For one to have “proof”, they need only have what they consider evidence that is sufficient to establish that a thing is true. For some people, all they need is their parents, or some other close advisor to tell them a thing is true to produce with how I “feel” about things rather than over-analyzing it and questioning everything. I kind of envy some people that are able to operate that way, but mostly, that isn’t for me. I require thinking things through to come to my own conclusions based on whatever evidence I feel is sufficient before that evidence will produce a belief that something is true. It’s what I do all day long in IT. There’s often a lot of detective work involved. I never take a problemed server or network and decide how I feel about it to arrive at a conclusion. I instantly look at the effects, evaluate potential causes, and then arrive at the most likely conclusion. Once I’ve reached a point where I believe I have enough evidence that something is true, that’s when the feeling part comes in because I have sufficient evidence to believe in the solution to the problem, and then I act on the evidence. Generally speaking, sufficient evidence leads me to the truth.
This being said, there are some things I just don’t have time to understand for myself, so I find outside sources of evidence. I often try to find people that have thought these things through and live vicariously through their study of a subject so that I don’t have to put in the same amount of effort to come to a conclusion. Sometimes I find it difficult to conceptualize what they say I ought to believe, but because they’ve studied it so extensively, or experienced it first-hand, I feel obligated to take their word for it sometimes. If I have good reason to believe they’re not liars that are intentionally trying to mislead me for their own gain or something, I have a little faith in their experience, even though it may not yet be my own. Don’t get me wrong, I won’t take the word of just any joe on the street, it’s got to be at least an authority on the matter, or someone I trust such as a close friend. I wouldn’t take legal advice from someone who hadn’t spent plenty of time inside a courtroom, and I wouldn’t take farming advice from a lawyer.
I believe documentation and personal experience also constitute good evidence. Trusted documentation from an authority or a first-hand eyewitness is often the first thing I consult. If I believe anybody has actually had their hands on something or witnessed it, then documented it, that usually makes decent evidence. In my work, I constantly refer to the information technology eco-system for advice on difficult problems. Networking with peers is often a good source of information. Even when there is ample documentation sometimes it may be difficult to understand if it is the first time encountering a specific scenario or topic. It’s always valuable to have help from somebody who’s been there and worked through the same sort of issues.
What I’m getting at I guess, is that I really like to think things through and entirely draw my own conclusions. I like to have the sufficient evidence that could be construed as “proof”, but sometimes I have to fill gaps with other people’s knowledge, theories, and personal experience because some things just can’t be fully understood at first. I take a leap of faith and trust that even though I may not yet have or fully grasp all the evidence I feel like there’s enough circumstantial evidence to reach a conclusion. As long as I’m working with a reliable source document or subject matter expert(s), I can move to believe something is true with enough circumstantial evidence. I’m sometimes compelled to put my faith in what I feel is the best inference from the evidence for something, even though science can’t prove it to me. I’m inclined to believe it, because maybe it best fits as an elegant cause to an effect, even though I can’t see it. Maybe I can’t fully understand it, but I can I can have faith that it is there, even without the sufficient evidence physical evidence that might normally constitue proof.
Some people tell me that such unfounded belief is silly, and that I should only believe in things that can be proved. I’d be stupid to buy into something that cannot be observed by experimentation in a lab. However, reaching conclusions with solid circumstantial evidence has served me well, so I will continue to do it. Call me crazy, but I’ve come to the conclusion that I’m willing to take a leap of faith and believe in the existence of… dark energy and dark matter. I suppose it is only a matter of time before the scientists and atheists call me a fool for this faith in the unseen, since they would never do something like that, but I’ll take my chances.