I thought this would be a fun idea, and an enlightening one,
as we all might find philosophical schools we hadn't heard of before. Just list
which Philosophy and philosopher you think each pony reads or is drawn to. Let me say this, each philosophy has many differing philosophers who had different slant on a certain philosophy and even though it's core principles and ideals remain the same, each philosopher has their own take
on the school. That's all. If I offend anyone I apologize in advance, I'm not a philosophy major I'm just a thinker.
Rainbow Dash-Dan Millman, Taoism
Rarity-???
Pinkie Pie- Roberto Unger, The Passions
Applejack-???
Twilight Sparkle-Plato, Ontology
Fluttershy- Socrates, Hedonism
Rainbow Dash I compared to Dan Millman, they both had to destroy their
egos in a sense to learn that doing your best is all you can do, and that winning doesn't really matter. The episode "The Mysterious Mare-Do-Well"
played with this theme extensively and as such is one of my
top ten favorite episodes.
Fluttershy just seems to enjoy life and roll with whatever comes her way; this is how she's able to be calm and collected in most everything she does.
Pinkie Pie is just fun-loving, and while I'd also count her as a extreme hedonist with reckless abandon, I settled for her being a student of The Passions because of Unger's take on the school that paraphrases as such: "The non-sequiter of The Passions is not contradictory to reason, but is simply another less ridgid side to reason."
Twilight's fascination with knowledge and learning brings her close with Ontology, in the way that she deconstructs everything to it's "spare parts" why not deconstruct the scientific theory itself, or even the nature of mind? Though I always found her use of magic and her skeptic take on most things (most notably in the episode "Pinky Keen") to be hypocritical.
As you may have noticed, Rarity and Applejack I left blank, because I find that they are quite similar and I didn't want to cheat by putting them both with a single philosophical school. Also the only philosophies I could remember off the top of my head were Machiavellianism, Humanism, Feminism, which is politically incorrect in my mind since you could say that about any of the Mane 6 in terms of being strong and independent. Humanism is sort of too ambivalent to be attributed to either pony. And Machiavellianism doesn't work with any pony. Twilight started out with Machiavellianism, but because of her unquestioning loyalty to her monarch this seemed unrealistic.