RJ 17 said:
Look, the reason being able to see the Ring is so important because you're trying to argue that Sauron "can see everything" when he can't even see the very object he's specifically looking for when he's looking right at it.
But I really didn't want to get into this argument in the first place, so I'll let Zhukov take over if he so desires. But as an olive-branch, let me offer you this:
I get why the Eagles weren't used, because as cliche as this saying has become it holds perfectly true for the story of The Lord of the Rings: "It's about the journey, not the quest." The story isn't about Frodo throwing a ring into a volcano, it's about what he had to do to get there. What the other's had to do to help him in indirect ways. The battles that are fought, the heroes that are born, all that good stuff. That is the irrefutable reason that the Eagles aren't used, and we got a damn good story out of it. The over-all point is that LotR is not the first story to have a major plot-hole in it, nor was it the last. I still enjoy the story despite this - as I and many others see it - glaring plot-hole.
It's just a bit frustrating, to me at least, that you do see this as a glaring plot-hole. Because it really isn't. Even if Sauron can't spot the Ring, he spots the Hobbits. Hobbits are smaller and less of a threat than Eagles, especially since they're disguised as Orcs and Sauron assumes, at that point in time, that the Hobbits are being used as scouts and spies by Aragorn (the man he presumes has the Ring). Ergo, we can probably assume that given Sauron's ability to spot Hobbits, he would have no trouble spotting the much larger and much more threatening Eagles. Whether or not he can detect that those Eagles are carrying the Ring is, at that point, irrelevant. He will take that as an attack by the very beings that were able to permanently scar Morgoth himself. And once spotted, Sauron has a myriad of ways to dispose of them. He has weather control, flying monsters and animals, and the force of his stare alone could send them toppling to their deaths.
I'm not arguing that Sauron is omnipotent, that this attack would be doomed to fail. I'd say its odds of success are low, but not impossible. When weighing up the odds, the Council decided that the greatest odds of success lay in a small force sneaking past Sauron's gaze, and that's what they went with (and it worked). I don't call the decision not to mount a risky aerial assault a plot hole, and so I don't even have to go through the bother of looking past it to enjoy the awesome story that is Lord of the Rings. There doesn't have to be an "enjoy the story despite this", it's as simple as "enjoy the story". This particular plot hole is, and has always been, a fallacy.