On Dictionary.com, "amplitude's" primary defintion is as follows:
Philip Wheelwright invokes the term as a metaphor for explaining why "certain particulars have a more archetypal quality than others." I've correlated this insight with my distinction between "functional" and "super-functional" modes, which appears early in this blog's history, before my acquaintance with Wheelwright, to the best of my recollection.
It occurs to me that in one previous essay, though I was not employing the term "amplitude" at all, I referred to something very similar, when I wrote that "the aspect of the combinatory-sublime may affect the way in which a given protagonist's *dynamis* is received." To illustrate this, I compared two stories in which a murder gave rise to an avenging spirit.
One was the origin story of the Spectre. As Jim Corrigan, he's murdered by mobster Gat Benson. Corrigan's spirit becomes the Spectre, who avenges his murder and then goes on to haunt other criminals as well.
The other was a stand-alone film, TOPPER RETURNS. An innocent woman, Gail Richards, is murdered by a masked man. Gail comes back as a ghost who wants to know who killed her, and so she enlists the aid of befuddled Cosmo Topper to do so. Gail's ghostly powers are much more modest than those of the Spectre, but she can turn invisible and hit people as if she were solid-- which she does in a scene where she fends off the masked murderer before he can kill again. In the end the killer is exposed as a schemer named Carrington, who didn't even mean to murder Gail, but rather her heiress friend.
In both films, the mundane murderer really has no chance to fight back against the ghostly avenger. This alone might mark both stories as subcombative going by the "Hamlet example" I cited here,though in contrast to Shakespeare's play it's the antagonist, not the protagonist, who isn't "sufficient to stand" against a superior force. If the SPECTRE story had appeared as a one-shot horror tale, I would have no problem in deeming it as just as subcombative as TOPPER RETURNS. But patently the murder of Corrigan is a setup for the Ghostly Guardian's continuing adventures, and Gail Richards' murder served no such purpose. Further, though the Spectre's mundane opponents in general aren't able to give the hero much of a fight, they still have something of a super-functional quality in that "criminals in THE SPECTRE represent more than just ordinary crooks: collectively they are the evil that forces the undead avenger to keep up his crusade, rather than going to his eternal rest."
I might have added that Gat Benson and his thugs also demonstrated greater dynamicity than Cartington, who did nothing more formidable than strangle an unskilled woman. By the principles I established here, Gat Benson and all similar mundane Spectre-opponents might be deemed as occupying the "lower level of megadynamicity," simply for having enough moxie to prove an impediment to a godlike opponent. This moxie gives all of the mundane gangsters in THE SPECTRE "the quality of being ample," for which Wheelwright's term "amplitude" may prove efficacious.
In the same essay I also wondered if the killer in TOPPER RETURNS might have registered as a more formidable opponent had he shown some "more prepossessing aspect." I neglected to mention that he does at least don a concealing hat, mask, and dark clothes to commit his murder, but I don't attribute any "quality of being ample" to these. The outfit Carrington wears is merely functional, in contrast to that of some of the other dark-clad uncanny types I've recently reviewed on my film-blog, such as 1932's THE NIGHT RIDER and 1933's THE SHADOW.