Late coming into this discussion: I was on vacation (in Mexico: no symptoms yet!)
I'm clinging to the belief that the numbers were 'created' in the lottery: assuming the lottery wasn't a fix, it's a random draw, so there's no opportunity for the past to influence it.
My original theory went like this:
- The numbers come up in the lottery
- Hurley wins the lottery
- Hurley has some bad luck: blames the numbers (backed up by various other people affected by island history)
- Plane crash, they find the hatch, Hurley's superstision about the numbers is reinforced
- Hurley goes back to the 70s, still obsessed with the numbers
- Hurley somehow influences the way the serial number etc. were selected in the first place
- Fast forward to the 90s; younger Hurley hears about the numbers from asylum guy, completing the loop
Note: not a falsidical paradox. It would only be a paradox of that kind if somehow the past became inconsistent with the future.
(Edited to add "falsidical" - it *is* a predestination paradox of sorts - but hey, that's a mainstay of literature)
Some Like It Hoth broke that theory somewhat - the hatch has its serial number, and we didn't see Hurley influence the choice of number.
However, other people exposed to the numbers also went back in time. Perhaps one of them (knowlingly?) assigned the numbers. Faraday? Someone we don't know went back? Someone we've never met?