This volume will be of particular interest to researchers working in the history, and in the philosophy, of logic and mathematics, and more generally, to ...

Essays on Husserl’s Logic and Philosophy of Mathematics sets out to fill up a lacuna in the present research on Husserl by presenting a precise account of Husserl’s work in the field of logic, of the philosophy of logic and of the philosophy of mathematics. The aim is to provide an in-depth reconstruction and analysis of the discussion between Husserl and his most important interlocutors, and to clarify pivotal ideas of Husserl’s by considering their reception and elaboration by some of (...) his disciples and followers, such as Oskar Becker and Jacob Klein, as well as their influence on some of the most significant logicians and mathematicians of the past century, such as Luitzen E. J. Brouwer, Rudolf Carnap, Kurt Gödel and Hermann Weyl. Most of the papers consider Husserl and another scholar – e.g. Leibniz, Kant, Bolzano, Brentano, Cantor, Frege – and trace out and contextualize lines of influence, points of contact, and points of disagreement. Each essay is written by an expert of the field, and the volume includes contributions both from the analytical tradition and from the phenomenological one. (shrink)

Two hundred years ago Bernard Bolzano published a booklet on the philosophy of mathematics that is the first major step forward in this area since Pascal’s De l’esprit géométrique. Following Aristotelian lines Bolzano distinguishes in his opusculum two kinds of proofs, those that simply show that something is the case, and those that explain why something is the case. In his Wissenschaftslehre this contrast reappears as that between derivability and consecutivity . Husserl takes up some of Bolzano’s key concepts in (...) his Prolegomena to Pure Logic. In this paper I discuss, among other things, the question whether consecutivity can be regarded as a special case of derivability, as Husserl seems to think, and I contrast Bolzano’s rejection of any appeal to self-evidence with Husserl’s reliance on this notion.Genau vor zweihundert Jahren erschienen Bernard Bolzano Beyträge zu einer begründeteren Darstellung der Mathematik. Dieses Büchlein ist der erste Meilenstein in der Geschichte der Philosophie der Mathematik seit Pascals De l’esprit géométrique. Im Anschluss an Aristoteles unterscheidet Bolzano in seinem Opusculum zwei Arten von Beweisen: solche, die nur dartun, dass etwas der Fall ist, und solche, die erklären warum etwas der Fall ist. Im seiner Wissenschaftslehre erscheint dieser Kontrast als der zwischen Ableitbarkeit und Abfolge. Husserl übernimmt einige von Bolzanos Grundbegriffen in seinen Prolegomena zur reinen Logik. In diesem Aufsatz diskutiere ich u.a. die Frage, ob Abfolge ein Spezialfall von Ableitbarkeit ist, wie Husserl anzunehmen scheint, und ich kontrastiere Bolzanos Ablehnung jeder Berufung auf Evidenz mit Husserls Einstellung. (shrink)

This edited work presents contemporary mathematical practice in the foundational mathematical theories, in particular set theory and the univalent foundations. It shares the work of significant scholars across the disciplines of mathematics, philosophy and computer science. Readers will discover systematic thought on criteria for a suitable foundation in mathematics and philosophical reflections around the mathematical perspectives. The first two sections focus on the two most prominent candidate theories for a foundation of mathematics. Readers may trace current research in set theory, (...) which has widely been assumed to serve as a framework for foundational issues, as well as new material elaborating on the univalent foundations, considering an approach based on homotopy type theory (HoTT). The further sections then build on this and are centred on philosophical questions connected to the foundations of mathematics. Here, the authors contribute to discussions on foundational criteria with more general thoughts on the foundations of mathematics which are not connected to particular theories. This book shares the work of some of the most important scholars in the fields of set theory (S. Friedman), non-classical logic (G. Priest) and the philosophy of mathematics (P. Maddy). The reader will become aware of the advantages of each theory and objections to it as a foundation, following the latest and best work across the disciplines and it is therefore a valuable read for anyone working on the foundations of mathematics or in the philosophy of mathematics. (shrink)

