I decided to wrap up my "Mapping the fine-tuning argument" project the day before yesterday in part because I wanted to make way for a new project: I am going to blog my way through Lydia and Timothy McGrew's A Cumulative Case for the Resurrection of Jesus of Nazareth. At the link you can read it yourself.
A notice about the series: what I am going to do is read the document a little at a time and then blog on it. This method may occasionally cause me to err: I might criticize the article, then read a little further and find out that my objection was answered. If that happens, I will make a note of it and I will go back and correct my older blog post. Why am I doing it that way? Because I feel like it.
I am also not going to analyze every sentence, paragraph, or claim made in the article. For example, the introduction of A Cumulative Case begins with some historical backround on arguments for miracles. This is interesting and certainly a fine introduction to the article, but I won't spend any time analyzing it because it isn't of interest to me. What I am interested in will concern matters of fact and logic which have a bearing on whether we should conclude that Jesus was raised from the dead. The dates and reliability of the gospels have a bearing on the conclusion. David Hume's argument has a bearing on that issue. The personal opinions of 18th and 19th century philosophers and polemicists have no bearing on this issue, unless those opinions happen to include correct observations or reasoning that will help us reach a conclusion.
On David Hume
My Dad and I were watching David Blaine performing magic tricks on TV late one night. I expressed complete amazement when David Blaine appeared to bring a bird back to life. Remember that, we will discuss it later. And feel free to take two minutes to watch it yourself. Pay attention as best you can, I want to discuss it more later on.
Replying to my amazement, my dad said, "You know there's no way he's actually doing what it looks like he's doing." Behind that simple comment lies the same reasoning that lies behind the "everlasting check" David Hume set against miracle claims.
There's no way he's actually doing what it looks like he's doing. Why not? Why shouldn't we believe that David Blaine is a miracle worker? Of course Blaine has told us that he's only an illusionist and not a miracle-worker. But what if he hadn't told us that? Could we then believe David Blaine was a miracle worker? My father would say no. I would say no. David Hume would say no. Anyone with a sliver of reason and good sense would say no. So what reasoning lies beneath our answer?
The reasoning is this: all of us have an extraordinary amount of evidence that dead birds, and animals in general, cannot be brought back to life. We've seen them die. We have not seen them come back to life. On the other hand, we also have some good evidence that people can fool us. If you see a stage magician who'll reveal how they do their tricks, then you know this. So, there are two theories that can account for the apparent bird resurrection. Either (1) The bird was raised from the dead or (2) The apparent resurrection was nothing more than... apparent. Theory 1 is extremely improbable due to the overwhelming evidence that the dead stay dead. Theory 2 is not improbable, in light of the fact that we know that we can be fooled.
The argument I've just given you is like a miracle-eating acid, and it is especially deadly to miracles that are known only through the report of other people. For when we haven't seen the alleged miracle with our own eyes, we have another factor to consider: honesty.
When we see a stage magician do a trick, we certainly can't doubt our own honesty with ourselves. But when someone tells you something, that report is never as reliable as your own experience, simply because that person may be lying. And people lie all the time. So if our evidence is the report of a miracle, and we can explain the report as either a lie or a miracle, which one should we conclude? It's a lie; because we have no other evidence of miracles but lots of other evidence that lies are told. And lies aren't the only possible explanation on the table: people can be mistaken about their experience (as they are fooled by magic tricks and optical illusions, for example). Again, people are mistaken frequently, while miracles, if they occur at all, must be rare since we have no other evidence of them.
David Hume established a principle from such reasoning: "No testimony is sufficient to establish a miracle, unless the testimony be of such a kind, that its falsehood would be more miraculous, than the fact, which it endeavours to establish." Notice that Hume has "left the door open" for miracles: we can't conclude that a miracle occurred from someone's testimony unless the testimony itself is of such a kind that its falsehood would be even more miraculous than the miracle that the testimony bears witness to.
