First, philosophy does not manage, ultimately, to answer these things. As an example, suppose that I think that 'X' is moral and you think that 'X' is immoral. Is there any way to resolve the dispute? I could give specific examples, but I don't want to get caught up in the rhetoric of controversial subjects. Let's simply address the issue of whether it is possible, even in principle, to resolve moral disputes.<quoted text>
Why do you use the word "reliable" in this way? Let's go into philosophy of morality for a round of discussion.
Is it wrong to kill a child? Is it wrong to rape a woman? Is it wrong to steal? Is it wrong to cheat at a game or contest? Is it wrong to lie?
In the sciences, there is such a way to resolve disputes: find an experiment that will go different ways depending on whether you or I are correct and then *do* the experiment and see. Now, in practice, it might be difficult to find such an experiment, or to design it and perform it, but that is ultimately how disputes in science are resolved. Any question that cannot be resolved by an experiment, even in principle, is deemed to be meaningless or irrelevant.
In mathematics, there is also a way to resolve disputes. One side or the other provides a proof from the accepted axioms and the other gets to challenge any logic in the proof. If all challenges fail, then the proof is accepted.
Now, the *lack* of a dispute resolution protocol for morality strongly suggests that moral questions are not questions of knowledge. Instead, they are questions of opinion and/or popularity. If most people agree that 'X' is wrong, then 'X' is wrong. Instead of logic, most people use rhetorical devices and appeals to emotions to argue for their moral positions. This also is revealing concerning their truth value.
What I have found is that moral questions tend to boil down fundamental assumptions about freedom, responsibility, tradition, etc. They ultimately rely on the question of what kind of society we want to live in and what rules should apply to who. Over time, we have decided that rules should be applied universally (although this is rare in practice) and that each person should be given equal value (again, purely theoretically).