You are right, logic is subjective unless it is based on all the facts there are as opposed to all the facts there are available. If facts are missing then it is possible that the logical conclusion could be flawed. Hence, in the case of black holes, the probability that all the facts are not available leaves "holes" in the logic that must be filled by something. The holes get filled with "things that are _reasonable_" but those things, while reasonable, are not facts thus the conclusion must be flawed.
This is why science evolves. Because we come up with a hypothesis which is a "logical conclusion" based upon certain facts and a number of "reasonable" assumptions. Those assumptions are then tested until repeatable data can be generated. The repeatable data is then fed into the hypothesis and replaces some of the assumptions and we have a theory. The theory is then tested and bound with other facts until all the assumptions are replaced with facts. Then the logic can flow properly to it's conclusion and we have a truth. The truth is then constantly tested against emerging facts. If the facts change then the truth must also change.
Logic has to be infallible or it isn't logic. But logic is absolutely required to be based on fact. The moment the reasonable assumption is used the logic is flawed.
With regard to "beauty": This is something that logic cannot define since it is based on an emotion, (Billy _thinks_ Mary is attractive because Billy likes girls with red hair. Joe doesn't _think_ Mary is attractive because Joe likes girls with brown eyes and Mary has blue eyes). You could, I suppose, within the emotional landscape of any individual reach a logical conclusion as to whether any particular person would be attractive to them based on sufficient information regarding that persons likes and dislikes in the opposite sex, (or the same sex for that matter), but once you start trying to determine whether someone is attractive by using multiple other individuals likes and dislikes then logic has to fail because the "facts", (which are actually emotional responses), conflict with one another - because they aren't facts, they are the feelings of individuals.
