Bold is commonly used to mean courageous or daring (a bold warrior, a bold move). It can also denote another, less admired sort of fearlessness with respect to social rules of polite or appropriate behavior. Bold behavior is forward, presumptuous, or impudent. To soften an action or remark that may overstep proper boundaries, we say “May I be so bold as to…?” Brazen suggests bold to the extreme—that is, blatantly and shamelessly engaging in or attempting acts that are criminal, immoral, or embarrassing. Brazen hypocrisy makes no attempt to conceal itself, nor do brazen defiance, brazen disregard for others’ feelings, brazen attempts at looting, or other brazen violations of the law.
Both adjectives describe someone who assumes others are honest and reliable or believes what they hear unquestioningly. Trusting connotes an innocent or naive belief that people, even strangers, have good motives and one’s best interests at heart. A trusting person is endearing, but someone who is too trusting or blindly trusting is foolish and vulnerable. Being credulous is less forgivable. It suggests an unthinking, foolish, or disingenuous tendency to believe things when there is no evidence at all that the things are true (credulous public, credulous readers, credulous supporters). When the media is said to be credulous, as it frequently is, it is being criticized for abdicating the professional responsibility to be objective and factual.
Both words refer to an inherent characteristic that makes a person likely to act in a certain way. When we say someone has a tendency, such as a tendency to overeat, or the media’s tendency to sensationalize, we mean that they have a distinct inclination to engage in or be drawn to these behaviors (which are usually weaknesses or flaws). Someone who has a predisposition has been rigged, so to speak, to develop a tendency or condition, which may or may not materialize. Typically a predisposition is characterized as innate, underlying, or, more concretely, genetic, hereditary, or biological (a genetic predisposition to diabetes). However, environmental and social factors could also make a person more likely to adopt certain behaviors (a psychological predisposition to violent behavior). When we have an ideological predisposition, ingrained ideas steer us toward certain opinions, beliefs, and values.