John Paul IIs encyclical Fides et Ratio identifies a twofold direction in human understanding: from theology to philosophy (Chapter 2: Credo ut intellegam) and from philosophy to theology (Chapter 3: Intellego ut credam). Marc mainly follows the first directionfrom faith-assisted understanding to natural knowledge. I merely want to add a few remarks with respect to the other direction, for I think it is important to look for common ground in which to dialogue with divergent viewpoints. One may wonder whether a metaphysically oriented discourse can be sustained in an antimetaphysical environment. This was the situation of Plato in his dialogue with the Sophists. As John Finnis states, in a yet unpublished work, one cannot reasonably affirm the equality of human beings, or the universality and binding force of human rights, unless one acknowledges that there is something about persons that distinguishes them radically from subrational creatures, and which, prior to any acknowledgement of status, is intrinsic to the factual reality of every human being, adult or immature, healthy or disabled. Thus, minimal agreement on human nature seems to be both necessary and possible.
Ricardo F. Crespo, "Reply to Marc Guerra's 'The Affirmation of Genuine Human Dignity,'"Journal of Markets and Morality 4, no. 2 (Fall 2001): 301-303