Okay, snark-hat off: "Arkay the Enemy" doesn't really posit an a priori Divine Arkay, who would've contributed to the world's creation at the Convention, alongside a johnny-come-later mortal Arkay, who seems to experience a Tiber-like apotheosis during his lifetime.
Meaning it doesn't really address the paradox. Which is why the assignment is worth 8,000 freakin points.
Hey, if Vivec can do it, why not Arkay?
Lots of stuff seems to suggest the mutability of time--Dragon Breaks and such. In addition, though I can't explain it well, a lot of this stuff just plain FEELS like time-travel to me. Like "slingshot the Paravant into era-streams" sounds a LOT like time-travel, Star Trek style. The Void is Outer-Space, though the fantasy nature of it makes it wierd. When you travel through the void, you leave the realm of linear time, and into the realm of possibilities (hence, they call it a "dream-sleave jump" referring to the fact that a dream-sleave can transmit ideas that don't yet exist, or whatever).
Thus, when you slingshot into an era-stream... you're time-traveling.
All you have to do to become a god is to be around for the creation. All you have to do to be around for the creation is time-travel back to that "time". Thus, both Arkay and Vivec, though they were mortal men during our own timeline, ALSO are gods from the state of things before linear time began. So which came first? In terms of time, the gods came first. In terms of what I'll call life-flow, the men came first... but the world in which they existed was CREATED by the gods...
Only madness can result from such a line of inquiry.