Everybody is unique. But it's observable that *many* women have strong preferences for some traits in men. And *many* women are strongly repulsed by some other traits in men.
If you have too many of the repulsive traits, and not enough of the attractive traits, you are likely to find yourself effectively shut out of the dating/sex/marriage market.
Recognizing that, is the blackpill.
It's not a belief system like the red pill where you have some awareness of reality that blackpillers have, but you believe you can overcome it through the sheer power of your masculine will.
And it's not a belief system like the bluepill, where you try to block out any awareness of blackpilled reality that you might have, with some faith, belief or hope that "There's somebody out there for everybody, even meee!" and therefore, karma/the universe will eventually provide for me as long as I just keep my chin up.
I don't think a lot of people really give any of this a second thought, outside of incels, MSTOWs, and woke soys on the internet who have made hating incels a hobby.
It's just simply not an important issue to anyone who has already found their "forever" person, and it's not an important issue to anyone who is getting their needs met by the dating market or the hookup market.
So I think the blackpill is marginalized simply by the fact that most people aren't talking about it or thinking about it.
And the people who are talking about it or thinking about it, are all pretty messed up people in one way or another.
^^^ all of that is to say, I don't believe there is any "philosophy of inceldom" because there is more than one thing that can make you incel. (Of course we focus mainly on two or three of those here on this forum, I.e. height, face and race.)
So there isn't one (and only one) "type" of incel, therfore it's unlikely that we all share some philosophy.
But the blackpill I believe is the best explanation of what makes incels.