What is Evidence?

A statement of fact E is evidence for a theory T if E is compatable with T but ~E is not compatable with T.Unfortunately, there's a problem: being "evidence" for a theory is a very, very weak criteria and most "evidence" for a theory is so trivially weak it's not really worth mentioning. For example, that Jon is alive is evidence that Jon is the murderer, but that evidence is so weak as to be meaningless as it also applies to every other living person. Perhaps we could define the strength of evidence in terms of the extent to which it narrows possible theories down?

I must disagree, repeatability really shouldn't be taken as part of the criteria for a fact otherwise you cannot have any historicaly facts, which is silly. Nor am I sure what you expect to gain from repeatable over merely verifiable?

Trying to logical demonstrate the validity of empirical reasoning is a) not possible (see Kant), b) silly and c) circular.

It's evidence of roughly twelve trillion different things from no 1: you're no longer blind to no 12,111,834,121,649: trees have green leaves.Evidence only means anything in the context of a theory for which it is being considered as evidence.

Under this definition almost nothing is evidence. It is astonishingly rare (if even possible) for a piece of evidence to be unique to a single possible theory. I cannot think of a single example, can you?

I have no idea what you mean by "equating it to material things".According to your definition "iff X then E", E is evidence only when X is the only possible explaination of E. I cannot think of a single example of a piece of evidence for any theory ever that meets this requirement. Can you?

Anyway you like. Can you now? No. Evidence could be a material thing, or it could not be. A piece of evidence could be one thing, or it could be a trillion. A 'piece of evidence' is whatever you want to present as a 'piece of evidence' so that we can consider whether it is, in fact, evidence for your statement.Edited by Mr Jack, : Clarify

You're dodging the question I posed. Give me an example of evidence you think meets your definition, please. The only reasonable definition on that axis is whatever you've chosen to present, as I already said. Evidence, as I've said several times now, is only meaningful with respect to what it is evidence for.

Not even the individual characteristics of the rock mean your iff standard. Maybe, just maybe, if you took all the known knowledge about a geological area you could narrow things down to a single geological history, but even then you'd have uncertainty - what happened in the lost horizons? When precisely did the sea dry up? Was there a brief reversal in the drying process? Etc., etc. Now, I suppose, that you could paint your theory in such broad terms that all the possible theories that could have formed your evidence are contained; but even then you can always jump the rails and offer a ridiculous alternative (i.e. "it was martians!").So, again, I'm left asking: can you think of any evidence that means your definition? Any evidence at all?

I have no idea what an irreducible holistic bit of evidence would consist of, or why it is relevent to anything. And, yes, I'm saying that every piece of evidence is evidence of more than one thing.Now, will you please provide one single example that you think meets your 'iff X then E' criteria?

So, you're claiming that your rock is an example that meets your criteria? Well, that's clearly wrong. Yes, it could be evidence for the rock making space people, it could be evidence for the existence of a race of ancient fish with seashells instead of scales, it could be the result of a bizarre geological process that produces pseudo-organic remains, it could be the result of a mass extinction of land living shelled organisms in a massive flood. The rock alone cannot tell us. I have no idea what an irreducible holistic evidence would be, or how it's any way useful as a concept. You seem to believe that you can take the rock reduce it to a finite set of individual concepts and treat those as it's fundamental "evidences", I think that's fundamentally at odds with reality. Taking your rock, it's brute structure is powerful evidence for it's origin, but it's microscopic structure provides supporting evidence and evidence for the exact species involved, it's chemical composition provides another evidence. But if we wanted to use the rock as evidence for something else, say the law of gravity, then it's mass is suddenly relevant. And if we want to consider the geological history of the area it's from, well, it's one tiny peice of a vast jigsaw puzzle.So, once again, I come back to this: evidence is only meaningful in the context of what you are trying to present it as evidence for. Being "evidence" is not a property, irreducibly holistic or otherwise, of a thing; it's a property of what we're doing with a thing.