Defending the Grim Reaper

I've received some criticisms lately directed toward my version of the Grim Reaper argument for causal finitism. The criticism comes from Alex Malpass and Joe Schmid, My argument depends heavily on a version of David Lewis's Patchwork Principle.

Malpass and Schmid argue (on Schmid's Majesty of Reason web site) that theists must reject the Patchwork Principle, since it seems to entail the existence of a world in which nothing occurs except pointless suffering. It might be supposed that theists hold such a world to be metaphysically impossible. (I'm not so sure--a spacetime world could be filled with suffering, while that suffering might find its point and purpose in a separate spacetime continuum, as in a multiverse. However, I'll concede the point here for the sake of argument.)

Malpass and Schmid are right to point out that the Patchwork Principle needs to be qualified. Here is a plausible version:

Patchwork Principle
If (a) there is a world w1 containing a scenario S, (b) a world w2 containing enough non-overlapping regions of spacetime to accommodate an infinite regress of S-scenarios, (c) an infinite regress of S-scenarios would not violate the principle of causality (i.e., it wouldn’t involve any absolutely uncaused events), and (d) there is no necessary being with necessarily both the causal power and the inclination to prevent the existence of infinite regresses of S-scenarios, then: there is a world w3 in which there is an infinite regress of S-scenarios.

This doesn’t “beg the question” because including clause (d) does not entail that there is any necessary being at all. In fact, it presumes that, if there were such a being, it wouldn’t be necessarily disposed to prevent infinite regresses,

The Grim Reaper does not involve any violations of causality, so condition (c) is irrelevant. So, the correct conclusion should be the disjunction: either (i) infinite causal regresses are impossible (because they cannot be fit into a possible spacetime structure), or (ii) there is a necessary being with the power and inclination to prevent infinite causal regresses.

So, neither disjunct will be acceptable to the atheist,