...and what if you discuss deep intellectual issues with the intent to have fun?
Warning: Longpost is long.
With all due respect to Conan (because he could twist my civilized, rotten-muscled neck off), that is best in life.
Everything is philosophy.
But to actually answer your question, I'm current playing a game with the following rules:
1) No sophistry.
2) I must work towards an end goal.
3) If my arguments are countered, I must react in a fair and rational manner.
4) Follow the rules of good debate.
So my answer is, if you're discussing to play a game, with a side effect of learning, it's gaming the discourse. That isn't what I'm doing, exactly; see below. I think my conditions mean I'm not cheating - And cheating in academics is one of the Deadlies. If you're discussing to answer the deep questions of life, it's not a game, it's...
To shift out of the game to explain, humans, in general, have a grasp of the concepts of "work" and "play". "Work" is serious business (no pun intended). Even if taken lightly, it involves situations of life-and-death - Yes, even pizza delivery. Without money, life and even survival gets a lot harder. Even if you enjoy your job and its something you'd do anyway, it's still of vital importance and does not have a primary purpose of fun - It's about responsibility.
Play is also serious business. It prepares us for situations we haven't encountered. It allows us to de-stress. And finally, it's fun. But it does those things as linked effects to its primary goal of fun. Games are play. Vitally important play and it's irresponsible to ignore play - Your mental and emotional health with suffer, sometimes to deleterious mental and emotional effects on those around you, without some form of play. But ultimately, a game must be fun. The purest (using the chemical definiton; ie, without any mixing, beneficial or otherwise) form of a game is done for no other reason than the sheer joy of playing. That is not the only form of play; mixing in other things can make a game more or less fun, or fun in different ways. But why not make a game about philosophy?
Reason and purpose are two different things. Reason is your basis for doing what you do. Purpose is what you want to achieve.
Thus, I feel my theory can be explained:
My reason for engaging in this debate is a belief that fun, itself, is valuable and that making a game about things other than fun is confusing reason with purpose.
My purpose is to convince you of my arguments.
My method is to game the debate.
A game's reason is fun.
A game's purpose is "any and all". Including fun, but also including a real enjoyment of debate and verbal maneuvering
A game's method is its rules.
A game about philosophy would have philosophy as its reason and purpose, not fun. Fun would be a method.
This further develops the idea.
Reason is why.
Purpose is what/objective.
Method is how.
With respect, in our Star Wars Saga Edition game, our Jedi came up largely without teachers. Discussing the philosophy of the Force (and by extension, Good and Evil) is a significant factor in how they stay away from falling to the Dark Side. It is very much part of the game, thank you.
You mistake my intent. All these words should help explain, or convince you I desperately need sleep.

See above; Are you discussing deep philosophy in-game to answer deep philosophical questions, or to RP your Jedi and have fun?
So, in a serious debate in a fun game with social mechanics, you have a reason, a purpose and a method.
In gaming the debate, my reason is that it keeps me from becoming too involved, my purpose is to have fun and my method is to remain within the rules outlined.
The reason I'm gaming the debate is not fun; that's just the end result I've selected based on the reason.
Now, to finally! begin to answer the question, (yeah, that's hopeful)
Bob goes to the gaming group because RPGs are fun, plays RPGs to have fun, and mostly plays games that involve deep social dynamics, because he finds that fun.
Frederick goes to the gaming group because his friends are there, plays RPGs to be socially engaged, and mostly plays kill-and-loot characters because he doesn't have to interact with the game much.
Jenny goes to the game because she's doing a paper on "Societal interactions of slave-owning societies and the effects of a theft-based economy". Her purpose is to simulate the social ramifications and her method is to enjoy the game and deep social ramifications.
Bob is playing a game, because he is engaging in play.
Frederick is playing a game, but in analysis, the game he's playing is "hang with friends", not the RPG of the moment.
Jenny is doing research for a paper. Playing the game is a method she's using to get as close to real-world research data as she wants to get. She has chosen to enjoy the game, but again, that's a method to make collection of research data easier. Playing the game is a secondary purpose for her.
If Jenny followed her reasons and purpose and made the best game for those reasons and purposes, it would be a better tool of research, and a worse game, for the same reason cheese makes terrible lettuce (I'm sure someone already has cheese that tastes like lettuce just to prove me wrong, but there's no perfect analogy. Third law of thermodynamics). The third law of thermodynamics is also my reason for this argument; if you make something better at X, it becomes harder to make it good at Y. And Jenny's purpose and reason are not the game.
I had an analogy about the Large Hadron Collider, but it limped too much, so I had to kill it and loot the body.
Now I have to re-read all that and make sure it makes sense.
tl;dr
Philosophy to game = An excuse to game.
A game with philosophy = A game with an excuse.
A game to philosophize = An excuse for philosophy.