What's also ironic is that luke, who wrote the post you're responding to, has recently argued at some length that it's important to acknowledge the relationships between LW and mainstream philosophy and in particular the places where LW/EY owe debts to mainstream philosophy.
A reasonable man might infer from this that he's not entirely blinded by groupthink on this particular subject.
Of course, that doesn't mean all the rest of us aren't... though we sure do seem to have a lot of internal disagreement for a bona fide cult.
4wnoise
All thinking all-by-himself? No. Great chunks, while being immersed in the culture that resulted from that thinking, sure.
For direct influences, Eliezer is quite willing to cite e.g. Feynmann, Dennet, Pearl and Drescher.
I don't see the connection you see to Nietzsche in particular, merely a bunch of things that are tangential at best. Would you be willing to spell out which bits of his writings are like which bits of Nietzsche? I would strongly guess that anything you identify is not particularly unique to Nietzsche, and similar points had been made both before and after him, and any that did have no antecedents before him leaked out into the broader culture.
It depends on what you mean by this being "original thinking". Eliezer almost certainly isn't directly mining 19th century German philosophers for ideas. I doubt he has read much if any Nietzsche and would thus not be able to directly copy Nietzsche. Nonetheless, some ideas of Nietzsche have made their way into modern world view. Ideas are generally dense and interconnected. Starting at one idea of a philosopher and thinking about the implications are going to produce similar new ideas to others the philosopher had.
Yes, one should keep clear that one's ideas that apparently arise from within are crucially dependent on previous experiences and culture. But that doesn't extend to a requirement to track down and cite previous articulators of similar ideas. Once an idea is encountered indirectly, it's free game to build upon. It's long been recognized that certain ideas arise multiple times apparently independently when the prerequisites take root in a given culture. Newton and Liebniz independently invented calculus, with no direct connection. I'm sure neither could cite any direct influence from prior mathematicians that would directly lead to calculus. But there was still enough commonality in mathematical culture that they developed it at roughly the same time.