The Diagnostic Republic reveals the hidden machinery of American governance — the drift, the forgetting, the palimpsest of obsolete rules, and the silent expansion of the administrative state. Through clear, structural analysis, Brian Padjen shows how Congress lost control of the system it built, how the bureaucracy became the primary author of daily life, and what it would take to restore a republic capable of seeing itself. This is a book for citizens who want to understand the architecture of modern power — and for leaders who must learn to maintain the institutions they inherit.