Not the underlying notion of it, but the instances of it which we're familiar with.
I don't think we have to go with the underlying notions, which most aren't familiar with the distinctions of.
I'd expect that when people ask how things work in certain-dimensional spaces, they don't always get the answer of "We don't know, because 'dimension' has no ascribed properties or transformations by default, it's just a bunch of points on an axis."
The vast majority of people think of spatial dimensions as either "Directions of space," "The minimum number of points required to specify a location" or "A measurable extent of some kind, like length, breadth, height and width."
I don't think "Well, that's what most people think of when they hear the word" is a particularly good argument to begin with, either for or against me, but if you want to use it, unironically saying "
Actually, most people would think of a dimensional space as a set with the topological properties of being both Separable and Hausdorff" is... a pretty weird way to go about it, to say the least.
I don't understand the way you're phrasing things. I don't know what you mean by me thinking that "transcending the notion of space encompasses all possible qualitative differences". Could you point me to the post of mine that gave you this idea, so I could see that idea in my words?
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No, I do not think that we should rate every single aspatiotemporal character's AP/Dura as either Unknown or 1-A or above, when their feats of interacting with reality are consistently 9-A. And I don't think such 9-A feats would contradict them being aspatiotemporal either.
And sometimes when we're talking about things across verses, we do have to equalize things that are "Above all X" to "X". The strongest human in one verse can be fodder in another. An undefeatable technique can be easily resisted in another.
EDIT: Since it has come to my attention that this section is unclear, I should clarify. Despite the conversation having focused on Type 2 BDE, I'm taking a brief detour into Type 1 BDE, to demonstrate a contradiction with the way you're suggesting to treat Type 2 BDE. If you agree that we can equalize something "without volume" to something with a volume for Type 1, you should agree that we can do that for Type 2, at least when, in the case of Type 2, the volume-analogue we're equalizing to is above the volume that's transcended in the character's original setting. And if you don't allow that for Type 1, I'd view your suggested system as quite absurd.
Yeah, you can't equate the "size" of a character with Type 1 BDE to any volume, since they have no size at all. You can equate their power output to a volume, though, since that's unrelated to their sizelessness in the case of Type 1.
Ironically, that's a point I already anticipated in the OP, so to restate it: A character with Type 1 BDE can be 6-B for destroying Britain. They can't be 6-B for being as large as Britain, though, since that contradicts their alleged lack of dimensions. So the absurdity you're trying to demonstrate doesn't exist.
That analogy you made is also pretty terrible (Though I imagine the approachable set-up of it got you points with some of the audience). Being human is an ill-defined characteristic that doesn't inherently say anything about you, especially in fiction, unlike dimensions. Same with being an unbeatable technique.
Anyway, to go further: A higher-dimensional volume isn't equated to an uncountably infinite superiority for random reasons, as you know. It's treated as such because that's simply how volumes work when going up dimensions.
Since those mechanics can't apply to something with no volume at all, then, obviously, the claim "
Type 2 BDE can be equated to a dimensional difference" is false. And this destroys your previous claim that,
actually, the equalizations we do aren't shoddy compromises at all, and are perfectly reasonable lowballs.
Whether it can reasonably extend to all dimensions, for a given definition of that, or whether it only applies to the dimensions instantiated in the verse.
Ontop of the other points I've made, an argument for that is already up there: If a character is in a verse with a strictly finite cosmology (Say, a 5-B-sized universe), and then is stated to be "Above all finite things" (With no caveat), then treating them as finitely above the rest of the verse is absurd, since that would mean they are, themself, a finite thing. Basic application of Russell's Paradox: Something above all things X cannot be a X.
The lowest reasonable tier for that character would be High 3-A, and yet your insistence on applying statements such as these only to things that physically exist would mean they're only slightly higher into 5-B, which is plainly silly.