Can we trust our Moral Intuitions?

[The Grand Nudger]

But before you can justify such a question about morality you must assume there is a right answer and therefore an objective morality that would be independent of what any sentient creature thought. And this is something that has never been demonstrated. I tend to agree that morality is subjective and dependent on the existence of sentient beings. What would morality even mean in a lifeless universe?

In an objectivist view, the same thing it does in a universe bursting with life in principle.  Things don't have to be alive for us to feel as though defacing them is an issue of moral import, though we do tend to limit moral responsibility to those agents we deem competent, all of which, so far as we know...are alive.  

Conceptually, defacing a mountain isn't not-bad because it's just lifeless rock, and we might hold a person accountable where we don't hold a flash flood..though we may also believe people to have been negligent if some preventable natural disaster effects the same outcome.

That we are here to apprehend all of this is a given - but, again in an objectivist view, even without any witness, nothing about an act itself changes.  This is what's meant by objective morality.  That the bad making properties of x are properties of x...rather than properties of the observer y.  Saying that people apprehend good and bad and sentient creatures must be present to apprehend at all - full stop, is not equivalent to saying that the bad of x is due to those creatures' y(s) apprehensions.

Or, tldr version..it's not because I saw it that curbstomping an infant is bad, or anything about me at all. Moore would contend....in the same context, however, that any competent moral agent y who did see an infant curbstomped would notice the bad of that x. This is moral intuition, as described. What sorts of things do you reference when you want to assert that a given x is bad? Your personal opinions, your taste or appetite for x? Is there anything that you think is so bad..rather than explain it to a person questioning or skeptical, you'd just say "let's take a walk, I'll show you, and you tell me what you think"?