Authority and ad hominem

Argument from authority ("I'm the expert") goes hand-in-hand with the ad hominem ("you're not"). Each may be rebutted by the other, and the average quality as evidence of arguments from authority are about the same as the average quality as evidence of ad hominem. By necessity, these two kinds of evidence are the dominant forms of evidence that lead each of us as individuals to believe what we believe, since little important of what you believe comes from your own direct observation. Authority's investment costs are one good proxy measure for evaluating the value of such evidence. But contrast the law of the dominant paradigm. Perhaps the latter is superior for judging claims about the objective world, whereas investment costs are superior for judging the intersubjective.