Finally we are back on topic! Thank you, haha.
I understand your point here. Flood geology has definitely gone through some very large changes, whether in rejection of the vapor canopy model or the development of catastrophic plate tectonics. It’s a very fair question: why do I think these changes are essentially quantitative and non-essential, while the changes in the world of creationist biology are qualitative and so essential as to earn the “postcreationist” neologism?
I remember seeing a video of John Whitcomb speaking shortly before his death, at the dedication (or perhaps it was the opening?) of the Ark Encounter. It was amusing because he was going on about the vapor canopy business and of course no one said anything. Even in the world of real science, we sometimes have to let the old guard simply die off before a new paradigm can be fully embraced. That’s just human nature, I suppose.
So why don’t I think this shift is as significant? Well, the vapor canopy is not the fundamental idea of flood geology. The mechanism by which flood geology happens is separate from the underlying concept that fossil layers were deposited by the flood. That is the paradigm set up by Maurice and Whitcomb, and that is the paradigm that has been followed ever since. Advancing a different mechanism for portions of the flood and changing small details surrounding the way in which the flood forms strata is fine because it doesn’t tack against the overall current.
Imagine, however, that someone came along and began acknowledging the evidence for temporal superposition: that layers on top of other layers were clearly and unmistakably younger…and not just by a matter of hours or days. They proposed a “flood geology” in which the flood was responsible for only the tiniest fraction of the geologic column and instead insisted that the vast majority of fossil-bearing strata were post-flood deposits produced over a period of several centuries after the flood. Everything above the lowest Paleozoic layers, they argued, was post-flood deposition. They would reject as flawed virtually all the arguments for rapid deposition championed by flood geologists before them.
This wouldn’t be just a change of mechanism. They could still call this idea flood geology, but by accepting the evidence for superposition and rejecting a flood origin for the vast majority of strata, they would have gone so far from the roots of flood geology that it really would be a new idea altogether. In a sense they would simply be rediscovering the evidence for deep time, even while still trying to shoehorn it into a few thousand years.
That’s the kind of thing I’m talking about with postcreationism. The acceptance of the evidence for broad common ancestry has gone beyond the original vision of young earth creationism. Arguing that giraffes and sheep could share a common ancestor flies in the face of all creationist biology arguments ever. Same with the idea that cetaceans could have evolved from a terrestrial Ark pair, or the idea that seals and bears share a common ancestor. That’s not your daddy’s creationism at all.