This paper critically reexamined the foundational assumption of “linear causality” in modern science and proposes a novel theoretical framework: path integral causality. Scientific thought has gradually lost the multifaceted understanding of causation exemplified by Aristotle’s theory of four causes. Since the rise of modern science, this has culminated in a reductionist, linear model of causality that privileges straightforward cause above all. While this model has fueled technological progress, it has also fostered systemic fatigue, such as institutional rigidity, the elimination of alternatives, and a widening divide between the sciences and the humanities. In contrast, this paper applied the path integral formulation of quantum mechanics to biological evolution and the human and social sciences, proposing a nonlinear causal model that incorporates the superposition and interference of latent possibilities. Under this framework, non-reproducible phenomena — such as evolution, history, institutions, and language — are not reducible to a single causal chain but are better understood as interactions among multiple, latent potentialities. Here, unrealized possibilities are re-evaluated, and future options are preserved and unfolded in novel forms. Recent advances in quantum computing enable the concrete visualization of such nonlinear and multilayered causal structures, offering a foundation for the reintegration of the sciences and the humanities. The new frontiers facing contemporary society — space, the deep sea, and AI — can thus be redefined as synchronic spaces of coexisting possibilities under this expanded causal model. In conclusion, a science grounded in this new form of synchronic causality can transcend reductive models, providing a theoretical basis for envisioning a future rooted in diversity and ethics.
