About something significant and important, I mean. Not just what you decided to wear this morning but about a real political, social or religious issue.
I was having a conversation with a friend and her view was that almost everyone will at some time have a moment of revelation about something that will dramatically change their mind about something important, and that they will swing from one view to the opposing side, even if it causes real disruption to their lives.
I thought that this was relatively rare - that there are many things that we don't necessarily hold strong views about but if challenged would say that we think is probably ok, but it is only when we have a reason to think deeply about the subject that we will come to hold a strong view. For me, an example of this is pornography - I used to think it was pretty harmless, but wouldn't strongly defend it in a debate, but since learning about its effects in more detail, I am strongly against. Likewise, my political views have shifted slightly as they have become more refined as a result of me thinking about things more deeply, but I could not envisage them doing a sweeping turn.
I also think that most of the beliefs we hold, we hold them because it suits us to do so. We don't tend to hold beliefs that make our lives inconvenient or uncomfortable. Therefore, anyone who does dramatically change their mind about something will do so because their circumstances have changed so the contrary argument suits them better, not because they have been convinced by someone else. We will all stand our ground and argue on views that suit us, and only switch sides if we see a benefit to ourselves.