I wanted to say that a totaly isolated person can still live by a certain moral system.
How can a totally isolated individual's "moral system" be different from anything else that he does? After all, if he is the sole judge of his actions, then what is good for him is a fortiori
"good." In effect, "doing good deeds" and "eating good foods" would be morally equivalent statements.
This can give him a sense of goodness, as well as internal pleasure, consistency and sense of 'oneness' with his God, or environment he feels entangled with.
To the extent that living morally leads to spiritual contentment, this is a matter for psychologists, not philosophers.
This is not just functional justification of a certain rule system, this considers qualia, and is thus concerned also with 'goodness'.
To the extent that "feeling good about oneself" is the
"good," then I suppose one who acts "morally" as a means toward feeling good is acting "morally." But then that says nothing, since "feeling good" could justify any
act. That's moral relativism in a nutshell.
A moral system will often include an external authority (a God) that always lurks behind the stage, judging the actions. So a lone person is nonetheless judged by the same rules as the one involved in social environment.
I suppose if a person believes that morality is imposed by a deity, then immoral actions, even in isolation, are immoral absolutely
. But then we are certainly in a "tree falling in the forest" situation here.
Additionally, the strong claim that the immorality of actions brings down the whole of humanity is not avoided by the actor's solitude.
If the totally isolated individual cannot serve as a bad example for the rest of society, how can his actions, in a Kantian sense, "bring down the whole of humanity?"
In case of moral laws being enforced by a society, let's not forget that enforcerers of moral principles are sometimes even harder on themselves that they are on others; a lone person will be his own judge.
That's purely a matter of how much a person wishes to punish or reward himself. If we base morality on this foundation, however, we are unquestionably engaged in moral relativism.
And bad acts usually do lead to just a bad conscience, and more often not even to that. This is not _just_ a bad conscience, this is a very strong principle of moral system upholding.
Again, bad consciences are more a matter of psychology than philosophy. But to the extent that one's bad conscience is a basis for morality, it is a basis only of moral relativism.