What is Evidence?

Forms of justification for rational belief can be put into five categories.

  • deductive reasoning
  • non-deductive reasoning (i.e. inductive or abductive)
  • experience
  • intuition
  • testimony (i.e. belief based on authority)

“Evidence” of the kind that Coyne is talking about is really an arbitrary restriction of rational justification. Hitchen’s razor “what is asserted without evidence can be discarded without evidence” is hoisted on its own petard, but the broader principle with rational justification in place of evidence is consistent. (It would be an example of a belief justified by an epistemic intuition, or an inference from other epistemic intuitions about how we should go about forming beliefs.)

I write a bit more about this in my blog, for anyone curious: Building Materials (I): Deductive Reasoning – Structure of Truth


You’d need premises for these. And the truth of the premises must be based on evidence, otherwise you’re just making stuff up

  • experience

Experience of what? That is empirical evidence.

  • intuition

Intuition is a reliable source of knowledge? Where’s your evidence of that?

  • testimony (i.e. belief based on authority)

Belief isn’t knowledge. There’s a fair amount belief in false authorities out there I think. And in any case, how do the authorities know stuff(supposing that they do)? By evidence.

So which of these show that GAE existed, that original sin exists, and how it is transmitted?

No because that is not a knowledge or truth-claim. It’s a method, or an operating principle. Nobody is saying “I claim to know, that what is asserted without evidence, can be discarded without evidence”.

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Testimony is a subset of evidence. A notoriously unreliable one, but evidence nonetheless.

You trust in it every day.

For mundane things, like where I put the carton of milk, or what time it is. I don’t trust it when people start blathering about seeing ghosts, gods, or space-aliens.

Testimony is evidence, if it is true. That is why perjury is a felony.

Technically testimony doesn’t have to be true to be evidence. If you had some way of verifying the truth of testimony, you wouldn’t bother with testimony. Some times all you have is testimony, and then that testimony is your only evidence. And for particularly extraordinary claims, the testimony is simply insufficient to justify belief.

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Like daily news, mandatory evacuations for firestorms, imminent flooding, hurricane or tornado warnings.

Yeah depending on the source. Some sources have shown themselves more trustworthy than others, and then there’s the problem of the consequences of a false positive. Even if I don’t know whether the source is trustworthy, if they’re telling me the building is on fire I’m probably going to leave the building because the risk of false negative outweighs it (I’d rather be fooled into temporarily leave the building, than be trapped in a burning building).

And maybe you are rejecting some sources based on disregarded corroborating evidence and flawed reasoning.

What is the empirical evidence for this statement, namely that the truth of any premises must be based on [empirical] evidence, in order for it to be true?


Most of the evidence for the GAE is based on Scriptural evidence. It’s not the kind that would convince an atheist who doesn’t think Scripture is trustworthy, but that doesn’t matter - the GAE’s target audience are Christians committed to a certain understanding of Scripture, not atheists.


Evidence- something that favors one hypothesis over another

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I think there are two main questions we have to ask. First, can the data tell us if the claim is true. Second, is the data reliable.

A quick google gives us this definition for evidence: the available body of facts or information indicating whether a belief or proposition is true or valid. This is the first requirement. The evidence has to be able to test a claim. If a fact or piece of information can’t do this for us, then it isn’t evidence. This also requires us to think about how we can falsify a claim. If a claim can’t be falsified by any conceivable fact or piece of information, then it can’t have any evidence that supports it.

Next, we have to judge the reliability of the evidence itself. Is it independent of the claim? Is there potential bias? Can it be verified? As humans, we often use shorthand and context to convey meaning, and the usage of “evidence” is no different. When people speak of evidence they are often referring to verifiable and independent evidence. For example, a defendant’s attorney can have DNA evidence re-sequenced if they don’t believe the results given by the prosecution. That is verifiable evidence. We could also ask if the police planted the evidence, and that is where we look for sources of possible conflicts of interest or bias. We also tend to look for separate sources for the evidence and the claim. If the snake-oil salesman is the only one who has tested the effects of his product, we tend to give it less weight.

Testimony sits in a really interesting middle ground. Some testimony can be verified, some not. Some testimony comes from people who have a stake in the claim being true, and some doesn’t. Human memory is a wonderful but fallible thing, so how far can we trust it? Add to that the fact that people can lie. I would fully agree that testimony is evidence in the broad sense, but there are many factors that we use to judge the reliability of that evidence.

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No controversy in any of that. We are talking about faith and trust – we are each a jury of one and need to be careful that we do not have flawed biases influencing our faith in the validity of our own analyses.

And then there’s the experience part.

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You’ve lost track of what I am responding to. The claim is that for a deductive argument to conclude in a way that it(the conclusion) would constitute knowledge, the premises of the argument must already be known to be true. And you do that by demonstrating, empirically, the truth of the premises. Otherwise it’s not knowledge.

This is not an empirical claim, this is me explaining how I define knowledge.


That is an epistemological and faith claim, more than it is a definition.

It’s also an epistemological claim. Those two categories are not mutually exclusive.

(Note my edit, adding ‘and faith’.)

You have faith in definitions? That makes no sense to me.