The multiverse is not merely a multiplication of worlds but a reconfiguration of explanatory space: each branch reframes causality, reassigns probability, and reorients the criteria by which we judge empirical adequacy. In this thesis I argue that treating alternate universes as ontologically significant demands a shift from singular narrative histories to a lattice of coexisting accounts, where explanation becomes a relation among patterns rather than a linear chain of events. Methodologically, this requires blending modal metaphysics with pragmatic inference: models must be judged by their capacity to map structural regularities across branches, not only by their fit to a single observed trajectory.