Since your explanation--Buffy oughtn't to kill people with souls--comes down to the recognition that she can (is able to) kill people with souls, I fail to see the point of all the verbiage.
Whose verbiage? I'm just explaining the show. As I've noted before, you're free to think it's asinine philosophy, or whatever. But it's what the show posited.
Buffy "oughtn't" kill beings with souls, the need for dealing with which being the purview of human-constituted authorities. ["Dead Things"] Buffy kills demons. Demons don't have souls, thus Buffy can kill them. ["Selfless"] That's essential to the show. Buffy can't kill Maggie Walsh, or Ethan Rayne, or Warren Mears, etc., even though they're all unquestionably evil, because they have souls.["Villains"] Buffy could kill Angelus (aside from her reluctance), but has strong reasons to not kill ensouled Angel, (the conflict that makes the end of "Becoming" so powerful), and Buffy may kill Spike but not ensouled-yet-murdering Spike (the conflict that drives her away from Giles ["Lies My Parents Told Me"]), and so forth. This is the Buffyverse's concept of a soul. You may think this is stupid, and I may or may not agree, but it's what the show has set up, thus it's not really arguable from a metaposition, which is what Keith was presenting. You may consider it philosophically untenable. I might agree. You may think they contradicted themselves over the course of the show(s). I'd almost certainly agree. But it's what they presented via the drama.
All Buffy is saying is that the rules for entities with souls govern her just as they govern everybody else. This rather goes without saying and the dialogue in which she has to say it has always been excessive. She mostly shouldn't lie, cheat or steal either, though sometimes she may have to.
So what are the rules for entities without souls in the there's-no-Slayer-verse? I think I need to know them before I can judge your statement's applicability.
But actually, no. She lies, cheats, and steals (not always explicitly, but metaphorically...but finally explicitly in season 8) with regularity and mostly without remorse. The show has always been fairly clear about the difference between the demands of the person (who she doesn't always take seriously) and the demands of the calling (which she takes very seriously, despite season one's dialogue). [season 1, season 2, season 3, season 4, season 5, season 6, season 7...hey, that might be a fundamental concept!]
Do you find a distinction between Spike with a chip in his head and Spike with a soul?
Viewed from an overview of both series? Not all that much. Yes, "School Hard" Spike is very different from "Fool For Love" Spike (which is perfectly understandable; "School Hard" Spike was a briefly-recurring character, not to have an in-depth arc), while "Something Blue" Spike and "End of Days" Spike are fairly similar, but both Spikes and William are a fundamental part of "Lies My Parents Told Me," and every permutation of William/Spike is evident in "Not Fade Away" and many other
AtS season 5 episodes besides. Spike's motivations in "Out of My Mind" and season 7 aren't all that different, but he's got a soul in the latter, and that's enough difference to drive drama ["Grave", "The Gift", "Beneath You," "Never Leave Me," "Touched"] but not enough to demonstrate true personality separation ["Fool For Love"].
If not, your theory about the soul in Buffy works but at the cost of having any coherent account of what soul means anymore.
Look, it's not my theory. It's right there in the text. To quote the show..."I didn't jump to conclusions. I took a small step, and there the conclusions were." Again, you're free to think it's ridiculous. That's not really my argument. I can love the show more than almost any other and think the premises are sometimes insupportable. But what Keith and I have written is what the show posits, re: the soul.
Your account of the difference between Angel and Angelus is on the face of it unsatisfactory. But if you think that way, then again your theory holds but at the cost of losing all grip on reality.
Well, it's a TV show. I'm not really sure what your foundation for complaint is. It's fiction and subject to the mutable whims of the authors. The writers and the show are quite clear about the Liam-Angelus-Angel continuity, as expressed in "Amends" and countless episodes of
Angel running from about mid-season 1 right through to "Not Fade Away." If you think it's dumb, then hate the shows' intent re: this issue. If you don't, then fine, but I don't think you've grasped what they intended. There wasn't a single Angelus/Darla/(Drusilla)/(Spike)/(Liam) flashback that didn't intend to highlight parallel behavior between desouled/ensouled entities.
Once again, an entity with no moral agency may have the memories of the prior entity with that agency, but that is not the same thing as being that person merely happening not to have moral agency.
Given all the stuff I've typed above, I can't really believe I'm saying this, but: Christ, Jonathan, it's a TV show. It's not Kant, or Genesis (not the band, the book), or real life. It's Joss Whedon's amusing notions and ways to make his characters suffer, or a bunch of writers' late-night ideas about that same suffering. I can't and won't defend the correctness or viability of what the show posits as its concept of "soul," but I can defend that definition as being the show's actual definition. If you missed it, then you missed it. If you don't agree with it, or think it's wretched, then that's what you think. But it's there. Love it, hate it, or whatever.
Keith is right about one thing. They don't lack essences. They have different essences.
I suggest to you that you failed to grasp the entirety of the Angel, Spike, Drusilla, and Darla arcs, if this is what you actually think. But you could take the shortcut and just watch "New Moon Rising," which explains everything in shorthand form.