Abstract

It is often claimed that adultery can be morally permissible in cases where those engaged in adulterous behavior are part of an open marriage. Yet this only follows if the institution of open marriage itself can be justified. This problem has been generally overlooked, but it deserves attention, as it is far from evident that open marriage has sterling moral credentials. I argue that the most promising general justification of the institution of open marriage is not based on consequentialist or aretaic principles, but rather on the principle of respect for autonomy. Yet while this principle justifies the institution of open marriage in the most general sense, it does not justify every case of adultery involving an open marriage. Whether a given case of adultery is rendered morally permissible by the presence of an open marriage will depend on whether the open marriage in question satisfies several other moral desiderata.