Wolfgang Spohn

ISIPTA Conference 2025 Conference Paper

Rank-based decision theory and conditional deontic logic

• Wolfgang Spohn

Ranking theory is a well-established account of rational belief (= taking to be true) and its dynamics. Each formal representation of epistemic states should be extendable to a decision theory; ultimately, beliefs manifest themselves in rational action. However, the decision-theoretic extension of ranking theory is wanting. Giang and Shenoy’s “A Qualitative Linear Utility Theory for Spohn’s Theory of Epistemic Beliefs” (2000) is the only proposal so far. This paper will modify this proposal. The modification allows building a bridge to the field of (conditional) deontic logic, indeed advancing this field and thus instructing legal theory. This is to show that the modification is a fruitful one deserving further investigation and application.

FLAP Journal 2024 Journal Article

Inductive Reasoning, Conditionals, and Belief Dynamics

• Gabriele Kern-Isberner
• Wolfgang Spohn

This paper presents a broad view on inductive reasoning by embedding it in theories of epistemic states, conditionals, and belief revision. More precisely, we consider inductive reasoning as a specific case of belief revision on epistemic states which include conditionals as a basic means for representing beliefs. We present a general framework for inductive reasoning from conditional belief bases that also allows for taking background beliefs into account, and illustrate this by probabilistic reasoning based on optimum entropy as well as by ranking- theoretic reasoning based on so-called c-revision. We explain the philosophical perspective behind our approach, and we illustrate its constructive usefulness as well as its integrating power.

AIJ Journal 2008 Journal Article

The measurement of ranks and the laws of iterated contraction

• Matthias Hild
• Wolfgang Spohn

Ranking theory delivers an account of iterated contraction; each ranking function induces a specific iterated contraction behavior. The paper shows how to reconstruct a ranking function from its iterated contraction behavior uniquely up to multiplicative constant and thus how to measure ranks on a ratio scale. Thereby, it also shows how to completely axiomatize that behavior. The complete set of laws of iterated contraction it specifies amend the laws hitherto discussed in the literature.

TARK Conference 2003 Conference Paper

Enumerative induction

• Wolfgang Spohn

The paper explainsenumerativeinduction, the confirmationof a law by its positive instances, in ranking theoretic terms. It gives a ranking theoretic explication of a possible law or a nomological hypothesis. And it shows, finally, that such schemesof enumerativeinductionuniquelycorrespondto mixturesof such nomological hypotheses. Thus the paper shows that de Finettl's probabilistic representation theorems may be directly transformed into an account of confirmation of possible laws andthatenumerativeinductionis equivalentto suchan account.

UAI Conference 1988 Conference Paper

A general non-probabilistic theory of inductive reasoning

• Wolfgang Spohn