And what does that mean? I can't think of any examples that would do the trick (off the top of my head) but in abstract it means this: the evidence we have is the testimony of the miracle. The miracle is unlikely to have happened, so we normally explain the miracle report as some sort of deception. But what if we found some special kind of testimony, some kind of testimony that was incredibly unlikely to have been produced by anything other than a miracle (in fact, was so unlikely to have come about through non-miraculous means that the miracle told to us in the report is more likely to have happened than the non-miraculous generation of the miracle report itself)? In that case, we would have to conclude that the miracle occurred (Read the last sentence a few more times if you need to).
All of this discussion is simply calling attention to the fact that miracles have a low prior probability of occurring in some specific case. Usually we have on hand some other non-miraculous explanations which fit the data about as well and which have a far higher prior probability, and when an explanation meets those two conditions that means that the nonmiraculous explanation will win the title of "most likely explanation for the evidence."
Now, just because a hypothesis has an extremely low prior probability doesn't mean that the hypothesis is automatically wrong. It just means that the hypothesis needs an extraordinary amount of evidential support before it can be believed. In the lens of Bayes' Theorem (which is what the McGrews' use in their article) what this means is that the posterior probability of that hypothesis needs to be so much higher than the posterior probabilities of other hypotheses which attempt to explain the event(s) we are trying to explain. How much higher does the posterior probability have to be? The short answer is that the number has to be high enough that when we plug it into the Bayes' equation it will tell us that the hypothesis is more than 50% probable.
Now, it is NOT logically impossible for us to find evidence of good enough quality which generate a favorable posterior probability for the miraculous explanation (which would make the miracle believable). However, the evidence required to believe a miracle is a tall order.
Here's an analogy that might help: think of the various competing theories as stones. Think of evidence as being energy that propels the stones forward. Think of those stones sitting at a starting mark, just a few feet from a finish line. The stones are different sizes: some are large and heavy, some are small and light, others are in between. Now, to get a great big stone across the finish line you need lots of energy. More energy than you'd need for a light stone. That's kind of like what is going on here: the miraculous explanation of an event is extremely heavy and overbearing, and it needs a huge burst of evidence to push it across the finish line so that it can become the most likely explanation for the evidence. Sure, it can happen, but it is a big burden that will only happen under special circumstances when we have the powerful evidence we need.
I think I've gotten us to the point in which I can say that we need extremely strong evidence before we can believe the resurrection. But I want to make a further point: remember that video of David Blaine apparently raising a dead bird to life. If you didn't watch it before, watch it now before you continue. Think how it would be if you couldn't see this for yourself, if you had to take it on the word of one or a few people. When they told you the story how much detail would they include? Would they tell you that David Blaine rubbed his hands together many times before laying them on the bird? I suspect they wouldn't. And that is important, because David Blaine's hand rubbing goes a long way toward showing how the trick is done.
You see, I have a theory about David Blaine's trick. My theory is that the bird was placed in a storage freezer and its heart-rate slowed down dramatically before someone took it and put it out on the grass for Blaine and his companion to "find". When Blaine was rubbing his hands together, he was warming them up so that when he picked up the bird the heat would transfer from his hands to the bird's body. And that would make the bird "wake up" from its icy coma.
What does all this have to do with Jesus? Well, all of our evidence affirming Jesus' resurrection comes from testimony (perhaps not even eyewitness testimony) that was passed along to us. In the case of David Blaine, if we had gotten our information about the bird resurrection from eyewitnesses, we would have probably lacked the crucial information we needed to solve that case. And so it is with Jesus: if there was any peculiar evidence that proved some alternative theory about the resurrection of Jesus, we would not have it, either because Jesus' disciples honestly never saw any need to report such evidence because they didn't realize what it meant, or because they didn't want to report something damning to their beliefs.
So, those are preliminary thoughts on the subject. I'm planning on reading about Bayes' Theorem as much as I can, because the McGrews' case uses it and I have little knowledge of it.