Gracia Di Rienzo, Alejandro2026-04-172026-04-172026-01-21Di Rienzo, A. G. (2026). A Collapse Result in the Mereology of Properties. Ratio, 1-9. https://doi.org/10.1111/rati.70017https://hdl.handle.net/10347/46766I examine five principles about the metaphysics of properties, each of which has been defended in the literature: (1) the sum of properties is their corresponding conjunctive property, (2) the mereology of properties is classical, (3) properties are individuated by necessary co-instantiation, (4) sums of objects belonging to different categories do not belong to the category of any of their parts, and (5) there is at least a property necessarily instantiated by every individual. I prove that this package of views entails that there is exactly one property. Since this conclusion is highly implausible, I will discuss some ways of modifying the package in order to avoid it.eng© 2026 The Author(s). Ratio published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.Attribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/Existence monismMereologyMonismProperties11 Lógicajournal article10.1111/rati.700171467-9329open access