Evidence For Dummies

I have previously discussed evidence in terms of its value in providing epistemological support for belief.  Victor Reppert takes a Bayesian view of evidence:

I understand evidence in Bayesian terms. For me, X is evidence for Y just in case X is more likely to exist given Y than given not-Y. By this definition, something can have evidence for it and be false. - Reppert

That's great.  It almost sounds as if he has justification for his beliefs, but in reality, he's just pulling the wool over the eyes of his readers.  Taking a Bayesian view of evidence is good, but it's only part of the picture, as he admits.  When analyzing evidence, you need to find the hypothesis that best accounts for all the available facts.  This is known as a scientific approach to evaluating evidence.  If there are any facts that tend to disconfirm the hypothesis, they can't be ignored (which is what theists tend to do).  Perhaps a different hypothesis would  work better - one that is arrived at by taking a more objective view of the evidence

Let's take an example.  Consider a murder scene, where the victim is found with his throat cut.  He is found in the middle of an open field that is covered with fresh snow.  There is exactly one set of footprints in the vicinity - the footprints of a young child - that lead to the victim, and away again.  A rookie detective forms the hypothesis that a young child committed the murder.  From a Bayesisan perspective, we can all agree that it is in fact more likely that we would find a child's footprints given that the child committed the murder than if the child had not committed the murder.  So the footprints are indeed evidence for this hypothesis.  But fortunately, we also have a seasoned detective on the scene who is able to look beyond that one simple piece of evidence, and take other facts into consideration.  For one thing, he notices that there are no footprints from the victim himself, and no footprints that indicate any kind of skirmish or struggle.  He notices that there is no blood on top of the snow, but there is blood on the ground beneath the snow.  As a result of these facts, he forms a different hypothesis: that the murder was committed before the snow fell, and a child came along later and found the body.  Which hypothesis better explains all of the available facts?

How about another example?  Here's a fact: some people believe in fairies.  Assume we have a hypothesis that fairies exist, and it is supported by the "evidence" that people believe in them.  The Bayesian view of evidence tells us that it is more likely that there will be people who believe in fairies if they actually exist than if they don't.  So the fact that there are people who believe in fairies counts as evidence for the existence of fairies.  True enough.  But is that evidence good evidence?  Is it sufficient to justify belief in fairies?  Hardly.  There are also people who don't believe in fairies, and you can just as well say that their non-belief is evidence for the non-existence of fairies.  So which of these hypotheses is right?  Without taking all the available information into account, you have no good basis for judgment.  You can cherry-pick a single fact - that some people believe in fairies - and use that in your Beyesian analysis of the evidence to support your hypothesis that fairies exist.  Or you can take a broader, more objective view.

Here are some things Victor considers to be reason for his belief in God, and more likely to be true if god exists:

1) The fact that we can reason about the world. The fact that it is even possible to go from evidence to a conclusion. If this isn't possible, then science isn't even possible. But that implies that our acts of reasoning are governed by the laws of logic, as opposed to the laws of physics. But naturalism says the laws of physics govern everything, and the laws of logic are superfluous as an explanation for any event in the universe.

This is based on the unjustified (and unscientific) assumption that reason can't arise from nature.  He assumes that "laws of logic" are different and separate from the laws of nature, and that they have their own causal efficacy.  He needs to read up on cognitive science, and start paying attention to the vast wealth of evidence that he has so far stubbornly refused to acknowledge.

2) That there are stable laws of nature, so that the distant past resembles the recent past. It's easy to imagine an atheistic world with no stability at all, where the laws keep changing for no reason. Why is that not the actual world?

It's also easy to imagine a world created by supernatural powers where the laws of nature don't apply.  It seems to me that the laws of nature are more indicative of naturalism than of supernaturalism.  To think that the natural behavior of the world somehow implies supernatural powers is truly a leap of logic.  To say that the laws of nature are more likely to be true given a supernatural foundation is a lie.

3) The we have just the right cosmic constants for life to emerge.

That's the opinion of believers.  It's not a fact.  Many scientists agree that there could be considerable variation in some of these constants that would still allow for the emergence of life.  But the fact is that life is finely "tuned" (or adapted) to the word in which it exists.

4) That DNA allows for gradual change, as opposed to being completely static or so radically changeable that it is completely unpredictable.

It's hard to see how this constitutes evidence for God at all.  The fact is that in the long run, we can't predict where evolutionary change will lead.  In particular, we don't know that our descendants will continue to have the same level of cognitive function that we have.  Some might even argue that it has already started to decline.  What does that tell us about God?

5) That monotheism arose against all odds in a polytheistic world in a country that hardly qualifies as a world superpower, and that it persisted in spite of the efforts of the superpowers like Assyria, Babylon, the Seleucids, and the Romans, to get it to assimilate into a polytheistic culture.

It is undeniably true that the Old Testament contains many remnants of its polytheistic origins.  But Abrahamic monotheism was heavily influenced by other religions of the period (around 650 BCE), including Zoroastrianism and Egyptian monotheistic cults.  To say that this happened "against all odds" denies the factual information.

6) That the disciples of Jesus got in the faces of those responsible for Jesus's crucifixion and told them that the Jesus they crucified was Lord and God, and lived to tell the tale and found Christianity. (If they killed Jesus, they can kill you too).

This is nothing but hearsay.  Evidence should be based on facts..

7) That archaeology has discovered that if Luke was writing a story about the founding of Christianity, it wrote it in such a way that the "research" for his "fictional" story was corroborated centuries later by archaeology, "research" that would have required him to know all sorts of detail from Jerusalem to Malta at just the right time in the first century.

All we can discern from the archaeological findings is that the author of those stories had some knowledge of the place and its recent history.  But the gospels also contain significant discrepancies between them, as well as discrepancies with known historical information.

8) That Christianity became the dominant religion of an empire in spite of getting no help, and intermittent persecution, from the political leaders of that empire, for nearly three centuries.

No help?  Does Victor suppose that Constantine imposing Christianity as the state religion played no role in its rise to dominance?

Victor pretends to have a solid foundation for his beliefs.  But he systematically ignores factual information and evidence that doesn't support that belief.  That's the only way he can conclude that all of these pieces of "evidence" are more likely to be true if God exists than if God doesn't exist.   That's the only way he and his fellow Christians can continue to believe their fairy tales in the face of everything we know in this modern era of scientific and historical knowledge.