Postmodernism is an ingenious term. It describes how we stopped believing in the idea of one truth and embraced the idea of many truths.
This one word encapsulates individualism, relativism, modern art, feminism, political polarisation, LGBT activism, post-colonialism, spiritualism and a host of other concepts.
More than anything else, postmodernism and its constant deconstruction of society's values explains why humanity never settles into a stable equilibrium.