Example: You are a black slave in 1800, how would you understanding of philosophy and your assertion of this philosophy, convince them that you are not property.
Example: You are a Jew in a Nazi death camp, how would you application of moral and ethical philosophy, make them open the gates and free you.
Example: What would you tell a 10 year old Afghan child, who has watched his entire family destroyed by a tax paid war machine. Would you quote Sun Tzu "The supreme art of war is to subdue the enemy without fighting," or tell him "Only the dead have seen an end to war?"
The question is questioning the merit of philosophy itself, in other words its easy to have a stanch on a certain philosophy when you are detached from the situation, but when the issue of morality and ethics is pointing at gun at you ... well, what use is it.
So moral and ethical philosophies are only as relevant as the situation. So in other words, moral and ethics "only really apply ... when they happen to apply."
Gravity exists and is relevant, but one can always fall from a building, and gravity won't give a damn. Ethics (or a given piece of) could be used to explain why Nazis shouldn't kill the Jew, but the Nazis wouldn't care for it. On the other hand, I try to evaluate things in that light: if we both had a disagreement of some kind, and you offered some ethical and logical reasons, I would be all "Ok!" -- but that's me. I think it's clear that ethics, at least to the masses, is somewhat like a communication protocol, enabling the community to strengthen their relations and upgrade their life quality and efficiency in whatever. The Jew could use a perfect logical argument, but the Nazi wouldn't care. Nothing wrong with ethics. I can say 2 + 2 = 5, that won't change maths.
Well, Hume tells us all philosophy comes from sense experience and even an isolated person with little education would think why is there something rather than nothing?
To be honest, reason and logic are always inferior to brute force (that is a bluntly stated honest fact). It is emotions, not reason, that are the true moving forces in this world. It is emotions that enabled national socialist death camps, it is emotions (like fear, loathing and arrogance--and partly greed and egoism) that are the main causes of conflicts in the Middle-East. But regardless of the apparent superiority of emotions over reason, this does not make reason and logic somehow irrelevant.