This paper analyzes and evaluates Bolzano's remarks on the apagogic method of proof with reference to his juvenile booklet "Contributions to a better founded presentation of mathematics" of 1810 and to his ?Theory of science? (1837). I shall try to defend the following contentions: (1) Bolzanos vain attempt to transform all indirect proofs into direct proofs becomes comprehensible as soon as one recognizes the following facts: (1.1) his attitude towards indirect proofs with an affirmative conclusion differs from his stance to (...) indirect proofs with a negative conclusion; (1.2) by Bolzano's lights arguments via consequentia mirabilis only seem to be indirect. (2) Bolzano does not deny that indirect proofs can be perfect certifications (Gewissmachungen) of their conclusion; what he denies is rather that they can provide grounds for their conclusions. (2.1) They cannot do the latter, since they start from false premises and (2.2) since they make an unnecessary detour. (3) The far-reaching agreement between his early and late assessment of apagogical proofs (in the Beyträge of 1810 and the Wissenschaftslehre of 1837) is partly due to the fact that he develops his own position always against the background of Wolff's and Lambert's views. (shrink)

This explorative article is organized around a set of questions concerning the concept of a function. First, a summary of certain general facts about functions that are a common coin in contemporary logic is given. Then Frege's attempt at clarifying the nature of functions in his famous paper Function and Concept and in his Grundgesetze is discussed along with some questions which Freges' approach gave rise to in the literature. Finally, some characteristic uses of functional notions to be found in (...) the work of Bernard Bolzano and in Edmund Husserl's early work are presented and elucidated. (shrink)

At a time when they had largely fallen into disrepute Bolzano reactivated the distinctions between ‚clear‘ and ‚obscure‘, ‚distinct‘ and ‚confused‘ ideas. In the central sections of this paper I offer a critical reconstruction of the explanations of these pairs of opposita which are to be found in vol. III of Bolzano's monumental Wissenschaftslehre . I then provide a detailed account of its Leibnizian counterparts that were well-known to the ‚Bohemian Leibniz‘, and finally I evaluate Bolzano's criticism thereof.

In the present paper, we discuss Husserl's deep account of the notions of ?calculation? and of arithmetical ?operation? which is found in the final chapter of the Philosophy of Arithmetic, arguing that Husserl is as far as we know the first scholar to reflect seriously on and to investigate the problem of circumscribing the totality of computable numerical operations. We pursue two complementary goals, namely: (i) to provide a formal reconstruction of Husserl's intuitions, and (ii) to demonstrate on the basis (...) of our reconstruction that the class of operations that Husserl has in mind turns out to be extensionally equivalent to the one that, in contemporary logic, is known as the class of partial recursive functions. (shrink)

Two centuries ago Bernard Bolzano published his Contributions to a more well-founded presentation of mathematics which Goethe praised as “an opusculum of very high value”. Bolzano still seems to accept the traditional principle that that intension and extension of a concept stand in an inverse relation . In particular he claims that the concept of a genus proximum is always a component of the concept of the species which are subordinated to it. However, this does not harmonize with his simultaneous (...) assumption that there are simple species-concepts. In section 1 of this paper I shall try to bring to light this tension in Bolzanos Contributions. In section 2 I shall try to reconstruct Bolzano ’s arguments to the effect that the properties an object must have if it is to fall under a certain concept are not always components of that concept. In section 3 I shall try to reconstructs his arguments against the Canon in his Theory of Science .In seinen vor zwei Jahrhunderten erschienenen Beyträgen zu einer begründeteren Darstellung der Mathematik, die Goethe als „ein Werkchen von besonderem Werte“ pries, scheint Bernard Bolzano den traditionellen Lehrsatz der Reziprozität noch zu akzeptieren, demzufolge Inhalt und Umfang eines Begriffs in inversem Verhältnis stehen. Insbesondere akzeptiert er die traditionelle These, dass der Begriff eines genus proximum immer ein Bestandteil der Begriffe der Spezies dieses Genus ist. Diese Annahme schient aber im Gegensatz zu seiner gleichzeitigen Akzeptanz der These zu stehen, dass es einfache Spezies-Begriffe gibt. Im Paragraphen 1 bespreche ich diese Frage. Im Paragraphen 2 versuche ich, einige der Argumente zu rekonstruieren, die Bolzano in seiner Wissenschaftslehre zur Widerlegung der These verwendet, dass die Begriffe der Beschaffenheiten, die ein Gegenstand haben muss, um unter einen bestimmten Begriff zu fallen, immer Teile dieses Begriffs sind. Im Paragraphen 3 präsentiere ich die wichtigsten Argumente Bolzanos, die in der Wissenschaftslehre dafür verwendet werden, um den Kanon Allgemeingültigkeit abzusprechen. (shrink)

