 The main discussion here is framed in terms of justification rather than knowledge. The standard question is: Under what circumstances is a hearer justified in trusting an assertion made by a stranger, or by a consultant or speaker of any variety? David Hume argued that we are generally entitled to trust what others tell us; but this entitlement only arises by virtue of what we previously learned from others. Each of us can recall occasions on which we were told things that we could not independently verify (from perception, e.g.) but later determined to be true. This reliable track-record from the past (which we remember) warrants us in inferring (via induction) that testimony is generally reliable. As James Van Cleve formulates the view: