I suppose one might call the doctrine; the doctrine of coincidentia oppositorum (coincidence of opposites) from medieval Christianity and Jewish Kabbal (as in the coincidentia oppositorum of Nicholas of Cusa).
In your studies of eastern philosophies like Buddism, this philosophy can also be found in the Pair of Opposites of Buddhism (Humphreys, 1955). You may also be familiar with Taoism, and the yin-yang of classical Chinese philosophy elaborated in the commentaries of I-Ching. The yin and the yang are complementary principles or forces, explaining all processes of development and decay. Yin is the negative, passive, weak, or destructive element existing in all things, and yang the coexisting positive, active, strong, and constructive element. All change manifests an interaction between these forces; harmony is their equilibrium, conflict their opposition.
In my native religion pf Mormonism, the prophet Lehi teaches that the philosophy of opposites is at the heart of the plan of God, the fall of man was a part of the plan, otherwise man would have experienced "no joy, for they knew no misery; doing no good, for they knew no sin" (2 Ne. 2:23). Hence, Lehi concludes, "it must needs be, that there is an opposition in all things…[otherwise] righteousness could not be brought to pass, neither wickedness, neither holiness nor misery, neither good nor bad" (2 Ne. 2:11). These things are coexistant actualities that must be, otherwise neither has existence.
As a scientific principle, the theory of relativity is also based on the idea that some things do not exist without opposition. Velocity for example - a single object in a void with nothing to compare it to has no velocity. With nothing to compare it to, you cannot tell if it is moving or not. For such an object velocity is not zero – it is not undefined - Velocity literally does not exist except through opposition. Velocity is a relative concept that exists only in the presence of opposition. Good is also a relative term. Is cyanide good? Well, relative to what? for what? It’s a good thing if you are trying to refine gold ore, it’s bad if you need food. Velocity, force, good, evil, happiness, misery… does not exist without the other…