Darth Wong wrote:
Actually, in that example you are still asking for positive evidence, ie- evidence of rain. You conclude that it's not raising because of the lack of evidence for rain (ie- the soaked hat).
It all depends on what sort of claim is being made, actually. More elaboration on this point further down the post.
He cannot prove it is raining because the hat is wet. It may be below the dew point, or someone could be spraying a hose (assuming he does not have a priori knowledge about such things, because in reality one can simply stick one's head outside and see if it is raining). It is the classic problem of induction, and why one cannot actually know by induction, only strongly suggest. He has to construct a deductive syllogism that he can falsify. Then, and only then, because we are relying on observation and not artificially or naturally constructed categories or mathematics, can he arrive at truth value he can prove.
If he sticks his hat out of a visual null field and brings it back wet, he cannot know whether it is raining or not. He can suggest, but not know. If brings it back dry, he can be certain that it is not raining. Not there and then, anyway.
Rhetorically yes, he is looking for positive evidence of rain. But epistemologically, he is proving a negative. That is is not raining. That, I think, is where you are getting hung up.
Again, the person claiming gravity exists does in fact bear the burden of proof. Sure, it's not absolute proof, but nothing is ever absolute proof.
That is not true at all. Falsification--proving the negative--is the only absolute proof one can get when trying to explain an observed phenomena set using a cause we cannot directly observe. I cannot demonstrate that an unseen force called gravity exists by dropping a cannon ball off the tower of Pisa. I must construct a model of the universe that generates testable predictions using deduction, and then attempt to falsify the model. Because even if my predictions are true, something else could be causing it.
Proving a negative may not be what we are doing in rhetoric. However, it IS what we are doing epistemologically. This is, I think, there the both of you are becoming confused and end up talking past eachother.
Now, and here is where things get special. That system of falsification only works when you are building process models. Trying to determine the existence of a causal mechanism currently in operation that explains a set of observed phenomena which can readily be observed. There are other cases where it does not work. In some cases, the truth is literally impossible to know.
A court of law is really good example of this. I can never prove that I did not cause the death of a person named Sonya Stevens on september 17th, 2004 (assuming such a person existed in the first place, and was found dead). The mechanism for her being dead (a stabbing implement) is no longer active, so no deductive tests designed to falsify the hypothesis can be done without a specific scenario that generates said predictions.
The prosecution has the burden of proof because they are capable of constructing a scenario by which I caused her death, and then adding inductive evidence in favor of it. Said scenario generates predictions that I can falsify. For example, I could falsify the prediction that I had access to the weapon that killed her. However, that still does not mean I did not do it. I could have hidden my tracks. Another scenario could be how I killed her. I could have, for example, hired someone to do the dirty work, or hidden the murder weapon sufficiently well. The prosecution's case being accepted by the court also does not mean I did do it, but there is at least some certainty. The possibility of a false positive is minimized.
If however, I am presumed guilty and left to try to disprove a nigh infinite number of possible scenarios for my guilt... I cannot do that. However, there is little chance of a false negative.
This is not an epistemological burden of proof. It is a heuristic. A rule of thumb designed to generate the smallest number of false positives (because a false negative is preferable under any sane utilitarian calculation, and under any post-enlightenment theory of justice...unless you are Antonin Scalia).
Now, let us presume it is the 18th century. It is impossible to prove the non-existence of an object. Not a process, but an object. If I came to you in the Royal society and claimed that there was a creature in Australia with the pelt, feet, and tail of a beaver, the bill of a duck, that laid eggs, suckled its young, and had venomous spurs on its feet... You could never prove me wrong. You could generate no degree of certainty that I was not telling the truth. Instead, the burden of proof is on me, and I can drag you down under and show you a platypus. But of course, if I cannot find one, that does not mean they do not exist...
In this case, you can in fact absolutely prove the positive by showing someone a platypus, but the negative cannot be proven. Ever.
And then of course there are things so poorly defined as to be meaningless. Like garage dragons, god etc.