If there is something non-reducible to anything else, self-existent, unsusceptible to further explanation, then in what sense might it befundamental, and in what sense might it beunified? In my response to Kerry McKenzie and Peter Adamson, I try to clarify the idea of “foundation” that these arguments claim to show, by first contrasting two conceptions of fundamentality (a concrete complete bottom level from which the world isbuilt up –the kind people often have in mind, and an ultimate modal determination thatexplainsthings), (...) and then discussing McKenzie’s main worry that what is modally irreducible does not necessarily qualify as fundamental, and Adamson’s worry that the bottom-level entities need not be numerically single. (shrink)