This thread is to get clarity on whether or not one is obliged to give evidence when making a claim on RF
One only need provide evidence and any attendant argument that compellingly makes the case to support the claim (now a conclusion) if one is making an existential claim of fact, cares whether he is believed, and is dealing with a person who decides what is true about the world using evidence and reason, and is both willing and able to evaluate and be convinced by a compelling argument that would convince most people adept at critical thinking.
But under these circumstances, nobody need coax you to provide your evidence and argument, because you are motivated to provide it.
How many theists falsely claim that we atheists are always asking for proof of their god? What we a are saying is that we will not believe in gods without sufficient supporting evidence, which angers and frustrates too many of them for reasons unknown to me.
Then they tell us that we can't prove that their god doesn't exist. OK. So what? We don't need to, and most atheists don't make that claim.
giving proof is kind of a definite thing, like 100% sure (not 99.99999%), right?
If one uses that meaning for proof, it's virtually never possible to prove anything involving more than pure reason, like arithmetic and syllogism. The legal definition is more practical - beyond a reasonable doubt. I define proof as that which convinces, which reduces two mutually exclusive and logically possible statements to one. Nothing empirical ever has 100% certainty, as Descartes explained.
For a Science Teacher "1+1=2 is true" and common knowledge. For a Spiritual Teacher "God exists is true" and common knowledge
Those are different definitions of truth, the latter not useful to rational, skeptical empiricists.
Truth, for me, is the quality that all facts and only facts possess, facts being linguistic strings (sentences or paragraphs) that accurately map some aspect of reality as judged empirically. If somebody is referring to anything else when they use the word truth, I consider it unfounded claim, however sure they claim to be and whatever evidence they claim to have but haven't produced, and I call that belief faith. Faith is never a path to truth, since any idea or its polar opposite are equally well believed by faith. Since at least one of those ideas is wrong, we can see the problem with thinking this way or claiming that such ideas are true or factual.
Suppose I say that it is a fact (is true) that I live five blocks north and three blocks east of the pier. What makes it a fact? Only one thing. If I can go five blocks south and three blocks west from my front door and arrive at the pier, then my claim is a fact. Short of that, it is just a claim.
What separates facts from other statements is that facts are useful in predicting outcomes because they are anchored to observation. I can use that idea above, which was gleaned by finding my way to the pier and noting how I did it (empirically), to reliably get to the pier from home.
As I indicated, if this isn't what another person is referring to when the use words like truth and fact, then we don't really have a basis for discussion what is true since we aren't referring to the same thing, and I have no use for what such a person calls truth, because it won't be useful. If he says, "God exists is true and common knowledge," I am justified in dismissing his claim out of hand.
I am moving away from using the word truth because of the pointless directions it takes some people, who begin referring to objective truth and absolute truth and what we can never know, and undermining their own ability to think decisively, ever lost wondering what's out there beyond the theater of consciousness (noumenal reality, or Kant's ding an sich). This is the first step to intellectual paralysis.
Instead, I say that an idea is correct, confirmed, or useful if it can be used to accurately predict outcomes, with nary a thought about what's really out there beyond. It doesn't matter even if some version of brain-in-a-vat,Matrix, or last Thursdayism are correct. All that matters is that if I hold belief B that informs action A and reliably results in better predictions of outcomes than competing ideas, that idea is a keeper whatever metaphysical reality underlies that process. If I can get to the pier, what difference does it make if the pier is only a hologram, or we are part of some undescoverable computer simulation?