Mr. Epistemology has now hit his morning golf balls and will make one more attempt at clarification ...
On another thread, Greg Doudna took me to task for ridiculing his elaborate Walker scenario. I admit, it makes no sense to me if Walker's only purpose was to stage an assassination attempt to enhance his reputation. But Greg's scenario is like John Orr's: it's internally consistent and accounts for the entire event. You can take it or leave it and even say "that makes no sense" when what you really mean is "that makes no sense to me." You can't say THAT MAKES NO SENSE AT ALL, because it does hang together with internal consistency and logic.
One trap we shouldn't fall into is thinking that whatever we believe (e.g., the LN narrative) is the "default rational" position and any other position is either ipso facto irrational or so "extraordinary" that it requires "extraordinary" evidence. Atheists do this all the time on religion forums, and I think we see it here from some LN zealots. Greg's Walker theory is not irrational and is "extraordinary" (to me) only in the sense that it is wildly different from the conventional explanation and seems fantastically, unnecessarily elaborate. But it just requires evidence, not extraordinary evidence, and you can take it or leave it. I wasn't clear about that on the other thread, more or less suggesting you were insane if you believed it.
Unlike Greg's Walker scenario, which as I said accounts for the entire event, the supposed alteration of the Z film is not a stand-alone issue. If the issue were simply "Was the Z film altered?" then Kevin's point that the silliness is not self-evident would be true. There is at least a body of supposed evidence and expert opinion that might cause an entirely rational person to say, in a vacuum, "By God, I think it was altered."
But the supposed alteration of the Z film is not a stand-alone issue. It is part and parcel of some theory as to what took place with the JFKA. It has to make sense within that context. You have to be able to articulate an internally consistent and reasonably logical theory of the JFKA in which the need to alter the Z film and the supposed alteration of it MAKES SENSE. Your theory doesn't have to convince me, but it has to MAKE SENSE. In philosophical terms, it has to be "epistemologically justified" even it happens to be 100% untrue. I can't think of any such theory and haven't heard one. In fact, to me it seems ridiculous. But since hope springs eternal, I did issue my challenge.
This is why CTers play the endless game of "What about THIS?" and "What about THAT?" and "What about THAT over there?" They want every issue to be examined in a vacuum. "Z film alteration = conspiracy." If they can keep the focus on the supposed Z film alteration as though it were a stand-alone issue, they can sound sorta-kinda persuasive. When you say, "Super! So what was the conspiracy and how does the necessity to alter the Z film fit into it? How would that have worked, from the time they were planning the JFKA and considering the possibility of cameras in Dealey Plaza to Abe doing his filming to the events immediately thereafter to the alteration itself? How would it have worked and what sense would it have made?" - well, then, they have no answer and shift the focus to "And what about THAT over there?"