Random thought:
I grew up learning that you should "know what you think and why you think it". It is a reflection on our own beliefs and preconceived notions to understand why we have come to those conclusions. And I think that most of the time it has nothing to do with real thought and truly self derived opinions but instead is simply a function of being born in a certain time and place. Most of the thoughts and opinions in our heads were put there by someone else. So in a way, our own thoughts aren't really our own.
Think about some core belief that you hold and feel completely certain about. For many people this might be something religious. If you had been kidnaped as a baby and raised somewhere like Pakistan would that core belief be different? Would you still be completely certain about it?
^ this is a rhetorical question. But if you'll think about it for a moment you might see that many people hold beliefs that they are completely certain about but they could hold completely contradictory beliefs if some element that was outside of their control were changed a little bit, such as the time or place of their upbringing or the beliefs of their parents or community.
If one accepts that our own thoughts are frequently ideas put into our heads by other people, one can see the wisdom in being skeptical of information being fed us and choosing where we get our information as carefully as we chose what foods to eat. Junk food will make you unhealthy. Junk information is also bad. The problem is that information doesn't come in a package with a nutritional label on it. Like food, it's probably a good idea to get a variety information from different sources and accept that if you can't digest it you shouldn't just eat it.
