  Despite worries that one might have about the validity of Spinoza’s argument, the doctrine has at least some claim to plausibility as an account of the nature of particular things. The Ethics stands badly in need of some account of what finite modes are, after all, and IIIp4 provides at least one interesting way of distinguishing genuine objects from mere constructs: if the thing in question destroys itself it is not a genuine object. Thus, by IIIp4, a thing that destroys itself—one might think a lit candle or a time bomb such a thing—is not a genuine object but a thing which does not destroy itself is. To the extent that IIIp4 makes most of the things we intuitively consider genuine objects genuine objects, it captures ordinary views. To the extent that it rules out some clear class of things that we intuitively consider genuine objects (lit candles and time bombs), it represents a controversial philosophical thesis. The plausibility of the doctrine depends on whether we find that there really is reason to find basic metaphysical differences in kind between “things” which tend to destroy themselves and things which do not.  One strategy for defending the plausibility of IIIp4 may be to investigate what Spinoza means there by an “external cause.” Spinoza’s various claims about essences, properties, and accidents suggest that at least some of the cases of destruction that we might consider self-destruction are, for Spinoza, destruction by external causes (Garrett, 2002, pursues this strategy), a suggestion that is supported by Spinoza’s account of suicide later in the Ethics at IVp20s.   The class of things which tend to destroy themselves may be different from, and narrower than, one might think it is on a first reading of IIIp4.