An example of this is extreme libertarianism. For a long time, I had convinced myself that it was totally sound because if I argued politics with most people I knew, I could shut them down with logic and "prove" my case. The logic and robot-like consistency of it just reassured me that I was unassailably correct. It took me getting to the point where I realized that I didn't truly believe some of my own arguments, despite the fact that I had successfully made them countless times, to snap out of it and realize that my views, as rigidly consistent as they were, were probably disastrous from a public policy standpoint. I rationalized a position to others, which ultimately rationalized it to me as well. Don't do that.