A view that I have heard frequently as of late involves evidence. This view, to put it simply, is that scientific evidence is the only thing that can be considered as evidence. By scientific evidence, I mean events that involve observation with the five senses that can be repeated.
The problem with this view is that it unnecessarily limits the definition of evidence to observable, repeatable events. The definition of evidence involves more than those events. Evidence is basically anything that you can use to determine that a claim about reality actually matches reality.
That point does not limit the ability for observable, repeatable events to be used as evidence. As an example of this kind of evidence, say I make the claim that “whatever goes up, must come down”. I think that this claim matches reality for those living on Earth. To verify this claim, I throw a ball into the air, and sure enough, it comes down. I throw it up again, and it comes down again. Now I have evidence showing that this sort of thing continues to happen.
Then I throw up a helium balloon, and it keeps going up. Suddenly, I think I may have evidence that my claim is false, until I see the popped balloon on the street a day later. Now, I have more evidence showing that anything that comes up, must come down.
This example is definitely not a formal scientific experiment, but it does show the concept that a claim about reality can be verified through observable, repeatable events. Along with this type of evidence, we commonly use other types of evidence to verify claims.
One example is historical evidence. Like scientific evidence, some aspects of historical evidence involve repetition. For example, as we obtain multiple writings that repeat the point that the George Washington was the president of the United States, we may gather a substantial amount evidence that shows the claim “Washington was a U.S. president” matches reality.
However, this evidence does not involve repeatable events like scientific evidence does. A scientific-type claim involves the formation of a hypothesis – if one event occurs, then some particular thing will result. The evidence for this claim comes through multiple events, repeated in the same matter, that lead to the same result.
A historical claim involves the truth about an event at one period in time. The evidence for this claim comes primarily through testimonies that match the claim. Some of these testimonies, especially in ancient history, are not repeatable. You cannot ask an ancient historian to repeat his testimony about a particular event. Thus, historical claims are not necessarily verified through observable, repeatable events.
Evidence can also be acquired through personal experience. A simple example involves a person’s thoughts. If you make the claim that you are thinking of a blue bunny, there is no way I can determine the truth of that claim through scientific-type tests.
For you, however, evidence comes in the form of personal experience. You have thought of other things before, and those thoughts have always corresponded to something in reality, or at least have resembled a reality that you altered in a fictional way. So based on past experiences, when you have that thought, you can conclude that you are actually thinking of an object that matches a real bunny, with a generally fictional addition of the color blue.
There are definitely some scientific tests that give insight on thought processes. By performing various tests on the brain, you may be able to determine which sections are active when you think about something. However, at this point, those tests cannot verify the claim that you are thinking about a particular object.
Even if tests could lead to that conclusion, personal experience would still be the typical method you would use to form the conclusion that you are thinking about the object. This experience does not involve repeatable events that can be observed by anyone.
There are other types of evidence that do not involve observable, repeatable events, but I think the examples of history and personal experience are sufficient to explain the point that we often use non-scientific evidence to support a claim.