If they can't be nailed down, it is because of the lacking abilities of men's tongues to describe them, not a lack of their existence, or even their specificity.
This implies that rights exist outside of the consciousness of man, contradicting your apparent agreement with me that rights are constructed by society.
If they exist without being elucidated, then we go back to my original question: Where do they come from? And given that they are not enforceable unless society accepts them and chooses to enforce them, why should I care?
Which brings us back full circle. I therefore only care about rights that society does enforce, and rights that society, for practical reasons, ought to enforce. Arbitrary conceptions of natural rights have no meaning to me.