 Because our tendency to accept testimony is innate, it is harder to overturn than Hume believes it to be. Campbell considers the case of a ferry that has safely made a crossing two thousand times. I, who have seen these safe crossings, meet a stranger who tells me solemnly that he has just seen the boat sink taking with it all on board. The likelihood of my believing this testimony is greater than would be implied by Hume’s formula for determining the balance of probabilities. Reid, a close friend of Campbell’s, likewise gave massive emphasis to the role of testimony, stressing both the innate nature of the credence we give to testimony and also the very great proportion of our knowledge of the world that we gain, not through perception or reason, but through the testimony of others. Reid’s comparison of the credence we naturally give to the testimony of others and the credence we naturally give to the deliverances of our senses, is one of the central features of his Inquiry into the Human Mind (1764).