In my novel, I have two main protagonists, a father and son, who each have related but separate arcs developing in tandem. Each learns from the other over the course of their stories, culminating in the father’s demise which in turn leads to the son’s triumph. My question is; is it a good idea to have one Aristotelian comedy and another Aristotelian tragedy unfolding simultaneously in the one book or can that lead to a confusing experience for the reader?
If that is the story, then that is the story.
Having said that, revealing the rise and fall of each character will be a challenge. The advice to show rather than tell should be inscribed on a brass plaque and bolted to your monitor.
I would think that you, as the writer, will have to come up with situations that have clear but not obvious dimensions. As the father advances in one direction, the son advances in the other. As the son heeds the wisdom of the ages, the father plunges in unheedingly. The risk is that the writing will be "on the nose" and will bore the hell out of the reader. The goal would be to give the reader enough narration to glimpse the truth but not so much to hammer the point home.
A couple of thoughts come to mind to help you along your way. First, try to find existing works that attempt this approach; study the techniques in these works. Second, present the halves of the situations out of order; the father goes through A, B, C, D, and then E and the son goes through E, C, D, B, and A. If the situations are vivid enough and there is some rhyme to the description and dialog, the reader will make (perhaps unconsciously) the connection. Third, be prepared to edit the work ruthlessly; pulling this approach off will not be easy.
When you say "Aristotelian" what do you really mean?
For Aristotle, comedy represents human beings as "worse than they are," but he notes that comic characters are not necessarily evil, just ridiculous and laughable. He contrasts comedy with tragedy, which represents humans as "better than they are."
If this is the definition, there are some things that will be hard to do.
You may surmise from the above definition that the two types of stories portray people differently. In one as "better than they are" and in the other as "worse".
This could cause problems when jumping between the storylines. What does the author mean? What is the view of humans?
Also, the comedy making them "ridiculous and laughable" could clash badly with the tragic portrayal of people (usually as heroic, possibly victims of the whims of the gods or their own shortcomings).
However, you may also be able to pull off something like the "Pulp Fiction" scene where they accidentally kill "the guy in the back seat of the car" (don't remember his name). I guess that would be a kind of tragic comedy. (And some people love it and some hate it). Not sure that's the effect you're after though.
Going all out with comedy in one plotline and tragedy in the other will also break a kind of story form contract with the reader. If that is good or bad depends on the execution, but it will likely be much harder to do than to stay in one kind of story throughout.
Triumphant and tragic heroes
On the other hand, if you just use "Aristotelian" as a marker for different types of stories and really mean, "can I combine a story of a triumphant hero with a story of a tragic hero" then I'd say, it happens, and of course, if, like all other literature, done well works just fine.
If the father is the son's antagonist, then his tragic demise would also be something not unique or wrong (an antagonist following a negative change arc). Just because they are an antagonist doesn't mean we must hate them. Only that they don't believe in the truth we want to show in the story. But rather the lie diametrically opposite to that truth.
The problem of the antagonistic negative change arc
In my own stories, however, I've seen that making the antagonist's arc negative, instead of making them a character that does not change (a "no-arc" type of development) could detract from the hero's "win".
If the foe falls on his own devices instead of to the hero's efforts to stop him, then did the hero just got that win for free? Generally, a really, really bad idea in writing, to give heroes wins for free... especially if it's the final battle! Unless it's a comedy, then it could work great... comedy is very different... and strange... :)
Here's a picture I use from time to time: Your story's message is a gleaming hot piece of iron. The antagonist is the anvil and the hero is the hammer. If the antagonist, the anvil, does not remain steadfast and strong, the hammer won't have anything to work the metal against. The message, the whole execution (?) would become flimsy. Watching a smith trying to shape a piece of metal with just a hammer or with a failing anvil would become comedy, at best.
So you should probably find some good examples of antagonists following negative change arcs to not make it look like a giveaway to the protagonist...
A side note on Aristotelian comedy
The term "Aristotelian comedy" is a bit tricky, mainly because "Aristotle's Comedy" (the proposed "second part" of the Poetics) is a lost/never written work. He never defined comedy, per se, and all we know about comedy is derived from other parts of the Poetics.
All stories are about change. A character must learn something (usually about themselves), to overcome an obstacle. A tragedy is when the character don't change, or learn "the wrong thing".
You can have two characters working for the same thing, and let one of them fail (lack of change) and the other succeed. In that case, the tragedy is there to further prove the importance of the change/theme of story. But only one of them will be the protagonist.
I don't think it is possible for the human brain to really identify with/relate to/root for more than one character at a time in a story, so most stories really have only one TRUE protagonist. (Although Game of Thrones makes it hard to justify that point to myself. Could be argued that that is several stories, though.)