Is it really so bad to be a little bit delusional? Not according to Shankar Vedantam. In his new book, “Useful Delusions: The Power and Paradox of the Self-Deceiving Brain,” he argues that we tell ourselves lies in order to live. We believe our marriages will last, even though there’s a fifty-fifty chance we’re headed for divorce. We trick ourselves into thinking our children are extraordinary because if we saw them for who they really are — average, disobedient, smelly — the body blows of parenting would be more than we could bear. In this candid conversation with Next Big Idea Club curator Daniel Pink, Shankar says wide-eyed delusions aren’t bad for us. In fact, self-deception is part of being a well-adjusted human being.