‘hypothesis,’ ‘premise,’ ‘acceptance,’ and ‘imagining’ (Alston, 1996, 2007; Bratman, 1992; Cohen, 1992; Engel, 2012; Frankish, 2004; Stalnaker, 1984). For my purposes here, I will talk in terms of ‘supposing,’ but any mental ontology distinguishing belief from some other belief-like state should be amenable to my suggested approach of counterpossibles. Thus, in addition to there being a ‘belief box’ and ‘desire box’ in their computational account of reasoning, there is a ‘possible world’ box. The possible world box only indirectly affects beliefs because all interactions between beliefs and suppositions are mediated through inference formation. One important inference mechanism is called ‘updater,’ which searches for inconsistencies and alters beliefs as circumstances change or novel beliefs are acquired. Most importantly for my purposes, updater ‘screens out’ beliefs that are inconsistent with those propositions currently in the possible world box. There are three crucial claims on Nichols and Stich’s account. First, the very same inference mechanism operates on suppositions and beliefs (p. 29). Second, suppositions and beliefs do not differ in the type of content (the two are of the “same logical form” p. 32). Third, suppositions and beliefs may combine in inferences (p. 32). Because Nichols and Stich’s aim is to defend their own account of hybrid folk psychology (combining theory-theory and simulation-theory), they spend little time considering the important implications for counterfactual reasoning. Stanovich (2011) applies Leslie’s and Nichols and Stich’s accounts to counterfactual reasoning (or what he calls ‘reflective thinking’). Stanovich (2011) claims that when we engage in novel counterfactual reasoning, subjects can represent a possible world in which the premises are true, and then search for a counter-example to the conclusion. While Stanovich’s account is theory-laden within a problematic dual-process framework (see Osman 2004; Keren and Schul 2009; Kruglanski & Gigerenzer, 2011; and Mugg 2013, forthcoming,), he is right in emphasizing the importance of cognitive decoupling in human reasoning.

- 4. Pretending that God exists (or does not exist)

Cognitive decoupling occurs when subjects extract information from a representation and perform computations on that extracted information. What is crucial to cognitive decoupling is the ‘screening out’ of information. I will say that beliefs are ‘screened out’ just in case they are kept separate from the reasoning process (i.e. they do not figure as premises in the argument and exert no causal influence over the reasoning process). Those beliefs that are allowed into the reasoning process, along with the suppositions, are ‘cognitively quarantined’ from the subject’s beliefs. Consider the following syllogism:

- 9. All whales are mammals.
- 10. All whales nurse their young.
- Therefore,
- 11. All mammals nurse their young.

I am sure you recognized that this syllogism is invalid, even though 9-11 are all true. How did you do so? One way is to construct an imagined state of affairs in which the premises are true and check whether the conclusion must be true in that state of affairs. In doing so, you must ‘screen out’ the belief that 11 is true. That is, you must ignore that 11 is true and keep the truth of 11 from interfering with the reasoning process whereby you judge whether 11 follows from 9