In the case of substances, Spinoza claims that every existing substance necessarily exists (Ip7d).
Even if every existing infinite mode necessarily exists, could there have been other infinite modes as well?
(Another plausible assumption: if something is not compossible with what necessarily exists, then its existence is not possible).
According to this reasoning, if God necessarily exists, and if the existence of a mode follows necessarily from the existence and nature of God, then that mode necessarily exists too.
There is, therefore, no basis whatsoever for the a priori claim that there necessarily exists an original, self-existing being that is an immaterial, intelligent being (i.e., God).
Therefore, the difference between process theism and traditional theism is not in whether something necessarily exists, but in the nature of the necessarily existent.
Furthermore, since every mediate infinite mode necessarily follows from something that necessarily exists (an immediate infinite mode), their existence is also absolutely necessary (Ip23).
Since mathematical statements such as 'The first prime number after 1,000,000 is 1,000,003' are necessary truths and can only be rendered true by the existence of a contingent being, Lowe concludes that there necessarily exists at least one contingent being.
Finally, Hume arguments against the notion of necessary existence have obvious relevance for Descartes's effort to prove that God necessarily exists by way of reasoning from our (innate) idea of God.
It concludes that God necessarily exists, because, if he did not, he would not be perfect.
A being that necessarily exists cannot coherently be thought not to exist.
