Gerhard Schurz

Patterns of abduction

This article describes abductions as special patterns of inference to the best explanation whose structure determines a particularly promising abductive conjecture (conclusion) and thus serves as an abductive search strategy (Sect. 1). A classification of different patterns of abduction is provided which intends to be as complete as possible (Sect. 2). An important distinction is that between selective abductions, which choose an optimal candidate from given multitude of possible explanations (Sects. 3–4), and creative abductions, which introduce new theoretical models or concepts (Sects. 5–7). While selective abduction has dominated the literature, creative abductions are rarely discussed, although they are essential in science. The article introduces several kinds of creative abductions, such as theoretical model abduction, common cause abduction and statistical factor analysis, and illustrates them by various real case examples. It is suggested to demarcate scientifically fruitful abductions from purely speculative abductions by the criterion of causal unification (Sect. 7.1).

Outline of a theory of scientific understanding

The basic theory of scientific understanding presented in Sections 1–2 exploits three main ideas.First, that to understand a phenomenonP (for a given agent) is to be able to fitP into the cognitive background corpusC (of the agent).Second, that to fitP intoC is to connectP with parts ofC (via “arguments” in a very broad sense) such that the unification ofC increases.Third, that the cognitive changes involved in unification can be treated as sequences of shifts of phenomena inC. How the theory fits typical examples of understanding and how it excludes spurious unifications is explained in detail. Section 3 gives a formal description of the structure of cognitive corpuses which contain descriptive as well as inferential components. The theory of unification is then refined in the light of so called “puzzling phenomena”, to enable important distinctions, such as that between consonant and dissonant understanding. In Section 4, the refined theory is applied to several examples, among them a case study of the development of the atomic model. The final part contains a classification of kinds of understanding and a discussion of the relation between understanding and explanation.

Ceteris Paribus Laws: Classification and Deconstruction

It has not been sufficiently considered in philosophical discussions of ceteris paribus (CP) laws that distinct kinds of CP-laws exist in science with rather different meanings. I distinguish between (1.) comparative CP-laws and (2.) exclusive CP-laws. There exist also mixed CP-laws, which contain a comparative and an exclusive CP-clause. Exclusive CP-laws may be either (2.1) definite, (2.2) indefinite or (2.3) normic. While CP-laws of kind (2.1) and (2.2) exhibit deductivistic behaviour, CP-laws of kind (2.3) require a probabilistic or non-monotonic reconstruction. CP-laws of kind (1) may be both deductivistic or probabilistic. All these kinds of CP-laws have empirical content by which they are testable, except CP-laws of kind (2.2) which are almost vacuous. Typically, CPlaws of kind (1) express invariant correlations, CP-laws of kind (2.1) express closed system laws of physical sciences, and CP-laws of kind (2.3) express normic laws of non-physical sciences based on evolution-theoretic stability properties.

The Meta‐inductivist’s Winning Strategy in the Prediction Game: A New Approach to Hume’s Problem*

This article suggests a ‘best alternative’ justification of induction (in the sense of Reichenbach) which is based on meta‐induction. The meta‐inductivist applies the principle of induction to all competing prediction methods which are accessible to her. It is demonstrated, and illustrated by computer simulations, that there exist meta‐inductivistic prediction strategies whose success is approximately optimal among all accessible prediction methods in arbitrary possible worlds, and which dominate the success of every noninductive prediction strategy. The proposed justification of meta‐induction is mathematically analytical. It implies, however, an a posteriori justification of object‐induction based on the experiences in our world.

Pietroski and Rey on Ceteris Paribus Laws

In Brit. J. Phil. Sci., 46, Pietroski and Rey ([1995]) suggested a reconstruction of ceteris paribus (CP)‐laws, which — as they claim — saves CP‐laws from vacuity. This discussion note is intended to show that, although Pietroski and Reys reconstruction is an improvement in comparison to previous suggestions, it cannot avoid the result that CP‐laws are almost vacuous. It is proved that if Cx is an arbitrary (nomological) event‐type which has independently identifiable deterministic causes, then for every other (nomological) event‐type Ax which is not strictly connected with Cx or with ¬Cx, ‘CP if Ax then Cx’ satisfies the conditions of Pietroski and Rey for CP‐laws. It is also shown that Pietroski and Reys reconstruction presupposes the assumption of determinism. The conclusion points towards some alternatives to Piectroski and Reys reconstruction.

Zwart and Franssen's impossibility theorem holds for possible-world-accounts but not for consequence-accounts to verisimilitude

Zwart and Franssen’s impossibility theorem reveals a conflict between the possible-world-based content-definition and the possible-world-based likeness-definition of verisimilitude. In Sect. 2 we show that the possible-world-based content-definition violates four basic intuitions of Popper’s consequence-based content-account to verisimilitude, and therefore cannot be said to be in the spirit of Popper’s account, although this is the opinion of some prominent authors. In Sect. 3 we argue that in consequence-accounts, content-aspects and likeness-aspects of verisimilitude are not in conflict with each other, but in agreement. We explain this fact by pointing towards the deep difference between possible-world- and the consequence-accounts, which does not lie in the difference between syntactic (object-language) versus semantic (meta-language) formulations, but in the difference between ‘disjunction-of-possible-worlds’ versus ‘conjunction-of-parts’ representations of theories. Drawing on earlier work, we explain in Sect. 4 how the shortcomings of Popper’s original definition can be repaired by what we call the relevant element approach. We propose a quantitative likeness-definition of verisimilitude based on relevant elements which provably agrees with the qualitative relevant content-definition of verisimilitude on all pairs of comparable theories. We conclude the paper with a plea for consequence-accounts and a brief analysis of the problem of language-dependence (Sect. 6).