In his booklet "Contributions to a better founded presentation of mathematics" of 1810 Bernard Bolzano made his first serious attempt to explain the notion of a rigorous proof. Although the system of logic he employed at that stage is in various respects far below the level of the achievements in his later Wissenschaftslehre, there is a striking continuity between his earlier and later work as regards the methodological constraints on rigorous proofs. This paper tries to give a perspicuous and critical (...) account of the fragmentary logic of Beyträge, and it shows that there is a tension between that logic and Bolzano's methodological ban on ?kind crossing? (shrink)

Name der Zeitschrift: Archiv für Geschichte der Philosophie Jahrgang: 97 Heft: 1 Seiten: 66-96.

It is well known that Husserl, together with Plato and Leibniz, counted among Gödel’s favorite philosophers and was, in fact, an important source and reference point for the elaboration of Gödel’s own philosophical thought. Among the scholars who emphasized this connection we find, as Richard Tieszen reminds us, Gian-Carlo Rota, George Kreisel, Charles Parsons, Heinz Pagels and, especially, Hao Wang. Right at the beginning of After Gödel we read: “The logician who conducted and recorded the most extensive philosophical discussions with (...) Kurt Gödel during Gödel’s later years was Hao Wang” .This book takes Wang’s report about Gödel’s philosophical interests seriously and paves the way “to go beyond the contributions of Plato, Leibniz and Husserl, based on Gödel’s philosophical and technical writings, his comments to Hao Wang, and various items from the Gödel Nachlass” . Tieszen proposes a “type of Gödelian platonic rationalism” about mathematic and logic that makes no pretenc .. (shrink)

In his booklet ‘Contributions to a better founded presentation of mathematics’ of 1810 Bernard Bolzano made his first serious attempt to explain the notion of a rigorous proof. Although the system of logic he employed at that stage is in various respects far below the level of the achievements in his later Wissenschaftslehre, there is a striking continuity between his earlier and later work as regards the methodological constraints on rigorous proofs. This paper tries to give a perspicuous and critical (...) account of the fragmentary logic of Beyträge, and it shows that there is a tension between that logic and Bolzano's methodological ban on ‘kind crossing’. (shrink)

This paper analyzes and evaluates Bolzano's remarks on the apagogic method of proof with reference to his juvenile booklet ‘Contributions to a better founded presentation of mathematics’ of 1810 and to his ‘Theory of science’. I shall try to defend the following contentions: Bolzanos’ vain attempt to transform all indirect proofs into direct proofs becomes comprehensible as soon as one recognizes the following facts: his attitude towards indirect proofs with an affirmative conclusion differs from his stance to indirect proofs with (...) a negative conclusion; by Bolzano's lights arguments via consequentia mirabilis only seem to be indirect. Bolzano does not deny that indirect proofs can be perfect certifications of their conclusion; what he denies is rather that they can provide grounds for their conclusions. They cannot do the latter, since they start from false premises and since they make an unnecessary detour. The far-reaching agreement between his early and late assessment of apagogical proofs is partly due to the fact that he develops his own position always against the background of Wolff's and Lambert's views. (shrink)

