He (a friend of mine) says:
“What I’m trying to point out is that the choices each individual makes are based on the information available and the ability to predict. When the choices of two individuals are not necessarily the same, then moralily cannot be absolute, by definition.”
What he’s saying is essentially correct, though it does not yield him the conclusion he thinks it does because he is stuck in a false dichotomy between intrinsic and subjective. Which is understandable, given the approach of traditional morality, but a rational ethics must take a different approach to values and the human good. That is, it must take into account that all knowledge is contextual, and all values are agent-relative. What does this mean?
The first is fairly easy to understand: we don’t get knowledge from some lightning bolt from beyond, as Peikoff would say, or out of a vacuum, we get it out of the surroundings and particular situation of our lives. One person’s knowledge will not match another person’s knowledge, and decisions will (and must) vary accordingly.
The second is basically the difference between intrinsic values, and objective values. Usually, we have the option of intrinsic or subjective, and that’s what your friend would have us choose between. Either it is good to do one particular thing because it is good in itself (“good” as an absolute attribute of some thing or action or choice), or else there is no absolute good, everything is just subjective. But there is a third option: the good is an aspect of reality in relation to man. In that way, what is good for man is plural (can differ from person to person, situation to situation), objective (absolute and mind-independent), and agent-relative (dependent upon its effects on you). In other words, each of the abstract, substantive goods and virtues will apply differently and contextually to each specific individual person.
An example would be (just thinking off the top of my head) let us say I am offered cocaine from a drug dealer. It would not really serve my life and well-being to be doing cocaine, so I should probably reject this. Now let us say there is a different person in a different situation. He has some kind of illness, cancer or whatever, and the only way to cure it is for him to have a treatment that involves him taking cocaine. If he wants to stay alive and cure the cancer, then he should take cocaine. There is no absolute commandment “don’t do cocaine” here, it depends on the particular circumstances of each person’s flouring relative to the facts of reality.
So what does it all mean? Basically, the specific application of the generalized goods and virtues is unique to each person, and thus it’s up to each individual to make decisions based on the unique context of knowledge he has in the varied particular circumstances and situations oh his life. Each person must, to paraphrase Nietzsche, find their own mountain to climb. In other words, the moral purpose of your life is to develop the individual capacities and faculties unique to your life.