By this logic, then, if one wants to learn how to write, one should take writing classes. If one wants to learn how to be more ethical, take an ethics class. But what if -- in these areas in particular -- we are wrong? And not just wrong, but completely wrong?
Let's take ethics first. If you wanted a person to become more ethical, would you want them to take a class on Aristotle, Hume, and Kant? To discuss whether or not ethics is relative, or if there is a metaphysics of morals? No. Certainly, if your goal is to make the person more ethical, the last thing you want to convince them of is that ethics is relative. An ethics class is important if you want to learn about ethical theories, but not if you want to learn how to become more ethical yourself.
So how does one accomplish the latter?
If I were to teach a class on how to be more ethical, I would not have them reading philosophers. With one exception: Plato. I would actually have them read The Apology of Socrates, because in that work we see at work what will work to make someone more ethical. In The Apology, we get to know Socrates. We are invited to empathize with him. And when we empathize with Socrates, we are then open to reconsidering our own behaviors toward others and our own ways of thinking.
Along those lines, I would then have my students read fiction. I would have them read fiction precisely for the reasons Aristotle said fiction (mythos) is superior to history: because fiction tells us what could and ought to happen, while history only tells us what did happen. In history -- even with the mot unbiased of history writers -- we are invited to take sides; in well-crafted fiction, the characters are too complex to entirely side with one or the other. We are invited to feel at least some empathy for even the more despicable characters -- Iago goes far too far, but he is not without his reasons. More, the more complex the story, the more marked the moral impact. The reason is that complex stories make for more complex minds, and more complex minds are inevitably more open to more kinds of people and experiences and are thus more moral minds. I would also include literature from foreign cultures so that my students would more directly learn to empathize with other peoples.
But that is working in a sort of top-down manner. Which certainly has it's place, to be sure. But is there a bottom-up manner that would work in conjunction with the top-down method of reading literature? Yes. It is called etiquette and manners. We have mostly denigrated etiquette and manners as too small to concern ourselves with, but as anyone who understands complex systems (like society and the mind/brain), it is the small things that count -- it is the small things that build up into large things, and which can have butterfly effects. A person who has manners and is polite and respectful is already well on the way toward being an ethical person.
“Assume a virtue, if you have it not.
That monster, custom, who all sense doth eat,
Of habits devil, is angel yet in this,
That to the use of actions fair and good
He likewise gives a frock or livery
That aptly is put on. Refrain tonight,
And that shall lend a kind of easiness
To the next abstinence; the next more easy;
For use almost can change the stamp of nature.”
― William Shakespeare, Hamlet
As Hamlet points out, if we act as though we are something long enough, we will in fact become that thing. Act ethically, and you will become ethical. The big ethical decisions will emerge from the etiquette and manners you practice.
Thus, through a combination of having students read literature and learning etiquette and manners, it would be possible to teach those students how to be more ethical people.
Now let us turn to writing.
Having students write a bunch of random essays is perhaps the single most useless activity I can think of. You do not learn how to write good sentences by writing a bunch of bad sentences then having someone stand over you and fix those sentences for you and make you write the essay over again. This is a colossal failure, and it is how things are most typically done in writing classes. If you want people to learn how to do something, you don't have them just try to do it on their own, and have a bunch of people with skills as bad or worse than your own trying to help you. No other skill is taught that way. No, if you want people to do something right, they have to be familiar with examples of how it is in fact done right. That is, they need to read extremely well-written works, both in fiction and non-fiction. We need to spend far, far, far more time reading good writing and learning how to read well than we do writing. And all writing needs to be in response to other works. When writing was taught that way, people learned how to write well -- all people of all cultures. We have moved away from this, and the outcome is hideous and an embarrassment.
In other words, if you want to learn how to write, the last thing you should do is take a writing class. Rather, read. A lot. Read and read and read. Then write. And keep reading while you write. Find a writer you love and try to write like them. Copy well-written sentences. Then you will learn how to write well -- because you will be familiar with well-written sentences. And you won't be having your horrible writing habits reinforced by reading other terrible writers' works.
For things like ethics and writing, the last thing you want to do is be directly instructed in the area. But so long as we think all instruction must be directly in the area in which you wish to improve, we will continue to fail in these areas.