The dumbest thing you can do is to think you're smart.
We often tend to think we know a lot of things. Things we read, hear or see on whatever source of information may be perceived as just true. However, I think that it is very important to question even the most trivial of best known things. The believe in knowledge does not just kill creativity but can also be dangerous.
I've studied Physics and there is one take-home message that I would like to share. People often hear that physicists have discovered this or that. In most cases this leads to the believe that we know how the world around us works and what it is made of. Actually we don't. The way Physics works is different: It won't tell you how things work or what they are made of, instead it will provide you with a set of tools, models, and theories, derived from observations and previous models and theories, that will often result in pretty good approximations, and predictions of what we're observing in the world around us. This is not better or worse than the truth would be, in fact it's a very pure and straight forward approach that allows us to go far beyond of what seems possible sometimes.
It would in fact be quite optimistic to think that we could understand truth, with the limitations of our nature. We perceive the world in three dimensions, are heavily dependent on language (could write a whole book on that) and have a limited set of senses - but what is worse: we're not even using them. We rely on science and studies instead, loosing more and more the ability to perceive and interpret (and believe in) the signals of our own body. You cannot convince someone that might call himself scientist who knows how thinks work of the efficacy of some compound when you just feel that it is good and right for you. Instead, the compound has to go through several stages of clinical trials, that try to measure safety, tolerability and efficacy in vitro, in animals, in humans. While I understand and appreciate this approach, I often feel like the available tools to assess these domains are not even close to be suitable for that task. As a result, a negative trial will let us know that there is no effect.
It's neither easy nor fun to discuss with someone who is fiercely convinced by something just read in an article. While it's a very good thing to read (or to gather information through other channels), that information should not just be taken for granted because it has been printed in a journal. To question that information at least every once in a while should be a habit.