In an ideal world, you have conservatives and revolutionaries. The revolutionaries want to make changes to try and make things even better. The conservatives act to maintain the status quo. When they balance properly then you get steady change, but slow enough to detect and fix cascading problems/failures.

In this situation, the centralists act as the balance point, being swayed one way or the other to set the path.

Unfortunately the only place this is actually close to accurate is Sci-Fi novels.