Abstract: The dominant paradigm of 20th-century economics–rooted in neoclassical
equilibrium, rational agents, and closed-system modeling–faces compounding empirical and
theoretical challenges that will reshape the discipline over the coming century. Drawing on current
trajectories in complexity economics, information theory, ecological economics, behavioral science,
and artificial intelligence, this article argues that economic theory will undergo at least four
fundamental transformations by 2125: the dissolution of the rational-agent axiom in favor of
adaptive, heterogeneous agents; the reframing of economies as open thermodynamic systems
governed by entropy and irreversibility; the integration of computational intelligence as both an
analytical tool and an economic actor; and the convergence of ecological carrying capacity as an
inescapable boundary condition of all economic theorizing. The article surveys existing work in each
domain and projects forward, identifying the theoretical architectures most likely to define the
economic science of the future.
Keywords: complexity economics, thermodynamic economics, artificial intelligence,
behavioral economics, ecological economics, post-neoclassical theory