Binary structures in myth were popularized by British anthropologist Edmund Leach and detail how core binary oppositions are mediated via mythology. Let’s break that down.
(I’ve also written articles specifically on binary oppositions and mediation — check the article list link at the bottom to access those!).
He first introduces the notion of binary pairs, which are core, shared aspects of the human experience that contradict each other in some form, or else are mutually exclusive. Life and death is a popular binary pair; as well as love and hate, order and chaos, individualism versus social responsibility, and so on. Each of these pairs represents concepts that must be considered by practically all humans and organized human systems (governments, societies, tribes). Furthermore, there is no right “answer” and each is generally a life-long struggle to settle upon some subjective equilibrium.
Because these subjects are so central to human and societal existence, these universally shared perceptions of these pairs have real, practical sway. For example, a society that views rebirth and a noble death as important may be more warlike; one that values individualism may have fewer social ties.
This is where we get into mediation, which is reconciliation of binary pairs. Put simply, mediation is figuring out a (subjective) way to understand, accept, and/or cope with a given binary opposition/pair. As mentioned, “rebirth” is a common way of understanding or mediating life and death, since death functionally ceases to exist but as a link in the cycle to fresh life. Similarly, social responsibility as the highest form of individualism and chaos as inevitable in the pursuit of order may be meditations between the pairs we touched on earlier.
Bringing these two subjects together, Leach popularized the notion that mythology is a way through which society can form its own mediations about binary pairs and pass them through subsequent generations.
He points to many popular myths to support this hypothesis and how they often deal with binary oppositions: life, death, love, chaos, responsibility, and so on. He also points to mythology as largely enduring the test of time (at least historically) via oral transmission, and how children learn about their culture, history, and what is right or wrong through stories and myths.
So, that’s it! Check out my full Religion 101 article list (useful for studying, or just learning!) here. This list includes two other articles that go deeper into mediation and binary oppositions (pairs).
