One's prior education turns out to effect what one currently thinks

This is all quite confused, of course.  And my confusions regarding this book are far from over!  If you're lucky you'll get to hear about more.

Kieran Setiya: the standards for being a good F may differ from the standards for being a good G, even when Fs are a kind of G.  "Even when"?  But isn't that what one would expect?  More particularly, if one were moved to think in terms of inheritance hierarchies, one would expect that (just as a square has all a rectangle's properties, and more*) the standards for being a good F would be a superset of those of being a good G. I'm not sure if that's the difference he's thinking of, partly because of that "even when" and partly because the example he gives—the standards for being a good theft are not the standards for being a good act, even though theft is a kind of act—is kind of hard to work with: what are the standards for being a good act?  (Obviously this doesn't mean a morally good act, not that that would make it any clearer what the standards are.)  Devices for measuring the length of medium-sized dry goods, and tape measures, are a more tractable G and F; whatever the standard of goodness for devices for measuring the length of such things might be, it probably includes things like accuracy, ease of use relative to the task, and a bunch of other things that we would use in assessing a tape measure, but not having a locking mechanism that holds the tape in place when engaged and allows the tape to retract when released, which is part of being a good tape measure (and not part of being a good yardstick or caliper).

Even if this post was originally motivated by a kind of silly analogy with inheritance hierarchies in object-oriented languages, that isn't the whole point. A bit later Setiya refersto the metaphysical truth that the standards for being a good F are determined by the nature of Fs, which is none to clear but at least involves the claim that there's a function from natures to standards for being good.  I, at least, have the intuition that this function is an injection, that is, that no two distinct natures have the same standards for being good.  So if Fs are a kind of G, then obviously they have different standards for being good; if they didn't, why would one think that Fs were (merely) a kind of G? Probably there are a zillion examples of different things have the same standards for being good which I'm overlooking, though. At any rate, this thought makes me find things like this confusing:

The standards for being a good disposition of practical thought might differ from the standards for being a good trait of character, even though, as I argued in section 1, dispositions of practical thought are traits of character.

(The task of the remainder being to overcome that gap.) But the traits of section one are such as: selfish, generous, callous, just. These don't seem to form a kind that is differentiable from some other group of character traits, though in context that's what you might expect the force of the statement to be.  (The reason they might differ is that the ones are kinds of the other).  They are instances of traits, but the instance-of relation is not the subclass-of relation. And if there really were a joint that separated the traits that apply to practical thought from the other traits, such that the members of the groups really were instances of different kinds of character traits, I would expect them to have different standards of being good. This all makes me very confused, as I said, about what the relation between dispositions of practical thought and character traits is supposed to be in danger of being, and what it is supposed to actually be.

*unless you think that a rectangle's properties include such things as "possibly having sides of unequal length" or something like that.