I have a bunch of questions and comments, but let me start with “Is RBW a retrocausal account?” You cite Geroch approvingly saying that nothing changes or moves in the blockworld. But that doesn’t seem right to me. Change/motion only make sense from the perspective of a world-line — the properties of one temporal part of the world-line are different from the properties of another temporal part. Of course the 4D world-line itself doesn’t move or change — that would be a conceptual confusion. But their contents change — in fact, that’s all that change means. But if you buy that, then why resist saying that RBW is retrocausal? Causation is something that appears from the perspective of a world-line. Of course, causation is a lot harder to characterize than change! But the fact that RBW explains a 4D situation “all at once” is no barrier in principle to characterizing the causation implicit in it. There may be other barriers to causal talk though, like the “unmediated” exchange of energy between emission and absorption, or the lack of counterfactual definiteness. But I’d be interested to hear what you think.
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