(note I've sort of tailored these creatures to better suit my needs)
Etherguants are a monster from dungeons and dragons and my namesake. They are evil, meaning they will harm innocents to achieve their goals, or for no reason at all. They are aberrations meaning they have a bizarre anatomy, strange abilities and an alien mindset. They are emaciated humanoids with a writhing mass of sensory organs coming out of their chest which grants them what amounts to 360 degree xray vision. These sensory organs possess horribly impossible shapes that damages the sanity of any humanoid who views them which is why they graciously cover these organs with a face like mask which splits open during combat.

Where it's head should be is a featureless hump, this is their energy organ, it produces all they need to survive so they don't need to eat, drink or breathe, they are completely self sufficient. On closer inspection the etherguant's body appears to be devoid of anything approximating internal organs. This empty cavity once held a young etherguant. Etherguants replicate like russian dolls, each born pregnant. It is unknown how long this process takes and how many etherguants exist presently. Etherguants both sociologically and biologically follow a strict (colour coded) caste system. With each colour possessing greater mental and magical prowess and authority than the colour below it. However even the lowliest of etherguants are geniuses by humanoid standards. Etherguants can only replicate etherguants of the same colour and have no hope of rising in authority except among it's own colour. (though they do have advanced technology I want to avoid anything based on biology because the Daelkyr already cover this)

In my campaign there is a continent that was ruled by demon lords (think what the lord of the rings would be like if there were numerous beings like Sauron but each with their own means and motives). The etherguants served as the intelligencia for these lords though they may or may not have been a very different kind of creature back then. The demon lords went to war with the dragons and were sealed and their servants went into hiding (mostly underground, bottom of ocean and other inhospitable places). The etherguants converted their entire race into an incorporeal state and fled to the deep ethereal which they are starting to return from.

Now I'll get to my point, etherguants are described as philosophers, so what schools of philosophy would they be the most interested in?
It would be best if you can sum up a philosophy in a few quotes or paragraphs.