@ballin
But if you take that line of reasoning, doesn't it lead to concluding there are no absolute moral truths at all? After all, if what is right to you comes down to your subjective opinion, wouldn't that hold for anyone? Including people like Hitler? So, for any moral truth that might be proposed, all you'd need would be one person who disagreed for a contradiction.
And here's my problem with that conclusion. The statement "There are no absolute moral truths" is either false... or an absolute moral truth.
I agree that there are no absolute moral truths.
I also don't think that statement in itself is a moral truth, since moral truths are prescriptive (tell you what you SHOULD do) whereas that statement does not tell you what you should do.
But even if you considered it to be such, I would change my position to "there are no absolute moral truths besides this statement" or whatever else.
Note also that I don't believe the statement "there are no absolute moral truths" is PROVEN or anything, it's just the default position until someone can prove that there are absolute moral truths (which I don't think is possible). It's similar to how the default position is "there are no Vulcans" - until someone shows me a Vulcan I will believe this statement.
Now, while I don't think there are absolute moral truths, I think that there are moral beliefs that most people agree with, and I think there is a generally correct morality that can be formed on the basis of a few axiom statements.
A1 (Axiom of equality): Humans have equal moral weight.
A2 (Axiom of difference): Humans have different moral preferences
From these two axioms, I can deduce that humans have different preferences, but at the moment each of these sets of preferences is equally good.
If the preferences never come in conflict, there is no problem. However, when there is a conflict of preferences, we have to look back to A1 to see that neither person MUST be right. Since they have equal moral weight, it would be wrong for one person to impose his moral preferences on another.
So whoever is imposing on another is in the wrong. This leads me to the Non-Aggression Principle:
NAP: It is wrong for a human to initiate force against another human (or his possessions).
Violating NAP is violating A1, the concession that your preferences are no better than anyone else's.
NAP is the main principle behind my morality. It says that violence, theft, and many other "obvious" things are wrong, yet it allows for people to make their own choices so long as they don't harm anyone else.
Now, this was just a super brief explanation and there are a whole bunch of other subjects to go into (like how do we determine who is initiating force, the role of property, and what is justified when someone breaks the rules, etc)