Comment by dv_dt

In a feedback loop, every element in the loop is both a cause and an effect. The way to stop the feedback is to shift one or more relationships in the loop.

If you are lucky there can sometimes be arranged some convenient control elements- but in many difficult problems a lever that you can pull that only affects that one thing doesn't exist. You have choices of levers that affect a multitude of things, maybe many of which go counter to the desired independent effect