The Supreme Court’s radical shift to the right — sharply narrowing states’ ability to regulate firearms or prevent religious coercion in schools, hobbling federal efforts to fight climate change and public health threats, overruling Roe v. Wade, and much more — has brought even more insistent demands for abolishing the filibuster. Doing so now seems to be the first step in most prominent progressives’ plans for correcting what the court and the Trump administration have done or for safe...