I know I should know what evidence is, but I have been unable to find an in-depth definition of it.
I originally thought that it was a when an argument against a theory or hypotheses was proven false, then that would be evidence for the theory or hypothesis but I haven't found anything supporting this. Please help.
To find an in-depth definition of evidence one could look at how it is described in various on-lines encyclopedias. Here are some.
Wikipedia describes evidence in the following way:
Evidence, broadly construed, is anything presented in support of an assertion. This support may be strong or weak. The strongest type of evidence is that which provides direct proof of the truth of an assertion. At the other extreme is evidence that is merely consistent with an assertion but does not rule out other, contradictory assertions, as in circumstantial evidence.
What this tells us is that an "assertion" comes first. Evidence is something that supports an assertion. Also some evidence is strong and some evidence is weak.
Let's move to the Internet Encyclopedia of Philosophy. Victor DiFate describes evidence as:
The concept of evidence is crucial to epistemology and the philosophy of science. In epistemology, evidence is often taken to be relevant to justified belief, where the latter, in turn, is typically thought to be necessary for knowledge. Arguably, then, an understanding of evidence is vital for appreciating the two dominant objects of epistemological concern, namely, knowledge and justified belief. In the philosophy of science, evidence is taken to be what confirms or refutes scientific theories, and thereby constitutes our grounds for rationally deciding between competing pictures of the world. In view of this, an understanding of evidence would be indispensable for comprehending the proper functioning of the scientific enterprise.
Here we learn that evidence is relevant to "justified belief" and "knowledge" which "epistemology" studies. Evidence can also be used to confirm or refute scientific theories. A study of evidence from the perspective of the scientific enterprise would involve the "philosophy of science".
Lastly, let's consider what the Stanford Encyclopedia of Philosophy has to say about evidence. Thomas Kelly claims there is a "tension" about what evidence means to different people::
Moreover, it is not simply that the accounts of evidence that have been advanced by philosophers stand in at least some prima facie tension with much that is said and thought about evidence outside of philosophy. As even the cursory survey offered above makes clear, philosophers themselves have offered quite divergent theories of what sorts of things are eligible to serve as evidence.
This brings us to the OP's question: What is evidence?
There is some general agreement about what evidence is based on the first two references. It is what justifies belief and provides knowledge. It is what allows us to confirm or refute scientific theories.
However, there is also tension between the different ways people use the word evidence and as Kelly further remarks, "it is far from obvious that any one thing could play all of the diverse roles that evidence has at various times been expected to play."
Reference
DiFate, V. "Evidence" Internet Encyclopedia of Philosophy https://www.iep.utm.edu/evidence/
"Evidence", Wikipedia https://en.wikipedia.org/wiki/Evidence
Kelly, Thomas, "Evidence", The Stanford Encyclopedia of Philosophy (Winter 2016 Edition), Edward N. Zalta (ed.), URL = https://plato.stanford.edu/archives/win2016/entries/evidence/.
Welcome to PSE. Conifold's recommendation to check out Stanford is excellent. Don't hesitate. In the meantime a brief account of the nature of evidence is the following, taken from a review of Peter Achinstein's The Book of Evidence:
Two are the main planks of Achinstein's approach. The first is that for something e to be evidence for a hypothesis H, it must be the case that the probability of H given e should be higher than 1/2. That is, prob (H/e) > 1/2. So, Achinstein does not work with a positive relevance requirement. As he shows in detail, that a piece of evidence e increases the probability of a hypothesis H does not make belief in H reasonable. Rather, he works with an absolute concept of evidence: e is evidence for H only if e is not evidence for the denial of H. This is meant to capture the view that evidence should provide a good reason for belief. He is certainly right in claiming that if scientists have a concept of evidence, it is this absolute concept. The second plank of his theory is that this absolute conception of evidence is not sufficient for reasonable belief (though it is necessary). What must be added is that there is an explanatory connection between H and e in order for e to be evidence for H. To be more precise, what is also necessary is that the probability that there is an explanatory connection between H and e, given H and the evidence e, should be more than 1/2. Call E(H/e) the claim that there is an explanatory connection between H and e. Achinstein's second plank is that prob (E(H/e)/H & e) > 1/2. Briefly put, the idea is that e is evidence (a good reason) for H only if prob(E(H/e)/e & H)>1/2 and prob(H/e)>1/2. (Actually, that's not quite accurate, as Achinstein explains in detail. What needs to be added - apart from taking e to be true and not entailing H - is that the product of these two probabilities should be greater than 1/2.) (Stathis Psillos, 'The Book of Evidence by Peter Achinstein', Philosophy and Phenomenological Research, Vol. 68, No. 3 (May, 2004), pp. 740-743: 741.)
Reading_______________________________________________________________________**
Stathis Psillos, 'The Book of Evidence by Peter Achinstein', Philosophy and Phenomenological Research, Vol. 68, No. 3 (May, 2004), pp. 740-743.
Peter Achinstein, The Book of Evidence, Published by Oxford Univ Press (2003) ISBN 10: 0195171713 ISBN 13: 9780195171716. (Reprinted 2016.)
I originally thought that it was a when an argument against a theory or hypotheses was proven false, then that would be evidence for the theory or hypothesis but I haven't found anything supporting this. Please help.
Evidence is information that is relevant to judging some idea.
The standard account of how evidence is relevant is that it justifies an idea: shows it is true, or probably true or gives it some other kind of positive status.
This idea presupposes that it is possible and desirable to justify ideas: justificationism. Justificationism is bunk. An argument uses assumptions and rules that are supposed to produce conclusions that are good from those assumptions. For any given argument this requires some way of knowing that the assumptions and rules are correct. No such method exists. It entirely possible for nobody to find any problem with a theory for centuries before finding a problem with it. Newtonian physics wasn't refuted for 200 years before it was replaced by general relativity and quantum theory.
However, if you make two or more arguments and the conclusions contradict one another then there is something wrong in at least one of those arguments. This doesn't rely on any of the arguments being correct. So Karl Popper proposed that knowledge is created not by justification but by spotting problems with existing ideas, proposing solutions to those problems and criticising the attempted solutions until only one is left.
For more on non-justificationist epistemology, see
https://criticalfallibilism.com/introduction-to-critical-fallibilism/
and this Popper reading list
https://fallibleideas.com/books#popper
Evidence is information that could contradict your theory. For example, Newton's theory of gravity made predictions about the orbits of planets. Changes in the orbit of Uranus were incompatible with the model of the solar system known in the 19th century. Astronomers proposed a new model in which there was a planet further from the sun than Uranus (Neptune) and they went looking for it and found it. The evidence of the orbit of Uranus produced a problem for the existing model of the solar system. The discovery of Neptune was evidence that refuted the idea that there was a problem with Newton's theory of gravity. The orbit of Mercury was also not in agreement with Newton's theory and this problem was only solved by the discovery of general relativity. Evidence is useful when it contradicts some idea we have, either an existing theory or a criticism of that theory.
