This article collects some of my favorite concepts and writing on the investigation of what distinguishes justified belief from opinion, epistemology

I do my best not to think in terms of true and false, binary, mutually exclusive concepts.  What I believe is better characterized with a level of confidence.  Put another way, I ask myself, "How much would I be willing to bet that I'm right?"  A few examples are in order:

Example 1: I'm highly confident I can move, draw, and fire three shots into an 8" group, near a point I choose, five yards from me, in less than 3 seconds.  I base this confidence on many repetitions, under varying degrees of pressure, sometimes without preamble or warm-up, using the same equipment I wear every day.

Example 2: I'm reasonably confident that if an opponent without significant wrestling/BJJ experience and without a large size/strength advantage, attempts to hold me in Side Control, I can either establish Guard or escape entirely.  I base this confidence on many repetitions, under high pressure against opponents with varying experience.

Example 3: I have a little confidence that I can significantly hurt an opponent by striking them with my hands or feet.  I have no experience boxing, so the best I can do is relate what I've seen others do (e.g., in MMA matches), heard others claim, or just imagine.

Attaching a level of confidence also makes it easier to perform my most important duty as a critical thinker, abandon my beliefs when it turns out I'm wrong.  If someone about my size and strength but no BJJ experience showed up at BJJ class and held me in side control for two minutes, then I have work to do before my prior level of confidence would be justified.  I need to adjust my beliefs about my place in the universe.

Jeff Atwood wrote a blog article that I've referred to in conversation many times since I first read it, Strong opinions, weakly held.  He writes about one of the best ways to get other people to help you discover and abandon incorrect beliefs: holding them strongly enough that you're willing to say 'em out loud.  If you believe something but never say it to others, you forgo that opportunity.  This is my weak point; I am uncomfortable speaking definitively enough – because I risking being wrong – to provoke this helpful effect.  Atwood is great at it, and despite the excellent example he and others provide me, I still find it difficult.

Matt Thornton asks us to consider, "What would it take to convince you that you're wrong?"  A list of logical fallacies and sophistries, and some practice recognizing and countering them comes in handy.  Abandoning your belief in favor of a less correct one – getting bamboozled or tricked – is a problem.  I'd prefer to move toward truth whenever possible.  An easy way to practice is to construct clear, specific, convincing arguments about something you already believe is wrong.  E.g., why isn't the earth flat?  More difficult is a practice Eric Raymond calls "killing the Buddha".

Find the premise, or belief, or piece of received knowledge that is most important to you right at this moment, and kill it. ... That is, imagine the world as it would be if the most cherished  belief in your thoughts at this moment were false.  Then reason about the consequences.  The more this exercise terrifies you or angers you or  undermines your sense of self, the more brutally necessary it is that you kill your belief.

Larry Correia, in Monster Hunter International, has wizened monster hunter Earl Harbinger admonish his monster-hunter recruits, "Keep your mind flexible.  Don't get caught up in what you're sure is real, because if you can't believe in them, you can't fight them."  Even in the real world, what you don't know can kill you, or hurt you, or rob you of your precious time.  Josh Waitzkin describes it beautifully in The Art of Learning with this metaphor.

I have always visualized two lines moving parallel to one another in space.  One line is time, the other is our perception of the moment. ... When we are present to what is, we are right up front with the expansion of time, but when we make a mistake and get frozen in what was, a layer of detachment builds.  Time goes on and we stop.  Suddenly we are living, playing chess, crossing the street with our eyes closed in memory.