Witness Evidence

[RoadRunner79]

---

Okay, let's say I learn about physics from the "testimony" of a professor.  I may believe what he says or I may not.  Let's say I do not-- now what?  Either he will have to demonstrate the truth of his testimony, or I will have to decide whether it's worth listening to him anymore.  The implication, and it's an important one, is that I COULD choose, at any time, to question him, and to demand a means by which to attain the knowledge through personal experience.  

Let's say a professor claims to have produced cold fusion.  I get excited and say "Show me, show me!" and he starts talking about how only he can understand the readouts on the computer, how only he has the right stuff to intepret the data, and that it is very important that I "just believe" him.  How should I respond?

The kind of testimony you are talking about lacks this important criterion: that if I don't believe, someone will be able to bring to my personal experience whatever they are testifying about.  So if I don't believe John Smith murdered Jane Doe, and have only your word for it, then I will disregard your testimony.  If I don't believe Jesus died and was resurrected three days later, then your testimony to that effect is unlikely to change my mind.

Now, in neither case does my disbelief have anything to do with the truth.  It may be that John Smith DID murder Jane Doe.  It may be that Jesus DID die and get resurrected.  However, I've met enough liars and fools in my life, and heard enough obviously false testimony, that I'm unlikely to spend much time considering hearsay.  There's just nothing in it for me.

---

Where it can reasonably be shown, this may be valid.  However the question occurs to me, how often do you do this?  I also think that if you did this often without reason to your professor he may take it as questioning his integrity; and tell you where you can go fly your kite.  And if there is a valid reason why it cannot be repeated or demonstrated to you personally, then I do think that the collaborating observational testimony of others is sufficient.  In any case, if someone is universally skeptical, it would be largely infeasible to do this for everything.

As said before, I do believe in verifying with others, and a single claim is not very strong.  Similar to in science, where they do not make hasty generalizations based on a single test.  In your example, I would say the response is reason for suspicion (there is no way to falsify the claim).  When I hear a claim that I am skeptical about, one of the first things I do is look to see if others validate (or invalidate) the claims.