Since we are approaching the question from two different perspectives, let’s look at it from each in turn.
On my view, the following premises are assumed as being true:
- God exists.
- Everything that exists outside of God is dependent upon Him for its existence.
- God made man in His image (with intellect and free will) for the purpose of knowing and loving Him.
On your view, since I’m assuming you are an atheist, the following premises are assumed:
- The universe is self-sufficient.
- Man is the product of the blind forces of the universe.
- The universe, along with man, has no ultimate, immutable and immaterial end.
Now, on your view, there is obviously no ground for ascribing an objective purpose to man. Implicit in the notion of objective purpose is the idea that the thing to which it has been ascribed has an immaterial and immutable end towards which it has been directed by something immutably over and beyond itself. Those last five words are key, as I will presently show.
The comparison between God and the slavemaster fails because the slavemaster is only “over” the slave in a very temporal and conditional sense. This relationship could easily be reversed or eliminated dependent upon circumstances; it is neither transcendent nor immutable. The slave’s existence is not dependent in any fundamental way on the slavemaster. If the slavemaster were to die in the middle of the night, the slave would still be there the next morning.
But in the end (assuming materialism), both are the essentially meaningless products of meaningless forces, and thus whatever ends towards which they set either themselves or one another is equally subjective and ultimately meaningless. So, yes, if the materialistic worldview is correct, then all purpose is necessarily subjective.
Now, let’s look at this from the theistic perspective. On theism, all that exists only does so because God has willed it. Further, it only continues to exist because God sustains it. Unlike the relationship of our slave/slavemaster, wherein one contingent being has dominated and assumed control of another being like itself, in this case we are facing the relationship of all contingent beings to that upon which they are contingent. Whereas the slave pursuing his own will in defiance of the slavemaster’s in no way constitutes a violation of the slave’s nature, any defiance of the very ground of his being is ultimately an act of self-negation; a violation of one’s purpose as defined by that which has immutable control over it. Man does not belong to himself.
So, assuming theism, the fact of our consciousness does not relegate our ultimate purpose to the subjective. It simply allows us to create “little purposes” which may (or may not) contradict our ultimate purpose.