Contrastive Explanations of Plans through Model Restrictions

In automated planning, the need for explanations arises when there is a mismatch between a proposed plan and the user’s expectation. We frame Explainable AI Planning as an iterative plan exploration process, in which the user asks a succession of contrastive questions that lead to the generation and solution of hypothetical planning problems that are restrictions of the original problem. The object of the exploration is for the user to understand the constraints that govern the original plan and, ultimately, to arrive at a satisfactory plan. We present the results of a user study that demonstrates that when users ask questions about plans, those questions are usually contrastive, i.e. “why A rather than B?”. We use the data from this study to construct a taxonomy of user questions that often arise during plan exploration. Our approach to iterative plan exploration is a process of successive model restriction. Each contrastive user question imposes a set of constraints on the planning problem, leading to the construction of a new hypothetical planning problem as a restriction of the original. Solving this restricted problem results in a plan that can be compared with the original plan, admitting a contrastive explanation. We formally define model-based compilations in PDDL2.1 for each type of constraint derived from a contrastive user question in the taxonomy, and empirically evaluate the compilations in terms of computational complexity. The compilations were implemented as part of an explanation framework supporting iterative model restriction. We demonstrate its benefits in a second user study.

Could Science be Interestingly Different?

In this paper, I investigate the issue of the contingency and inevitability of science. First, I point out valuable insights from the existing discussion about the issue. I then formulate a general framework, built on the notion of contrastive explanation and counterfactuals, that can be used to approach questions of contingency of science. I argue, with an example from the existing historiography of science, that this framework could be useful to historians of science. Finally, I argue that this framework shows the existing views on historical contingency and counterfactuals in a new light. The framework also shows the value of existing historiography in philosophical debates.

Sobre la respuesta de Carlos Moya al Argumento de la Suerte

On Carlos Moya's Reply to the Argument from Luck Resumen: Esta nota crítica se centra en el argumento de Carlos Moya (2017, 168-70) a favor de la conclusión de que el Argumento de la Suerte representa en realidad un problema mayor para los compatibilistas que para los libertaristas. La Sección 1 introduce brevemente el Argumento de la Suerte. La Sección 2 discute la distinción de Moya entre dos concepciones de deliberación práctica, y propone una manera alternativa a la de Moya de entender la crítica al libertarismo que se basa en la condición de que cualquier decisión libre debe tener una explicación contrastiva. Finalmente, la Sección 3 resume la respuesta libertarista de Moya al Argumento de la Suerte, y sugiere un modelo alternativo de determinismo que Moya podría considerar para completar su argumento. Palabras clave: libre albedrío, Argumento de la Suerte, libertarismo, compatibilismo, explicación contrastiva, determinismo. Abstract: This review focuses on Carlos Moya’s (2017, 168-70) argument for the conclusion that the Argument from Luck actually represents a greater problem for compatibilism than for libertarianism. Section 1 briefly introduces the Argument from Luck. Section 2 discusses Moya’s distinction between two conceptions of practical deliberation, and suggests a justification that Moya does not consider for the condition that any free decision must have a contrastive explanation. Finally, Section 3 summarizes Moya’s libertarian response to the Argument from Luck, and suggests an alternative model of determinism that Moya might consider to complete his argument. Keywords: free will, Argument from Luck, libertarianism compatibilism, contrastive explanation, determinism.