When Empirical Success Implies Theoretical Reference: A Structural Correspondence Theorem

Starting from a brief recapitulation of the contemporary debate on scientific realism, this paper argues for the following thesis: Assume a theory T has been empirically successful in a domain of application A, but was superseded later on by a superior theory T*, which was likewise successful in A but has an arbitrarily different theoretical superstructure. Then under natural conditions T contains certain theoretical expressions, which yielded Ts empirical success, such that these T-expressions correspond (in A) to certain theoretical expressions of T*, and given T* is true, they refer indirectly to the entities denoted by these expressions of T*. The thesis is first motivated by a study of the phlogiston–oxygen example. Then the thesis is proved in the form of a logical theorem, and illustrated by further examples. The final sections explain how the correspondence theorem justifies scientific realism and work out the advantages of the suggested account. 1. Introduction: Pessimistic Meta-induction vs. Structural Correspondence2. The Case of the Phlogiston Theory3. Steps Towards a Systematic Correspondence Theorem4. The Correspondence Theorem and Its Ontological Interpretation5. Further Historical Applications6. Discussion of the Correspondence Theorem: Objections and Replies7. Consequences for Scientific Realism and Comparison with Other Positions 7.1. Comparison with constructive empiricism7.2. Major difference from standard scientific realism7.3. From minimal realism and correspondence to scientific realism7.4. Comparison with particular realistic positions Introduction: Pessimistic Meta-induction vs. Structural Correspondence The Case of the Phlogiston Theory Steps Towards a Systematic Correspondence Theorem The Correspondence Theorem and Its Ontological Interpretation Further Historical Applications Discussion of the Correspondence Theorem: Objections and Replies Consequences for Scientific Realism and Comparison with Other Positions 7.1. Comparison with constructive empiricism7.2. Major difference from standard scientific realism7.3. From minimal realism and correspondence to scientific realism7.4. Comparison with particular realistic positions Comparison with constructive empiricism Major difference from standard scientific realism From minimal realism and correspondence to scientific realism Comparison with particular realistic positions

Reasoning about action and change

Reasoning about change is a central issue in research on human and robot planning. We study an approach to reasoning about action and change in a dynamic logic setting and provide a solution to problems which are related to the Frame problem. Unlike most work on the frame problem the logic described in this paper is monotonic. It (implicitly) allows for the occurrence of actions of multiple agents by introducing non-stationary notions of waiting and test. The need to state a large number of “frame axioms” is alleviated by introducing a concept of chronological preservation to dynamic logic. As a side effect, this concept permits the encoding of temporal properties in a natural way. We compare the relative merits of our approach and non-monotonic approaches as regards different aspects of the frame problem. Technically, we show that the resulting extended systems of propositional dynamic logic preserve (weak) completeness, finite model property and decidability.

Scientific explanation: A critical survey

This paper describes the development of theories of scientific explanation since Hempels earliest models in the 1940ies. It focuses on deductive and probabilistic whyexplanations and their main problems: lawlikeness, explanation-prediction asymmetries, causality, deductive and probabilistic relevance, maximal specifity and homogenity, the height of the probability value. For all of these topic the paper explains the most important approaches as well as their criticism, including the authors own accounts. Three main theses of this paper are: (1) Both deductive and probabilistic explanations are important in science, not reducible to each other. (2) One must distinguish between (cause giving) explanations and (reason giving) justifications and predictions. (3) The adequacy of deductive as well as probabilistic explanations is relative to a pragmatically given background knowledge-which does not exclude, however, the possibility of purely semantic models.

Causality as a theoretical concept: explanatory warrant and empirical content of the theory of causal nets

We start this paper by arguing that causality should, in analogy with force in Newtonian physics, be understood as a theoretical concept that is not explicated by a single definition, but by the axioms of a theory. Such an understanding of causality implicitly underlies the well-known theory of causal (Bayes) nets (TCN) and has been explicitly promoted by Glymour (Br J Philos Sci 55:779–790, 2004). In this paper we investigate the explanatory warrant and empirical content of TCN. We sketch how the assumption of directed cause–effect relations can be philosophically justified by an inference to the best explanation. We then ask whether the explanations provided by TCN are merely post-facto or have independently testable empirical content. To answer this question we develop a fine-grained axiomatization of TCN, including a distinction of different kinds of faithfulness. A number of theorems show that although the core axioms of TCN are empirically empty, extended versions of TCN have successively increasing empirical content.