We aim at clarifying to what extent the work of the German mathematician Ernst Schröder on the algebra of logic is taken into consideration and rehashed in the work of the early Husserl, focusing on Husserl’s 1891 Review of the first volume of Schröder’s monumental Vorlesungen über die Algebra der Logik and on Husserl’s text Der Folgerungskalkül und die Inhaltslogik written in the same year. We will try to show how and why Husserl, while praising Schröder’s calculus, strongly criticizes Schröder’s (...) attempt at a philosophical clarification and justification of it. (shrink)

In a fragment entitled Elementa Nova Matheseos Universalis Leibniz writes “the mathesis [...] shall deliver the method through which things that are conceivable can be exactly determined”; in another fragment he takes the mathesis to be “the science of all things that are conceivable.” Leibniz considers all mathematical disciplines as branches of the mathesis and conceives the mathesis as a general science of forms applicable not only to magnitudes but to every object that exists in our imagination, i.e. that is (...) possible at least in principle. As a general science of forms the mathesis investigates possible relations between “arbitrary objects”. It is an abstract theory of combinations and relations among objects whatsoever. In 1810 the mathematician and philosopher Bernard Bolzano published a booklet entitled Contributions to a Better-Grounded Presentation of Mathematics. There is, according to him, a certain objective connection among the truths that are germane to a certain homogeneous field of objects: some truths are the “reasons” of others, and the latter are “consequences” of the former. The reason-consequence relation seems to be the counterpart of causality at the level of a relation between true propositions. Arigorous proof is characterized in this context as a proof that shows the reason of the proposition that is to be proven. Requirements imposed on rigorous proofs seem to anticipate normalization results in current proof theory. The contributors of Mathesis Universalis, Computability and Proof, leading experts in the fields of computer science, mathematics, logic and philosophy, show the evolution of these and related ideas exploring topics in proof theory, computability theory, intuitionistic logic, constructivism and reverse mathematics, delving deeply into a contextual examination of the relationship between mathematical rigor and demands for simplification. (shrink)

The notion of mathesis universalis appears in many of Edmund Husserl’s works, where it corresponds essentially to “a universal a priori ontology”. This paper has two purposes; one, largely exegetical, of clarifying how Husserl elaborates on Leibniz’ concept of mathesis universalis and associated notions like symbolic thinking and symbolic knowledge filtering them through the lesson of the so called “bohemian Leibniz”, Bernard Bolzano; another, more properly philosophical, of examining the role that the universal mathesis is allowed to play, and the (...) space it occupies in Husserl’s intuition-based epistemology. (shrink)

There are quite a few studies on late Bolzano’s notion of a collection. We try to broaden the perspective by introducing the forerunner of collections in Bolzano’s early writings, namely the entities referred to by expressions with the technical term ‘et’. Special emphasis is laid on the question whether these entities are set-theoretical or mereological plenties. Moreover, similarities and differences to Bolzano’s mature conception are pointed out.

This paper analyzes Mally’s system of deontic logic, introduced in his The Basic Laws of Ought: Elements of the Logic of Willing (1926). We discuss Mally’s text against the background of some contributions in the literature which show that Mally’s axiomatic system for deontic logic is flawed, in so far as it derives, for an arbitrary A, the theorem “A ought to be the case if and only if A is the case”, which represents a collapse of obligation. We then (...) try to sort out and understand which axioms are responsible for the collapse and consider two ways of amending Mally’s system: (i) by changing its original underlying logical basis, that is classical logic, and (ii) by modifying Mally’s axioms. (shrink)

We aim at clarifying to what extent the work of the English mathematician George Boole on the algebra of logic is taken into consideration and discussed in the work of early Husserl, focusing in particular on Husserl’s lecture “Über die neueren Forschungen zur deduktiven Logik” of 1895, in which an entire section is devoted to Boole. We confront Husserl’s representation of the problem-solving processes with the analysis of “symbolic reasoning” proposed by George Boole in the Laws of Thought and try (...) to show how and why Husserl, while praising Boole’s calculus, strongly criticizes his attempt at a philosophical clarification and justification of it. (shrink)