If you want to observe a highly interesting discussion on the Catholic conception of Tradition, go here. The 19th-20th century development in Catholic theology from a more, as they say, “static,” to “dynamic” (or “open”) view of Tradition is significant for all Christians to understand, because we are all (whether Evangelical, Catholic, or Orthodox) in the same boat in needing to re-situate our dogmas in the contemporary historical and scientific setting. The Catholic Church has, on the whole, done a better job than anyone else, steering a course between historical positivism and biblical positivism, respecting both the evidences of nature and the miracle of revelation.
Thus, in the discussion, linked above, between Arturo and Jonathan et al., I believe Jonathan is right. I don’t see how “slippery slope” accusations are helpful. It is true that Jonathan etc. are applying a kernel-husk method to protology, but does this necessarily extend, to be consistent, to christology? Not when the historical is constitutive of the dogma, and this is where the debate centers. Is the historicity of the Edenic Fall necessary for an orthodox understanding of creation, evil, and moral responsibility? Those who deny the historicity here are not inconsistent to also argue that the historicity of Christ’s bodily resurrection is necessary for an orthodox understanding of creation, justification, and reconciliation. Those who think otherwise cannot simply point-out that the apostles and most early fathers taught a Creationist protology, as if the apostolic deposit of faith contains its own inherent restrictions against a different scientific and historical setting. After all, we do allow different philosophical and semantic settings. If you believe that Tradition, for it to have any meaning, must not allow such paradigm shifts, you must argue why this is the case. That’s what I’m not seeing from the opposition. In fact, the Catholic Church especially should find such development to be unproblematic. For example, all Catholics allow for a rather extensive openness in the Tradition to accommodate the social and ecclesial situations that, in Catholic perspective, require the universal jurisdiction and infallibility of the pope (or the seven sacraments, or Mary’s sinlessness from conception, etc.). Since this is the case, why not polygenesis in human protology? I don’t see any rules restricting this development, which seems rather in line with how the Catholic Church has developed in the past.