In his 1624 The Impiety of Deists, Atheists and Libertines of This Time... (dedicated to Cardinal Richelieu, by the way), Mersenne gives this fascinating little argument:
Nobody fails to acknowledge that if there is a supremely good being [un estre souverainement bon], it merits the name of God, since we don't mean anything by that name other than that which has all [the] sorts of perfections, and which lacks nothing. Now I will show that this supreme good exists. If it didn't exist, its privation would exist, which would be a supreme bad [mal], and consequently the supreme non-being, since the bad and the non-being are the same thing: but it doesn't in the least seem that the privation exists more than its actuality, which must necessary precede it. Thus one must confess that there is a supreme goodness, and then that there cannot be a supreme badness. So we have a supreme being, since we deny a supreme non-being, it being necessary that the one or the other exist....There is actually more than one argument here. There is an interesting and deeply metaphysical argument based on evil as the privation of a good. But there is also the kernel of a rather interesting and simple argument:
- It would be supremely bad if God doesn't exist.
- The world doesn't exemplify a supreme bad.
- So, God exists.