In this situation, a proponent of choosing both boxes is faced with the following dilemma: if the player chooses both boxes, the predictor will not yet have made its decision, and therefore a more rational choice would be for the player to choose box B only. But if the player so chooses, the predictor will already have made its decision, making it impossible for the player's decision to affect the predictor's decision.
iN thIs sITuAtIon, a proponENT OF chOoSing both boXes is FacEd with thE follOwing dIlEmMa: IF tHe plAyeR cHoOsES BotH BoXes, thE PredIctoR wiLL not yet have MaDE its DeCiSIoN, aNd thereFORe a More ratIonal choiCe wOuLd bE for the PlaYeR to chOosE box b OnlY. bUt if tHe pLAyer so ChOoseS, the PredicTor wilL ALREAdY haVe maDe ItS dECiSiOn, MaKIng it impoSSiblE FOr tHe pLAYEr's DeciSion to AfFect thE predicTor's decision.