24. Taking into account our historical overview, together with certain points of agreement identified, and the critique that has been made of gender theory, we can now move to some considerations on the issue based on the light of reason. In fact, there are rational arguments to support the centrality of the body as an integrating element of personal identity and family relationships. The body is subjectivity that communicates identity of being. [23: Cf. John Paul II, Encyclical Letter Veritatis Splendor, 6 August 1993, 48.] In the light of this reality, we can understand why the data of biological and medical science shows that ‘sexual dimorphism’ (that is, the sexual difference between men and women) can be demonstrated scientifically by such fields as genetics, endocrinology, and neurology. From the point of view of genetics, male cells (which contain XY chromosomes) differ, from the very moment of conception, from female cells (with their XX chromosomes). That said, in cases where a person’s sex is not clearly defined, it is medical professionals who can make a therapeutic intervention. In such situations, parents cannot make an arbitrary choice on the issue, let alone society. Instead, medical science should act with purely therapeutic ends, and intervene in the least invasive fashion, on the basis of objective parameters and with a view to establishing the person’s constitutive identity.
25. The process of identifying sexual identity is made more difficult by the fictitious construct known as “gender neuter” or “third gender”, which has the effect of obscuring the fact that a person’s sex is a structural determinant of male or female identity. Efforts to go beyond the constitutive male-female sexual difference, such as the ideas of “intersex” or “transgender”, lead to a masculinity or feminity that is ambiguous, even though (in a self-contradictory way), these concepts themselves actually presuppose the very sexual difference that they propose to negate or supersede. This oscillation between male and female becomes, at the end of the day, only a ‘provocative’ display against so-called ’traditional frameworks’, and one which, in fact, ignores the suffering of those who have to live situations of sexual indeterminacy. Similar theories aim to annihilate the concept of ‘nature’, (that is, everything we have been given as a pre-existing foundation of our being and action in the world), while at the same time implicitly reaffirming its existence.
26 Philosophical analysis also demonstrates that sexual difference between male and female is constitutive of human identity. Greek and Roman thinkers posit essence as the aspect of being that transcends, brings together and harmonizes male-female difference within the unity of the human person. Within the tradition of hermeneutical and phenomenological philosophy, both sexual distinction and complementarity are interpreted in symbolic and metaphorical terms. Sexual difference in relationships is seen as constitutive of personal identity, whether this be at the level of the horizontal (in the dyad “man-woman”) or vertical (in the triad “man-woman-God”). This applies equally to interpersonal “I-You” male-female relationships and to family relationships (You-I-We).
27. The formation of one’s identity is itself based on the principle of otherness since it is precisely the direct encounter between another “you” who is not me that enables me to recognize the essence of the “I” who is me. Difference, in fact, is a condition of all cognition, including cognition of one’s. In the family, knowledge of one’s mother and father allows the child to construct his or her own sexual identity and difference. Psychoanalytic theory demonstrates the tri-polar value of child-parent relationships, showing that sexual identity can only fully emerge in the light of the synergetic comparison that sexual differentiation creates.
28. The physiological complementarity of male-female sexual difference assures the necessary conditions for procreation. In contrast, only recourse to reproductive technology can allow one of the partners in a relationship of two persons of the same sex to generate offspring, using ‘in vitro’ fertilization and a surrogate mother. However, the use of such technology is not a replacement for natural conception, since it involves the manipulation of human embryos, the fragmentation of parenthood, the instrumentalization and/or commercialization of the human body as well as the reduction of a baby to an object in the hands of science and technology. [24: Cf. Congregation For The Doctrine Of The Faith, Instruction on Respect for Human Life in its Origin and the Dignity of Procreation, Donum Vitae, 22 February 1987, 4]
29. In so far as this issue relates to the world of education, it is clear that by its very nature, education can help lay the foundations for peaceful dialogue and facilitate a fruitful meeting together of peoples and a meeting of minds. Further, it would seem that the prospect of a broadening of reason to include the dimension of the transcendent is not of secondary importance. The dialogue between Faith and Reason, “if it does not want to be reduced to a sterile intellectual exercise, it must begin from the present concrete situation of humanity and upon this develop a reflection that draws from the ontological-metaphysical truth”. [25: Benedict XVI, Address to the Participants of the sixth European Symposium of University Professors, Rome, 7 June 2008.] The evangelizing mission of the Church to men and women is carried out within this horizon.