i define evidence as something that either proves or disproves something, how do you define it?
The same way. The problems come when that definition isn't put into practice, when people confuse assumption and proof, when people use evidence incorrectly to prove or disprove something that the evidence itself has nothing to do with thus does not prove anything at all. A clear example of that is, for thousands of years, a volcano eruption was direct, incontrovertible evidence that the volcano gods were angry. Whoops.
Another example, a common one, is someone who uses some oil additive, like Lucas or Motorkote. They'll say, "I've used it for two years and there's been no problems." Which
really means, "My engine didn't explode, therefore ergo it works. And not only that, it works great!" which is an extreme example of an illusory corollary, as evidence that the additive works, yet it proves nothing. The only thing such a scenario proves is that there may or many not be problems, and if there are you are unaware of them.
To pretend that problems which you are unaware of cannot therefore exist, is an exercise in credulity (willingness to believe or trust too readily, especially without proper or adequate evidence; gullibility). In the case of a motor, it's junk science, but has all the markings of an oil additive religion. The only way to know if there are any problems with the engine is to use the scientific method of observation and experiment in tearing down that engine and inspecting it for wear or other problems, and comparing it to the same and other engines before and after the use of the additive. That's a lot of tearing down and rebuilding, and it's just easier to assign a quick and dirty cause and effect that satisfies one's own preconceived beliefs in the matter.
People will oftentimes use an illusory correlation (seeing a relationship between two or more random events where no such relationship actually exists) to prove cause and effect as evidence of something. They confuse cause and effect with simple coincidence, and label it as evidence. It's the bread and butter of most religions, and the cornerstone of junk science. For both scientists and religious folk alike, it's very difficult to set aside long-held beliefs in favor of the truth of scientific evidence. Refusing to believe something in the face of scientific evidence is not skepticism, it is the height of credulity.
If I pray for you every day to not get into an accident, is the fact that you didn't get into an accident evidence that my prayers worked? Of course it isn't. But people will nonetheless make that cause and effect connection and label it as evidence of truth. If a pitcher has a no-hitter going through 7 innings, don't mention it, because doing so will cause him to give up a hit in the 8th or 9th. Same thing. It's called coincidence, and a lot of people have a significant problem accepting the concept of coincidence. They'd much rather assign some other significant, more meaningful action to it. They take comfort in things that are easily explained and understandable, often dismissing the truth for what they can otherwise more easily understand or that which disrupts their beliefs. This is true of both religion and science.
