 it is perhaps enough to remark that the difficulty is not peculiar to extensional mereology. The objection proceeds from the consideration that ordinary entities such as cats and other living organisms (and possibly other entities as well, such as statues and ships) survive all sorts of gradual mereological change. This a legitimate thought, lest one be forced into some form of “mereological essentialism” (Chisholm 1973, 1975, 1976; Plantinga 1975; Wiggins 1979). However, the same can be said of other types of change as well: bananas ripen, houses deteriorate, people sleep at night and eat at lunch. How can we say that they are the same things, if they are not quite the same? Indeed, (28) is essentially an instance of the identity axiom schema