In any case, most of the relevant arguments are old hat. However, I did recently come across a new one to me, at least in this particular form, which I thought nicely done, in a post by Fr. Kimel, in which he quotes Kronan & Reitan's version of an argument by Thomas Talbott:
1. Anyone in a state of eternal blessedness possesses both perfect bliss and universal love for all persons.
2. Anyone who possesses universal love for all persons and who is aware that some persons are eternally damned cannot possess perfect bliss.
3. Therefore, anyone who is aware that some persons are eternally damned cannot possess eternal blessedness (1, 2).
4. If anyone is eternally damned, anyone who possesses eternal blessedness would be aware of this.
5. Thus, if anyone is eternally damned, then none possess eternal blessedness (3, 4).
6. God, out of benevolent love for His creatures, confers blessedness at least on those who earnestly repent and seek communion with Him.
7. Therefore, God does not eternally damn anyone (5, 6).
As Fr. Kimel notes, (2) is the most controversial premise, and, although he provides some argument to motivate it, it is in fact fatally wrong: while it may be possible to provide a reasonably workable argument from divine love to universalism, one cannot possibly do it by way of the bliss of heaven. The particular complete joy that is intrinsic to heaven itself (which is all that can be meant by perfect bliss in (1)) consists of possession of God as universal and consummate good by love and understanding, or to look at it in the opposite direction, being energized by God as universal good in both understanding and will. It follows immediately and directly from such a union, and therefore cannot be affected by anything else, however important in other ways. Indeed, since by nature it flows directly from God in that union, it is not in the power of the blessed not to have it, regardless of anything else that may happen to them. Now, one can argue (as Fr. Kimel does) that God would in fact seek to please the blessed in secondary ways that presuppose this complete joy -- and there is reason for thinking this at least sometimes true -- but this turns what at first sight looks like a rigorous argument into a rather weak, merely probabilistic and limited one: as (2) then becomes only probable and all-things-considered, the conclusion can be only probable and all-things-considered. It is at best a default that can be defeated by contrary reasons. Thus the argument against hell ironically founders on its conception of heavenly bliss.
None of this, of course, determines matters one way or another, since one's doctrine of the afterlife should certainly not be based on such tenuous considerations; it's just a matter of an interesting argument that has an interesting flaw.
