Can you check it again "Durability criterion: a system is superior iff its operation makes the conditions for its own continued legitimate existence more durable, not less." does not read right.

 

You're right — "iff" is jargon (it's logician shorthand for "if and only if") and even when expanded the sentence is doing too much in one breath. Three problems: the biconditional is heavier than it needs to be, "its own continued legitimate existence" stacks three abstractions, and "more durable, not less" is a tic that adds nothing.

A few cleaner options, in increasing order of how much I'd rewrite:

Light touch: Durability criterion: a system counts as superior only if its operation strengthens the conditions it depends on to keep operating legitimately.

Cleaner: Durability criterion: a system is superior when its operation sustains, rather than erodes, the conditions that allow it to keep operating legitimately.

Plainest: Durability criterion: a superior system is one whose own operation doesn't undermine the conditions it needs to keep going.

I'd use the middle one in the post. It keeps "legitimately" (which is doing real work — distinguishing a system that survives by domination from one that survives by consent) and drops everything else that was just there for emphasis.

So the bullet becomes:

• Durability criterion: a system is superior when its operation sustains, rather than erodes, the conditions that allow it to keep operating legitimately.

Want me to read through the rest of the draft for similar tics?