This volume is dedicated to Paul Weingartner in acknowledgement of his outstanding contribution to the advancement of scientifically oriented philosophy. The volume is arranged in several sections and subsections (see table of contents). Subsection I.1 focuses on relevance in logic, an area in logic which Paul Weingartner has found increasingly appealing over the last ten years. SYLVAN AND NOLA show how certain ways of strengthening relevance logic resolve most of the paradoxes of confirmation. In addition, they discuss striking similarities as well as differences between their work and that of Weingartner. SCHURZ’s paper includes a reply to Sylvan and Nola, a discussion of the approaches of Orlowska/Weingartner and of Smith, and new findings on Weingartner’s Aristotelian criterion and on the replacement criterion of Schurz and Weingartner.

In several papers, Weingartner has argued that an adequate epistemic logic must not entail logical omniscience. The three contributions in subsection I.2 follow Weingartner’s admonition. DALLA CHIARA extends first-order predicate logic to an axiomatic epistemic logic. GOCHET AND GILLET improve Weingartner’s attempt to construct a realistic epistemic logic by setting up axiomatic systems of weak multi-agent knowledge within T, S4 and S5. FESTINI applies Weingartner’s results to Wittgenstein’s sporadic remarks on knowledge and belief.

Subsection II.1 deals with the question whether quantum theory is compatible with a realist notion of objectivity. ENZ evaluates modern experiments in quantum physics, with the conclusion that the quantum objects have the freedom of being potentially both particle and field, located and moving, before they are measured. MITTELSTÄDT defines two versions of the objectivity hypothesis in quantum mechanics. He presents several theorems which imply that both versions are false. SCHEIBE shows that quantum theory has significant implications for the ontological notions of substance and predication, independence and individuality.

In subsection II.2, STÖCKLER presents a philosophical analysis of modern theories of self-organization. They force us to reject methodological reductionism, as Stöckler argues, but not ontological reductionism. KANITSCHEIDER distinguishes between epistemological unity of science and ontological unity of reality. He argues for both.

In subsection II.3, PRZELECKI shows how the gap between the traditional view of theories as sets of statements and the structuralist view of theories as sets of set- theoretical structures can be bridged. KUIPERS uses his notion of verisimilitude, expressed in a structuralist framework, to give a rational reconstruction of certain dialectical concepts. MOULINES replies to Paul Weingartner’s recent criticism of the structuralist view of scientific theories.

Subsection II.4 starts with a contribution by POPPER, in which he explains and defends his theory of propensities. As is well known, Popper argued in the 1980s that probabilistic support is not inductive. DORN makes a rigorous reconstruction of this argument by setting up two axiomatic theories of inductive support and by deriving an anti-induction theorem within each of these theories.

In section III, KUTSCHERA delivers a stringent refutation of Kripke’s scepticism about the meaning of rules. SIMONS uses Weingartner’s theory of intension and extension to illustrate his own view that the notions of extension and intension do not allow an adequate understanding of meaning. MORSCHER adds some critical remarks to both Weingartner’s and Simons’ thoughts on extension and intension. In his paper on the ‘slingshot’ argument, BRANDL comes to the conclusion that the meaning of a declarative sentence should be taken neither as truth-value, nor as a proposition but as a bundle of facts. Finally, HIEKE discusses Paul Weingartner’s theory of real facts.

Section IV collects papers on social aspects of belief and action. KLEVAKINA argues that belief stands in extrinsic and intrinsic relations to values. TUOMELA gives a detailed analysis of the structure of iterated mutual beliefs within human social relationships. LENK and MARING as well as NEUMAIER try to answer the question who is responsible for the outcomes of collective actions and how the responsibility of a collective can be distributed among its members.

In Section V, BOCHENSKI gives a subtle logical commentary on the first question of the Summa Theologiae. NIEZNANSKI surveys the history of formal approaches to the philosophy of religion, with special attention to Weingartner’s writings on the subject. GANTHALER argues against Weingartner’s claim that theology is a science.

In section VI, KREISEL considers various fields of mathematics and science and investigates the conditions under which a description of a philosophical or scientific problem may become heuristically productive. All his arguments and remarks are related to personal discussions between himself and Paul Weingartner. BUNGE cherishes exactness, whereas KOJ expresses reservations about it.