The final problem in the Milesian legacy is the maintenance problem. The maintenance problem asks how the universe can retain its current orderly structure—what keeps the world acting in orderly patterns and maintaining its recognizable constancy?

Again, Anaxagoras is the first philosopher we know of to have treated this problem. According to Anaxagoras the world maintains itself through a system much like human law courts. Though opposites are constantly struggling for dominance, nature pays out retributions and penalties to keep the opposites in line, maintaining their proper balance. There is a certain natural equilibrium or balance to the world, a kind of lawfulness within nature, and nature is always striving to maintain this equilibrium. Nature, in other words, is self-regulating. Anaximinies appears to agree with this view of an inherent equilibrium within nature, or, at least, we have no evidence that he disagreed. For Heraclitus, though, the picture is much more turbulent. Instead of occasional strife, which is constantly reigned in to a peaceful equilibrium, for Heraclitus the equilibrium within nature actually is a state of constant and universal strife between opposites. The logos, the pattern or law underlying all of nature, is responsible for maintaining this stormy equilibrium.

For Parmenides, the problem of maintenance dissolves because there is no change at all in the world, but the pluralists revive the question. For Empedocles, it is the two corporeal motive forces, love and strife, that maintain order in the world, whereas for Anaxagoras that role is played by mind or nous, a rationality that controls all of nature. For the Atomists there was no need to posit any force that imposes order on the world, because they believed that order was the result of physical necessity.