Deference done with certainty

Many experts are modest—they are uncertain whether their opinions are deference-worthy. We can’t defer to such experts by adopting their probabilities as our own, on pain of inconsistency. So how should we defer to them? This paper proposes a new deference principle for modest experts, which I call Total Certainty. Roughly, it says: If you are certain that the expert prefers option X to option Y given your total evidence, then you should prefer X to Y. I give three different characterizations of this principle and compare it with other existing deference principles.