Richard wrote: "I propose that causal chains that go on forever or indefinitely are important; causal chains that peter out are unimportant."
This makes some sense if there are causal chains of infinite length, but on what grounds do you know that there are? It's a bit like saying "Humans' interests are of no importance next to those of the gods" before you've got some evidence for the existence of the gods.
While my actions now might be able to produce, or alter, a causal chain of infinite length, their influence on that chain is likely to decay over time, probably exponentially. So when deciding what to do now, shouldn't I be applying some sort of discount even if I think all future times are equally important? If so, then it's far from clear that only infinite chains matter – even if there are any.