 His argument for the existence of substantial forms is thus effectively abductive: for some range of data or phenomena, Suárez contends, some explanation is required, and the only, or, more weakly, the best, explanation of these phenomena involves a commitment to substantial forms. So, his general argument schema is clear: (i) some phenomenon φ requires explanation; (ii) the only or best explanation of φ is the existence of substantial forms; hence, (iii) there are substantial forms. The argument thus assumes that the phenomena in question both obtain and are not primitive, that is, that we are confronted with some data for which some form of explanation is both wanting and available.