfjäger im ecuadorianischen Urwald. Ein Schwerpunkt dieser (...) reich bebilderten Doppelmonografie ist ihre Reise entlang der “Panamericana” 1957-1959, die Süd- und Nordamerika verbindet. Sie fotografierten Reportagen, Porträts und Landschaftsbilder und drehten den wohl ersten Farbfilm über den legendären Verkehrsweg. Dieser Film und ein Filporträt über die beiden Fotografen sind dem Buch auf DVD beigefügt. Das Buch präsentiert Funde aus ihrem Fotoarchiv - viele Bilder erstmals im Originalausschnitt - sowie Publikationen in Zeitschriften. Der Historiker und Schriftsteller Wilfried Meichtry erzählt vom ereignisreichen Leben des Paars, das sich zeitlebens als journalistische Handwerker verstanden hat. Der Fotohistoriker Markus Schürpf ordnet ihr Werk in die Foto- und Pressegeschichte ein, Nadine Olonetzky verfasst Begleittexte zu den Bildern. Eine Entdeckung in der Schweizer Fotogeschichte. (shrink)

Wilfred Sieg and Dirk Schlimm. Dedekind's Analysis of Number: Systems and Axioms.

Herbrand's Theorem, in the form of $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{\exists } $$ -inversion lemmata for finitary and infinitary sequent calculi, is the crucial tool for the determination of the provably total function(al)s of a variety of theories. The theories are (second order extensions of) fragments of classical arithmetic; the classes of provably total functions include the elements of the Polynomial Hierarchy, the Grzegorczyk Hierarchy, and the extended Grzegorczyk Hierarchy $\mathfrak{E}^\alpha $ , α < ε0. A subsidiary aim of the paper is to show (...) that the proof theoretic methods used here are distinguished by technical elegance, conceptual clarity, and wide-ranging applicability. (shrink)

Religious sects and their practices have become highly topical in the recent past in Germany. The call for criminal sanctions in order to tackle actual or presumed misconduct is becoming louder and louder. The author, a criminal law professor, analyses the present discussion and puts it into a constitutional law perspective. Any civil society that aims to optimise the scope of the personal freedoms of its members must withstand the temptation of creating a special regime of criminal law rules just (...) to combat religious sects and their practices. Criminal law has tobe applied uniformly in the whole society. Therfore, criminal sanctions can only be handed out, when practices infringe intolerably with the individual' s rights protected by the law. (shrink)

Results from an opinion poll, held in mid-year 1975, with a representative sample of Belgian citizens, show that the oppositions the citizens perceive, are partly of a universal nature and partly specifically Belgian. Those who have gat power vs. those who have not, young vs. old, male vs. female are oppositions that complement more specifically Belgian conflict dimensions : socio-economic problems, religion, ethnicity. The political parties are instrumental towards some poles on such confiict dimensions, but the instrumentality is not yet (...) proportionalto the share of the poles in the total population; moreover, it is quite weak towards some poles. The image the public has about the power hierarchy in Belgium appears to coincide rather adequately with a ranking on the power hierarchy as established by the top-participants. People do realize who really is powerful. Besides, the basic institutions of parliamentary democracy are fundamentally recognized and accepted. One finds indeed quite unambiguous appreciations of the individual and social rights and freedoms, of the institutionalization of conflict solution and of the maintenance of the political entity. (shrink)

The political debate in Western polyarchies readily points to a «Parteienstaat», «particrazia», or particracy. Empirical verification, however, is by far more difficult to carry out, though it is a descriptive necessity for further analysis of this phenomenon.An initial attempt to detect the particraties in Western Europe has been performed and revealed two particracies : Belgium and Italy. Other polyarchies have either the cabinet or the president as the most influential actor, an,d some seem to have a real concurrence of approximately (...) equivalent actors. The reliability of this first attempt, however, must be improved. (shrink)