How did radical empiricism differ from older forms of empiricism?

William James distinguished his radical empiricism from the empiricism of earlier philosophers, such as David Hume, primarily through his treatment of relations.

While traditional empiricism often struggled to account for how experiences connect, James argued that the relations between things—whether conjunctive or disjunctive—are just as much matters of direct, particular experience as the things themselves. Consequently, he contended that the universe possesses a continuous, concatenated structure that does not require "hidden substrata" or extraneous, transempirical support to hold together.

This approach contrasts with older forms of empiricism that often viewed relations as problematic or secondary, leading some predecessors toward skepticism regarding how we justify knowledge of anything beyond our own immediate sensations. By asserting that these connections are directly apprehended parts of experience, James’s radical empiricism provides a metaphysics that refutes the rationalist belief in a transcendent being required to unify the world, positing instead that the world is held together from "next to next" by the relations found within experience itself.1