According to the version of modal fictionalism developed by Gideon Rosen, we should regard talk of possible worlds and the like as “an innocent façon de parler, involving no commitment to worlds of any sort”. The fictionalist’s interpretation of modal talk can be stated as follows:

(F) A iff According to Genuine Realism, A*

(Where ‘A’ is any sentence, ‘A*’ is its translation into the language of counterpart theory and ‘Genuine Realism‘ names a fiction based broadly on Lewis’s version of realism.

A common objection to modal fictionalism is that the account is, in some sense or other, hopelessly artificial. This isn’t really a single objection, but a cluster of related worries. In Being Known, Christopher Peacocke raises one version of the worry:

“The charge of fetishism lodged against the modal fictionalist is that there is no saying what is so special about the theory of possible worlds that is mentioned in the schema asserted by the modal fictionalist. Since the fictionalist does not take [Genuine Realism] to be true, why should we be peculiarly interested in what follows from it, rather than some other theory?”

The charge is that the fictionalist has an unreasonable fetish in the sense that she has no good reason to choose Genuine Realism as her fiction, as opposed to choosing a different fiction.

Of course, there are various constraints that the fictionalist can appeal to in order to provide non-arbitrary reasons as to why certain fictions are inadequate. For instance, the fictionalist does not think – assuming that she does not buy into paraconsistent logic – that an inconsistent fiction of possible worlds should be used. Rather, the challenge for the fictionalist is to provide some non-arbitrary reason for holding that Genuine Realism has some sort of authority that the other fictions lack.

Rosen suggests that Genuine Realism might gain its authority in virtue of “being an explicit formulation of our own imaginative habits”. His thought appears to be that if the fictionalist can establish that Genuine Realism is the best way to systematise our imaginative habits, then the fictionalist will have established that Genuine Realism important advantage over its rivals, which the fictionalist can exploit in order to give it its authority. As Rosen notes, this strategy would seem to make fictionalism a conceptualist account of modality, whereby the source of modal distinctions in us, in our capacity to imagine or conceive alternatives to the actual state of things. And though Rosen admits that conceptualist accounts have their problems, he states that his intention is merely to offer a “potentially fruitful” approach for the fictionalist to take in response to the charge of fetishism. However, it seems to me that the real motivation behind this kind of strategy is largely independent from any kind of conceptualist theory of modality. For our prior modal opinions are formed largely on the basis of our imaginative capacities so, rather than framing the point in terms of our imaginative habits, a less loaded suggestion might be that Genuine Realism gains its authority from being the fiction that is the most conservative over our prior modal opinions. In this setting, Rosen’s suggestion is that the fictionalist can argue that Genuine Realism is the authoritative fiction on the grounds that her interpretation of modal talk, based as it is on Genuine Realism, is extensionally accurate. And there is something to this suggestion. For let No Blue Swans be a fiction such that, according to it, there is no world containing a blue swan. An interpretation of modal talk in terms of the content of No Blue Swans would therefore be inaccurate by the fictionalist’s lights. And it seems plausible that the inaccuracy of this interpretation provides a good reason to prefer Genuine Realism to this rival fiction. By extension, the fictionalist has good reason to prefer Genuine Realism to No Talking Donkeys, No Flaming Zombies and other such fictions.

However, even if the strategy provides the fictionalist with good reason to prefer Genuine Realism to No Blue Swans and the like, the fictionalist has not yet given us any reason to prefer Genuine Realism over any other fiction. But suppose that there is a fiction of possible worlds such that an interpretation of modal talk in terms of that fiction is extensionally equivalent to the fictionalist’s interpretation in terms of Genuine Realism. If any such fiction exists, then the fictionalist cannot appeal to prior modal opinion – or to our imaginative habits – in order to give us reason to think that Genuine Realism has authority.

This shows that the fictionalist probably cannot appeal to considerations of extensional accuracy in order to justify her use of Genuine Realism over rival, extensionally equivalent fictions. For instance, there may be no reason to prefer a fiction based on Lewis’s own theory to a fiction based on Kris McDaniel’s version of Lewisian realism. The worst case scenario: there are a range of fictions, including, but not exhausted by, Genuine Realism such that there are no criteria available to the fictionalist which can be used to justify using Genuine Realism over the other fictions in the range. In this setting, the charge of fetishism seems to stick and the fictionalist’s account certainly looks artificial.

Is this game over? I don’t think so. For the crucial question is whether the fictionalist should be worried by this result. Certainly, one might think that some departure from the letter of Rosen’s fictionalism is required, but the spirit of the account can be retained. For the fictionalist might move from her original schema (F) to the following schema (F!):

(F!) A iff According to every fiction in the range, A*

The proposed schema is, in a sense, supervaluationist formulation of modal fictionalism. Rather that singling out a single fiction in the way that Rosen singles out Genuine Realism, the supervaluational fictionalist picks out a range of fictions and formulates her account in terms of what is true according to every fiction in that range. One can even see Rosen’s view as a limiting case where Genuine Realism exhausts the range of fictions. But even if it doesn’t, the charge of fetishism is avoided. The supervaluational fictionalist grants to Peacocke that there is no saying what is special about Genuine Realism in the sense that she grants that there is no saying why this fiction is more special than the other fictions in the range. As we have seen, however, the fictionalist does have principled reasons for thinking that there is something special about each fiction in the range. For example, each fiction in the range will be extensionally accurate and each will be an equally good formulation of our imaginative habits. But the supervaluational fictionalist realizes that it would be arbitrary to give any one theory in the range a special status and so refuses to do so. She avoids fetishizing any one fiction in the range by giving equal weight to each.
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