Suppose there were a Mathesis Universalis- i.e. an 'eidetic science of the object in general' (Husserl)- which, if propounded, everybody would agree fits the bill, and suppose this yields an evidentiary decision theory all Muth rational people would adhere to, what happens to counterfactual conditionals? In particular, what would Stalnaker's closest possible world to our own look like?
Let's take a Josephine's Kingdom type situation populated by Muth rational, Mathesis Universalis possessing, Vandana Shivas married to men who may or may not be evil, G.M food advocating, gang rapists of the genomes of innocent Saree wearing plants. No Vandana Shiva knows if her own husband is a gang rapist- there is no objective test for the condition since such creatures have no real existence but are a figment of Vandana Shiva discourse- but does know which of the other Vandana Shivas is married to a gang rapist because Vandanaji's PhD in Philosophy dealt with Quantum non-locality, Corporate Globalization, and the gang-rape of plant genomes this inevitably gives rise to .
However, since Vandana Shivas never listen to each other, or themselves, there is no way for a particular Vandanaji to be told her husband is or is not a gang rapist. Josephine, the Queen of the Kingdom, announces that gang-rapist husbands exist and orders all Vandanas to shoot their gang rapist husband at midnight of the same day they realize he must be outraging the modesty of the genomes of innocent plants. All Vandanas can hear or otherwise get information about who got shot.
Suppose there is only one gang rapist. Then there is one Vandana who knows all other men, save her hubby, are innocent, so she shoots him. Suppose there are two gang rapists. Then there are two women who think there is only one rapist. So they expect one shooting and when it does not happen, next night shoot their own husband. Suppose there are three gang rapists. Then there are three women who think there are only two rapists and know, because no one gets shot on day one or two, that their husband is guilty and shoot him on the third day.
Clearly, by induction, all gang rapists will get shot within x number of days- where x is the number of gang rapists.
Now let us mix things up by changing Josephine's directive to her Vandana subjects so that it reads - 'kill your husband iff he is a gang rapist of the plant genome in the Stalnaker closest possible world, or even the Lewis 'sphere of very close possible worlds'.
The problem for us here is that though such gang rapists only exist in Vandana Siva theory and (since all Sivas are Muth rational) so the number of such gang rapists is knowable, still Josephine's directive is not well specified. Is she saying- kill x if in a closely possible world he is a y- or is the gravamen of her order rather- if you are married to a y in the closest possible world, then kill the x you are married to in this?' In any case, is the closest possible world one identical in every respect except x is a y?
However, we are assuming that 'an eidetic science of the object in general' actually exists and is possessed by relevant Muth Rational agents. To say that the problem we encounter makes Josephine's directive dangerously ambiguous is to say that we can't conceive of a Mathesis Universalis compossible with our ordinary, or even Stalnaker specified, notions of intentionality and meaning. In other words, on one horn of the dilemma, eidetics is empty, on the other, intentionality is vacuous.