As a conservative, I have always supported the idea that minority views deserve an opportunity for expression. I admired Mr. McConnell and his Republican colleagues for avoiding the “nuclear option”—the elimination of the filibuster—when they considered it for judicial nominees in the past. I also shared their unease with having to eliminate the 60-vote rule to confirm Justice Gorsuch, even though Democrats had already done the same in 2013 for all other nominations.

But we have to look at what these remarkable events mean for the future. Can there be any doubt that Democrats will eliminate the filibuster on legislation when they next control the Senate and the White House? Last October Hillary Clinton’s running mate, Sen. Tim Kaine, pre-emptively vowed to kill the 60-vote rule this year for Supreme Court nominees.

Republicans must be clear-eyed about the risk they are taking now. If the filibuster stands, and reconciliation proves unworkable, the GOP may not be able to deliver on its promise of economic growth and jobs. Democrats may be rewarded, not punished, for their intransigence. The frustrated 2016 electorate that put Mr. Trump in office and enabled the Republicans to retain their Senate majority may not understand that the GOP failed because it didn’t have 60 votes in the Senate.