In other words, our constitution was designed by people who were idealistic but not ideological. There's a big difference. You can have a philosophy that tends to be liberal or conservative but still be open to evidence, experience, and argument. That enables people with honest differences to find practical, principled compromise. On the other hand, fervent insistence on an ideology makes evidence, experience, and arguments irrelevant: If you possess the absolute truth, those who disagree are by definition wrong, and evidence of success or failure is irrelevant. There is nothing to learn from the experience of other countries. Respectful arguments are a waste of time. Compromise is weakness. And if your policies fail, you don't abandon them; instead, you double down, asserting that they would have worked if only they had been carried to their logical extreme.

Bill Clinton