Hume,
section X. "Of Miracles" , XI. "Of a Particular providence and of a Future State", and XII. "Of the Academical or Skeptical Philosophy" from An enquiry Concerning Human Understanding.
From Wikipedia:
And there are a number of reasons to be skeptical of human testimony, also based on experience. If a) testimonies conflict one another, b) there are a small number of witnesses, c) the speaker has no integrity, d) the speaker is overly hesitant or bold, or e) the speaker is known to have motives for lying, then the epistemologist has reason to be skeptical of their claims. (Hume 1974:390)
There is one final criterion that Hume thinks gives us warrant to doubt any given testimony, and that is f) if the propositions being communicated are miraculous. Hume understands a miracle to be any event which contradicts the laws of nature. He argues that the laws of nature have an overwhelming body of evidence behind them, and are so well demonstrated to everyone's experience, that any deviation from those laws necessarily flies in the face of all evidence. (Hume 1974:391-392)
Moreover, he stresses that talk of the miraculous has no surface validity, for four reasons. First, he explains that in all of history there has never been a miracle which was attested to by a wide body of disinterested experts. Second, he notes that human beings delight in a sense of wonder, and this provides a villain with an opportunity to manipulate others. Third, he thinks that those who hold onto the miraculous have tended towards barbarism. Finally, since testimonies tend to conflict with one another when it comes to the miraculous -- that is, one man's religious miracle may be contradicted by another man's miracle -- any testimony relating to the fantastic is self-denunciating. (Hume 1974:393-398)
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