 Cartesians and Thomists alike believed on scriptural grounds that there were actual cases of separated souls, namely, the angels, fallen and unfallen, so the possibility that the human soul might itself be subsistent was simply the possibility that it might sufficiently resemble an already accepted ontological group: despite the problems that substance dualism raises, a number of which presented themselves clearly to Boyle, there was no general problem concerning incorporeal entities, and there were, Boyle felt, strong arguments for the incorporeality of the human soul.