Conditionals and the Hierarchy of Causal Queries Niels Skovgaard-Olsen, Simon Stephan, and Michael R. Waldmann Department of Psychology, Cognitive and Decision Sciences, University of Göttingen Recent studies indicate that indicative conditionals like “If people wear masks, the spread of Covid-19 will be diminished” require a probabilistic dependency between their antecedents and consequents to be acceptable (Skovgaard-Olsen et al., 2016). But it is easy to make the slip from this claim to the thesis that indicative conditionals are acceptable only if this probabilistic dependency results from a causal relation between antecedent and consequent. According to Pearl (2009), understanding a causal relation involves multiple, hierarchically organized concep- tual dimensions: prediction, intervention, and counterfactual dependence. In a series of experi- ments, we test the hypothesis that these conceptual dimensions are differentially encoded in indicative and counterfactual conditionals. If this hypothesis holds, then there are limits as to how much of a causal relation is captured by indicative conditionals alone. Our results show that the acceptance of indicative and counterfactual conditionals can become dissociated. Furthermore, it is found that the acceptance of both is needed for accepting a causal relation between two co-occurring events. The implications that these findings have for the hypothesis above, and for recent debates at the intersection of the psychology of reasoning and causal judgment, are critically discussed. Our findings are consistent with viewing indicative condition- als as answering predictive queries requiring evidential relevance (even in the absence of direct causal relations). Counterfactual conditionals in contrast target causal relevance, specifically. Finally, we discuss the implications our results have for the yet unsolved question of how rea- soners succeed in constructing causal models from verbal descriptions. Keywords: causality, conditionals, counterfactual, reasons, relevance Supplemental materials: https://doi.org/10.1037/xge0001062.supp There is wide agreement that conditional statements of the type “if A, then C” play a central role in reasoning and argumentation (where A refers to the antecedent and C to the consequent). For instance, in 2019 much political discussion centered around the statement “If Trump is impeached, then it will affect the 2020 election. ” At the same time, conditionals pose many unsolved theoretical problems that have kept researchers busy, despite continuous, multidisciplinary efforts (Bennett, 2003; Kern-Isberner, 2001; Kratzer, 2012; Nicker- son, 2015; Oaksford & Chater, 2010b; Spohn, 2013). One of the reasons why conditionals are thought to be so central in our cognitive lives is because of their relationship with causal knowledge (Oaksford & Chater, 2010a). The lin- guistic encoding of knowledge about causal relations in condi- tionals plays a vital role for the cultural transfer of causal knowledge across generations. For causal knowledge about objects that are not in our immediate vicinity, we rely on cul- turally transferred causal knowledge. The same goes for objects that are governed by mechanisms, which we do not fully understand, like artifacts designed by engineers. In addi- tion, the acquisition of causal knowledge through observed covariances and interventions dealing with the objects that are in our direct vicinity is often guided by linguistically acquired causal schemes (Gopnik et al., 2004). Various authors have emphasized that probably most of our causal knowledge comes through this linguistic source (e.g., Pearl, 2009; Ch. 7). But according to Danks (2014; Ch. 4), it is also the one that is the least investigated empirically. The relationship between conditionals and causal relations has, however, been the focus of much theoretical discussion. The im- portance of this issue is highlighted by counterfactual approaches to causation coming from philosophy (Collins et al., 2004; Good- man, 1947; Lewis, 1973a), computer science (Pearl, 2009), and statistics (Morgan & Winship, 2018; VanderWeele, 2015). Recently, various authors in psychology and philosophy have also made a case for causal interpretations of indicative conditionals (e.g., Andreas & Günther, 2018; Oaksford & Chater, 2017; van Rooij & Schulz, 2019; Vandenburgh, 2020). In this article, we investigate whether indicative conditionals by themselves suffice to express causal relations or whether there are This article was published Online First December 9, 2021. We thank Dominik Glandorf, Louisa Reins, and Maike Holland-Letz for their help in coding responses and setting up experiments. We also thank audiences at talks at London Reasoning Workshop (2019), EuroCogSci (2019), and Regensburg University (2020) for valuable feedback. Correspondence concerning this article should be addressed to Niels Skovgaard-Olsen, Department of Psychology, Cognitive and Decision Sciences, University of Göttingen, Goßlerstraße 14, 37073 Göttingen, Germany. Email: niels.skovgaard-olsen@psych.uni-goettingen.de 2472 Journal of Experimental Psychology: General © 2021 American Psychological Association 2021, Vol. 150, No. 12, 2472–2505 ISSN: 0096-3445 https://doi.org/10.1037/xge0001062 This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.