Inner And Outer

Un-men fight political opponents of human unity. This political opposition is an external expression of psychological contradictions addressed by psychotechnicians. Ultimately, the enemy is within. See "The Old And Protean Enemy," here. Complementarily, the Order of Planetary Engineers addresses the real external enemy:

"He had meant to be a soldier in man's finest war, the fight of all men against a blind and indifferent nature which had brought their kind forth without caring."
-Poul Anderson, The Snows Of Ganymede (New York, 1958), p. 6.

(I write "the real external..." but of course nature is one and we are its self-consciousness, synthesizing subject and object, although usually experiencing antithesis, alienation and conflict.)

Aiming to serve all mankind, therefore needing to remain apolitical, the Order made itself independent of the Solar Union government and therefore survived the Humanist Revolution that outlawed the Psychotechnic Institute. Furthermore, Engineer cadets continue to receive mind training from skilled psychotechnicians - presumably also Order members.

Ironically, the Order, asked to terraform two colonized outer satellites, finds that the outlawed Institute is hiding in the outer System and that it is necessary to thwart the Psychotechnicians' plot for a violent return to power.