Abstract: In the last two decades, there has been an extraordinary outpouring of careful historical work on two of the most fundamental questions in constitutional law: (1) whether Congress may delegate open-ended discretionary power to the executive branch (or others) and (2) whether Congress may restrict the president’s power to remove high-level officials in the executive branch. The best reading of the new evidence is that there was no robust nondelegation doctrine at the founding period, if there was a nondelegation doctrine at all. Though the issue is closer, the best reading of the new evidence is that during the founding period, the Constitution was understood to authorize Congress to restrict the president’s power of removal, even over principal officers (with important qualifications). Understood in terms of its original public meaning, the Constitution almost certainly allowed Congress to grant very broad discretion to the executive branch and also permitted Congress to limit the president’s removal authority over (some) principal officers. What is remarkable is that in both contexts, no originalist on the Court has been convinced by the relevant evidence, or even seriously grappled with it. Any explanation of the apparent impotence of historical evidence in this context (or others) would be speculative, but there are three plausible accounts. The first points to a simple lack of awareness of the relevant evidence and the crucial role of epistemic communities in constitutional law. The second is Bayesian and spotlights rational updating. The third points to motivated reasoning. All three accounts offer lessons for lawyers and others seeking to marshal historical evidence to disrupt engrained judicial beliefs.