my source is personal experience and/or studying both sides of an issue.
At least in medical circles, it's virtually impossible for a layman to use that approach to consistently evaluate claims. The trick is to find reputable experts to sift stuff for you. That's why a consensus of trained professionals should carry weight.
: a psychological condition or a relationship in which a person is controlled or manipulated by another who is affected with a pathological condition (as an addiction to alcohol or heroin) ; broadly : dependence on the needs of or control by another