I Don't Know
I've realised that one of the most common phrases I use is "I don't know". In fact, I use it so frequently that one of my lecturers has taken to calling me "Mr I Don't Know" or "I Don't Know John".
I find that one of the hardest things people have trouble doing is admitting that we don't know. To err may be human, but it is even more human to not be omniscient — yet rather than being upfront about our lack of knowledge, we cloak our ignorance in fancy words.
I don't know why (hm, I used it again) but for some reason, I don't often have such qualms about admitting that I don't know it all. Maybe I was never scolded as a child for not knowing something, or maybe as a child I was already aware that I don't know it all, and saw nothing wrong with confessing this.
Whatever the case may be, I believe there's nothing wrong with stating that "I don't know". If anything, such admissions should be encouraged. What's truly important is avoiding the statement "I can't know", which fortunately not many people fall prey to.
The problem is that by pretending we know, when in reality we don't, we are implicitly denying that there is anything extra to know. It logically follows that we are implying that we can't know.
Just as importantly, it is not enough to stop at "I don't know". The next statement should either be a postulate — a possible answer to the question — or an explanation for why you don't know.
The only questions where there may be exceptions to this rule are questions where there is self-evidently no answer, e.g. "What is the meaning of life?" or "Why is 2 + 2 = 5?" And even then, there is a lot to be learnt simply from exploring why these questions are unanswerable.
Whenever I say "I don't know", I almost invariably follow it up with a possible answer. To take our example earlier, when I said I don't know why I frequently admit "I don't know", I hypothesised that I might never have been scolded for not knowing something as a child.
The postulated answer may be wrong, it may be right. That's not as important as attempting to find the answer in the first place. People often wonder why I do so well on tests that I've barely (or in a few cases, haven't) studied for. I normally tell them it's because I'm a professional bullshitter.
Yet, I've realised that it may also be because I dare to muse aloud. Of course I don't directly tell the examiner I don't know, but rather than strolling in with a set answer in my head, I seek to answer the question, even though at the beginning I might have no clue what the answer is.
When you admit, at least to yourself, that you don't know, and begin the process of finding the answer, I think you'll find it's a lot more rewarding than simply having the answer in your head and at your fingertips. In education and self-advancement, the end isn't always as important as how you got there.