But this leads to the second point, which is that dissent can still be important in cases where the interventionists are initially correct. Our decision to topple the Taliban in 2001, for instance, remains the right and necessary call in hindsight, notwithstanding the debacles that followed. But that didn’t make Lee’s dissenting vote any less important — because it anticipated the disaster of our nation-building effort, the over-expansive application of the authorization to use military force, the various abuses of presidential power in the War on Terror.

Likewise, in the current moment there’s no way to know for sure whether Thomas Massie’s libertarian warnings about the House’s measures — that they’re overly broad, escalatory and liable to presidential abuse — will be borne out by events. But it’s entirely possible for arming Ukraine to be good policy and for Massie to be right that some elements of the American response to Russian aggression could go badly or disastrously astray.

Finally, dissent matters because the potential scale of a disastrous outcome in a conflict with Russia is so much greater than even the worst-case scenarios in other recent wars. Let’s say, for the sake of argument, that because of the Biden administration’s caution, there’s only a 5 percent chance that our support for Ukraine leads to unexpected escalation, to the American military’s direct involvement in the war. Whereas if you looked at the Bush administration’s policy toward Iraq in late 2002, you would have said that the odds of a war for regime change in that case were well over 50 percent.