Postponing judgement

Every now and then I get into discussions with, er, …persons lacking in scientific training. A common complaint, when I decline to embrace the truth of preternatural interpretations of various events, is: “Scientists think they always know everything!” Well, no.

Saying “It must have been telepathy, what else could it be?” is assuming that everything else is known and excluded.
Saying “As all well-controlled tests so far have failed to show any evidence of telepathy, it’s unlikely that that was the cause in this case either, but the amount of detail given in your anecdote only allows us to guess on alternative explanations, so we cannot really say what happened.” is tentative, wordy, and hedging, and in particular does not assume that all circumstances are known. Why is this so difficult to grasp for some?

Then, Randy Munroe attacks another complaint about the dastardlyness of scientists:

(Of course all the facts about Fuligo septica are exactly as stated. Oh, and it’s called “troll butter” in Swedish.)