Prop. VII. Existence Belongs to the Nature of Substance
Spinoza demonstrates this by arguing substance must be the cause of itself, i.e. existence must belong to the nature of substance (by def. 1). In doing so, he references only the corollary of Prop. VI., which states that substance cannot be produced by anything else. From what I can tell, this does not preclude a substance not existing. I feel there is an assumed “if it exists” preceding Prop. VII., though I don’t doubt it may be possible how it is written is correct and can be arrived at following what’s written prior in Part I. Can anyone provide insight on how Spinoza arrived at the claim that substances must cause themselves rather than not exist at all?
Note: Spinoza makes another argument in the second scholium of Prop. VIII. for the essential existence of substance, but from what I can tell, this is similarly based upon the absurdity of substance being created and does not mention the case where substance doesn’t exist.