By which standard would we be measuring our internal ethical rules and external judgments that allow us to change our internal moral compass or decide not to? — Benkei
It's not so much that we have ethical rules but that we have an ethical imagination extrapolated from and moulded by the sum of interactions both that we have experienced ourselves (direct conditioning) and that we have observed others experiencing (indirect conditioning), that both results in and is sourced from a complex set of dispositions, motivations, and orientations that is always in flux and that we loosely refer to by the term "values". So, it's less like we decide to change our moral compass (even when we think we do), and more like we react to it being changed whether we consciously acknowledge that or not. As in, it's less like we're sitting at the computer console of our values typing in new programs as new stuff happens to us, and more like we're a subroutine in a larger program struggling to get a foothold in it whereby we can function optimally (and where optimal functioning is not a purely pragmatic matter of externals, but runs deeper in terms of intra- and interpersonal fit—the working out of conflicts and contradictions within ourselves and between ourselves and others, respectively). Complicating matter is the fact that our ethical imagination encompasses both our actual values and our imagined values and a complex interplay between them that results in our ethical expressions not always reflecting what we admit to ourselves and others. So, I don't know, but I think the way you've described things is likely to lead to confusion on several levels including wrt the terminology.
E.g.
Ethical view: What is this? What we think and say we value or what is shown through our behaviour that we value?
Ethical rule: A conscious expression or an internal disposition? Hard and fast principles or context-dependent orientations?
It's not condemnation and approval that rightly causes us to revisit our ethical rules (Premise 5), but it's introspection. — Hanover
It seems like that but what motivates the introspection is a change in disposition that already signals our ethical "rules" have been revisited. The introspection is then more of a working out of the conflicts this raises.
We change our internal moral compass when, through evaluation, we realize our behavior is not adhering to some higher principle. I would think we should consider the condemnation and approval of others only to the extent we evaluate the responses of others as reasonable. — Hanover
The impetus can be anything that resonates. It can be approval or disapproval, it can be something we see others do, it can be something that's done to us, or it can simply be the environment we find ourselves in especially when that changes dramatically. The point is something moves us internally and we become aware of an imbalance or conflict or contradiction, the processing of which we recognize as ethical deliberation that may or may not involve reference to "higher principles" or any other particular ethical concepts but always involves either a recalibration or reinforcing of values.
So, how do we develop our ethics?
I'd say, for the most part, they develop themselves. Our ethical imaginations are fostered or stymied with experience and conditioning—we apply them to the contexts we find ourselves in, and when that application becomes problematic, a process of change occurs which involves and may be somewhat directed by introspection. But we should resist the temptation to imagine we have much conscious control over our values, or that what we tell ourselves about them is unpolluted by the same pragmatic social concerns that caused having them to be necessary in the first place.
tl;dr There's a whole mesh of processes and interactions external and internal, interpersonal and intrapersonal that contribute both to what we say about our values and how we act in terms of values that are difficult to disentangle, and it's an oversimplification to view the changes in this overall system as a series of steps or as a bunch of switches we can turn on and off as new information is absorbed.