Amanda Bryant’s Epistemic Infrastructure for a Scientific Metaphysics argues that the contemporary call to naturalise metaphysics cannot rest merely on admiration for science, hostility to intuition or a vague empiricist temperament; it requires explicit epistemological justification. Bryant’s central claim is that scientific metaphysics is preferable to “free range metaphysics” because it is governed by robust theoretical constraint, meaning that its admissible claims are narrowed by scientific practice, empirical accountability and disciplined engagement with established inquiry. She rejects two insufficient foundations: simple empiricism, because empirical evidence exists outside science and cannot by itself explain why metaphysics should be specifically scientific; and sweeping scientism, because the claim that all inquiry must imitate science is both excessive and unnecessary . The decisive case study is naturalised metaphysics itself, which engages science by integrating scientific posits, interpreting data, revising metaphysical claims in light of new evidence and reformulating metaphysical questions under scientific pressure. Bryant’s argument develops through constraint principles: weakly, robustly constrained theories are preferable when other things are equal; strongly, a theory that fails to be robustly constrained may be epistemically inadequate. These principles are defended through considerations of statistical likelihood, agreement, avoidance of substantial falsity and methodological efficiency. The resulting synthesis is that science functions like an epistemic filter, excluding poorly motivated speculative contents and improving the chance that metaphysics converges on justified theory. Bryant’s conclusion is therefore not anti-metaphysical but reformist: metaphysics can remain ambitious, but its ambition becomes rationally defensible only when scientific mooring supplies the infrastructure through which speculation is disciplined, answerable and epistemically responsible.