Is this intended as a personal attack or is there some other intention? This looks a bit like a series of boo lights apparently directed at me.

If I say I am confused, then I mean that I am confused.

What do you mean by "axiomatic assumptions of rational honesty"

I mean that I take it as an axiomatic principle that my conversants are honest and rational actors until such time as they demonstrate otherwise.

and how do you think what I have said is "internally" and "externally" inconsistent?

Internally inconsistent means that the statements contradict themselves. Externally inconsistent means the statements contradict the known facts outside the statements.

You and I have the same datasets available for this conversation. You claim that you have read Stipp's book and yet you still claim that there has been strong historical interest in antiagapics research within the mainstream community. Stipps book contradicts this claim.

This is an internally inconsistent claim. You then go on to make many externally inconsistent statements such as claiming that the question of whether humans operate on calorie-restricted metabolism is yet at question, or the claim that geriontology's studies of human longevity have sufficiently little to do with determining the maximal human lifespan that you are confused by why I would even bring it up.

These are all points that tend to lead towards the conclusion of dishonesty or irrationality on your part. I'm not trying to claim that I have made that conclusion, just that I am confused as to how it is possible that you are not being dishonest or irrational -- because I am continuing to operate on the axiomatic assumption that you are in fact honest and rational.

So, if there's something common in say the Western diet that reduces the effects of reservatrol or some similar compound, we might not even notice until we notice that the anti-aging compound is having much less of an effect than anticipated. And then you'd need to go and test those compounds. That sort of problem falls easily in the "remotely plausible" line of failures or in the "conceivable" world-lines you mentioned earlier.

No, it doesn't. No pharmaceutical will receive widespread adoption until such time as it has been rigorously studied for how it behaves and what its contraindications and/or interactions are. That includes diets. These are all things that are normally controlled for. There is nothing "remotely plausible" about your proposed scenario: the entire pharmaceutical approvals process would have to be abandoned for it to occur.

That's fine if your claim is "this is likely to work" or even "this is very likely to work." But you've claimed that there's no conceivable world-line where this isn't working in fifty years and there hasn't been societal collapse or something similar preventing the research.

There isn't any one single this, is my point. Science and medicine are converging significantly. There is now a concerted effort to solving this particular problem. The scale of extension is, compared to what is conceivable possible, very minor.

My claim is that there are so many things which can be stated to be very likely to work that the idea of all of them failing would require a total overhaul of several fundamental models that I hold to be true based on their history of providing valid conclusions.

I don't believe that the problem we have here is one of inferential distance. I am very familiar with what that problem looks like. What we have instead is the fact that somehow we are both operating with the same sets of available data yet reaching different conclusions.

Aumann's Agreement Theorem has something to say about that -- and with that I suppose I am now verging into the territory of claiming dishonesty/irrationality on your part. (I admit it could conceivable be on my part as well, but I have as yet no indications towards inconsistency in any of my statements aside from the assumption of rational-honesty on your part.)