How much evidence does it take to believe or to know?

[Pastabake]

I'm sure there is an equation that encompasses scepticism, cynicism and gullibility ... in relation to the numbers of people that already believe.

Initially almost no evidence will be required for at least one individual to believe in something ... until almost all believe. Mass belief in something is akin to mob mentality, once you get to critical mass people don't believe because there is good evidence to do so, they believe because everyone else does ... then for at least one individual no amount of evidence could make them believe.

This individual, like the first believer, is the seed of the counter belief ... not in the sense that they are a messiah/guru figure ... such people are almost always johnny come lately's cashing in on what is already there rather than being true visionaries .. their only vision tends to be what they can make out of it. Jesus and Buddha being prime examples.

I suspect that there is a evolutionary mechanism for this that ensures that we don't all go running off the cliffs to our deaths however plausible the reasons to do so might be.

What I guess I'm saying is that the vast majority of people require no evidence at all to believe in the majority of things they believe in. More so I'd claim that most rationalisations for said beliefs are almost always post hoc justifications.

[Londoner]

"How much evidence does it take to believe or to know?"

I don't think we ever assert 'belief' or 'knowledge' in the abstract, so there is something of a straw man in the question. We are all aware that there is no ultimate proof available for anything.

Instead, such terms are understood according to the context. If I 'know that Jesus loves me', everyone gets that this means something different to my knowing the boiling point of water or believing that the earth orbits the sun, or that the prisoner is guilty as charged. Similarly, the degree of certainty that goes with any claim of 'knowing' something is also understood according to context. If it isn't - for example if I claim I know Jesus loves me because he wrote me a letter, or that I have verified the boiling point of water through instinct, then this would provoke a discussion because this isn't the usual context for such claims.

So it's not 'How much evidence?', rather it is 'What sort of evidence?', the answer being 'That varies depending on the subject'.

[boagie]

Experience and understanding are the instruments, the quantity of time required to know depends on the objective content of the unknown.

[Philosophy Explorer]

Offhand I"d say the answer is it depends.

Statistics is often used to help decide. For myself I look for at least two independent ways to decide whether to believe like I did in a sales study and I was taught this in synthesizing chemical compounds.

[Elindeque1992]

I think experiencing it is the best bet.