What would you say is the most clear-cut predictor of how someone will behave in the future? If you said "past behavior," you've hit the nail on the head.  Sure, people can surprise us by radically deviating from prior behavior, but this tends to be the exception rather than the rule. For example, if your friend routinely exhibits a noticeable aversion toward silly comedies, chances are he will continue to loathe such movies. If your sister displays an acute dislike of seafood, she's bound to avoid lobster, crab, and all manner of sea creatures for the foreseeable future. When it's hard to decode a person's true intentions, you have only two tools you can leverage: your gut and, you guessed it, the person's track record. If you lure someone away from a competing firm to come work for you, rest assured they can be coaxed into bolting from yours. If someone cheats on their spouse with you, who's to say they won't cheat on you with som...