Confidence is generally described as a state of being certain either that a hypothesis or prediction is correct or that a chosen course of action is the best or most effective. Self-confidence is having confidence in oneself. Arrogance or hubris in this comparison is having unmerited confidence—believing something or someone is capable or correct when they are not. Overconfidence or presumptuousness is excessive belief in someone (or something) succeeding, without any regard for failure. Confidence can be a self-fulfilling prophecy as those without it may fail or not try because they lack it and those with it may succeed because they have it rather than because of an innate ability. Taken to an extreme, over-confidence can cause problems as evidenced by the famous author Matthew Syed and mentioned here in this reference in regard to sport.