If you care about “causal reasoning”, the other half of what’s supposed to make Newcomb confusing, then Joe’s problem is more like Kavka’s (so this post accidentally shows how Kavka and Newcomb are similar). But the distinction is instrumentally irrelevant: the point is that he can benefit from decision mechanisms that are evidential and time-invariant, and you don’t need “unreasonable certainties” or “paradoxes of causality” for this to come up.
There is no need for time-invariance. The most generic model (2 Joe nodes; 1 Kate note; 3 Nature nodes) of vanilla decision theory perfectly explains the situation you’re talking about—unless you postulate some causal loops.
And in Kavka’s problem there’s no paradox unless we assume causal loops (billionaire knows now if you’re going to decide to drink the toxin or not tomorrow), or leave the problem ambiguous (so can you change or mind or not?).
My pre-sponse to this is in footnote 2:
There is no need for time-invariance. The most generic model (2 Joe nodes; 1 Kate note; 3 Nature nodes) of vanilla decision theory perfectly explains the situation you’re talking about—unless you postulate some causal loops.
Is that not the simplicity you’re interested in?
And in Kavka’s problem there’s no paradox unless we assume causal loops (billionaire knows now if you’re going to decide to drink the toxin or not tomorrow), or leave the problem ambiguous (so can you change or mind or not?).
You’ll notice I didn’t once use the word “paradox” ;)