Abstract

Gordon P. Barnes has recently argued that presence by power is inadequate as an explanation of the way elements are present in complex bodies, and that it would be better to explain the elements’ presence by claiming that simpler substances—carbon atoms, for example—are actually and substantially present in living things. In order to address his arguments, this paper begins by briefly presenting St. Thomas’s understanding of presence by power, and then argues that Barnes’s proposal—that there is a multiplicity of substantial forms in one matter—is unsatisfactory. First, the paper explains why the scientific facts do not require a plurality of substantial forms. Second, it shows how Barnes’s theory does not adequately explain living things. Third, it argues against Barnes’s claim that St. Thomas’s explanation is insufficient because it denies "the universal causality of nature."