Testimony is Evidence

[LadyForCamus]

Can you determine, on the basis of my testimony alone, whether or not it would be rational to believe that I had a cheeseburger?  

Walk us through the rational process, without exceeding the limits of the claim "I had a cheeseburger".  Keep in mind, the moment you reference something exterior to those four words, you've made a liar of yourself.  Good luck.

I have 6 a priori reasons to believe your statement that you had a cheeseburger.

1. All statement of what people had for lunch are overwhelmingly more true than false.
2. Truthfulness is a presupposition for the use of language. Deviation from truth can only be done in very small doses or language would lose its usefulness. 
3. My experience is that I have not been mislead previously on similar things so I have not developed a warranted constraint on accepting such statements.
4. It is reasonable to assume that you have been raised with and adhere to a basic moral development that includes, at the very least, honesty and concern for others--which is trivially easy to learn because of the obvious benefit of receiving accurate information.
5. It would be a rare occasion that lying about such a thing would be a benefit. I did not ask for the information, I will not act on the information, and the information has no value to me. In the absence of possible known motivations for lying, I have warrant to believe you.
6. I have prior knowledge that eating a cheeseburger is a plausible act. 

So, it would be reasonable to believe you.

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This conclusion is completely circular and meaningless.  You're essentially saying:

1. Witness testimony is wrong sometimes 
2. We don't know when it will be wrong
3. Therefore, we must be careful not to accept wrong testimony, and only accept correct testimony

Your conclusion is just a re-stating of your premises, and to further its pointlessness, you offer no objective means of distinguishing between reliable/unreliable testimony as all your metrics are totally subjective:  character, track record, etc., experience.  

Totally valid argument.  You've essentially logically argued into existence that witness testimony is unreliable as a form of evidence, lol.  

Thanks!  😁

The phrase "when relying solely on witness testimony" is a key component to 3' and cannot be left out in your reformulation without substantially changing the meaning.

It is certainly no circular. It's probably the fact that it is so obvious that makes it seem that way. 

"Care" (from 3') would include assessing background information that helps us determine if we can rely on it: the witness's character, cognitive ability, subject knowledge, experiences, and track record as well as the context of the event. If these things do not increase the likelihood of truth, then by all means reject the testimony. The point is that the GB's 3 does not allow for this possibility at all.

Damn!  I really thought I had something there, haha!  😛  But, my failed take down doesn't change what I was saying before; that all of this is theoretical, and based on heavily subjective metrics. Your conclusion basically says, "don't accept unreliable testimony." What practical purpose does that serve? How does that advance our ability to distinguish between good and bad testimony in any real world capacity? How do you suppose we apply this? By using more testimony?

 You say, "if these things do not increase the likelihood of truth," but you have no actual way of measuring or quantifying results. You have no way to demonstrate that "being careful", what ever that means (all this "background info" is similarly subjective, and so it may mean something different to you than it means to me) is a MORE reliable method, or at least AS reliable a method to the truth of a claim as simply withholding belief until stronger evidence arises.  All you have is syllogism hanging in space.