Rawls, Kant, Habermas

Values must be defended, yet they are the last thing in an argument of defense, and hence withdraw themselves for any meaningful defense. This is, in fact, how I take values to be defined.

Rawls, Kant, Habermas, and other contract thinkers like Rawls that both embrace the value void contract of Hobbes, and subsequently imbue or defend it with a value, what are they doing? Such a method would seem to contradict or at least hurt itself, would it not?

The answer lies, I think, in not regarding consensus (and a universalist human outlook) as a value in itself, but a current best approximation of that void of value which we seem to desire, and then noting that it is somehow inherently embedded in the notion of the basic contract. Indeed, this would amount to a reduction of this desired state to a value void state of affairs, but this cannot surely be correct, per Nietzsche? (Because there is no such absolute thing as 'what we correctly desire'.) And indeed, I am not so sure how far this argument stretches out, from the realm of pragmatics, where it has sure footing (and even more clearly so), to the conceptually fully valid realm.