Saturday, April 27, 2013

The Probability of the Resurrection

A Fairly Easy Task....

It is a fairly mundane task to show that the resurrection has more evidence than other ancient historical events we take for granted.

This may sound like a bold claim, but it is a rather straightforward. 

The credibility of a historical event goes up when it has both 1) documentation early after the event and 2) multiple independent sources. Of course, the earlier the event is documented after it happens, the better. And of course, the more sources you have, the better. 

Here is an example of an event that has less evidence than the resurrection:

There are about 4 primary sources for the assassination of Julius Caesar. All of them are written over 100 years after the event. 

However, there are about 4 primary sources for the resurrection, all of which are written within 70 years of the event. (70 years being an estimate made by most non-Christian scholars). 

Some attempt to rebut this by saying that the documents used for the resurrection are inherently less reliable than other Roman histories, because of the following reasons:

1) They contain contradictions between the independent sources
2) They contain miracle claims 
3) They are written by a biased party

The problem with these rebuttals is that many Roman histories have exactly the same "problems." Independent accounts of Roman events have contradictions within them. Many Roman histories contain miracle claims associated with Caesar. Furthermore, they are written by someone interested enough in the person (or Rome) to actually spend the money to write the history (it was very expensive back then). 

In light of this, it seems quite unreasonable for critics to claim that there is "not a shred of evidence for God" or "not a shred of evidence for Jesus/resurrection, etc." 

However, I don't think most people who are skeptical of the resurrection want to go this route. The real question should be something like this: "Yes, we do have more evidence for the resurrection than for many other non-miraculous historical events in the ancient world. However, is this enough evidence to prove a miraculous event such as the resurrection?" 

Therein lies the rub...

Here is where everyone's presuppositions get brought to the table. 

Christians will say "See?!?!? The resurrection is a real slam dunk. After all it has more evidence than Caesar's death!" 

Atheists will say "No not at all! The very fact that someone is claiming a resurrection inherently reduces their credibility!" 

So basically, when we mentally guesstimate how much evidence there is for the resurrection, we bring with us a big assumption about the probability of miracles in general.

How much evidence do we need for a miracle?

Many Christians and atheists perceive miracles as a "violation" of the laws of nature. Christians say that God is allowed to violate his own laws to prove he is acting in the world. Atheists say that miracles are inherently more unlikely than almost any other explanation, because the likelihood of the violation of laws of nature is so much lower than someone making a mistake in their testimony of the event.

I think both of these ideas have an element of truth to them, but are fundamentally misguided. I think they both miss the point of what a miracle actually is supposed to be. Here I have copied in another blog post to demonstrate this concept: 

The Deserted Island Metaphor 
  1. Imagine I live in a house on a deserted island. A pile of books is laying on the floor next to a bookshelf inside my house. I leave my house at 9 AM. I return home at 2 PM, only to discover that all of the books that were on the floor are now in the bookshelf. 
  2. It is impossible for books to pick themselves up and arrange themselves in a bookshelf. That would violate the laws of nature. Nevertheless, when this situation occurs, I do not simply refuse to believe that the books are really on the shelf. It's easy enough to know if books are on a shelf.
  3. This situation is called an "agent gap." It requires that an agent with the 1) power and 2) knowledge of how to assemble books on a bookshelf, entered my house and did that when I was gone.
  4. I do not need to first prove that someone came to the deserted island in order for me to prove that the books are really on the shelf. The very fact that the books are on the shelf in the first place, proves that I am not alone on the island. 
  5. We don't know if God exists. However, if we find our friend who is dead, then we talk to them the next day, a very serious "agent gap" is created. This is impossible through natural means. It requires that an agent 1) powerful enough and 2) smart enough to reassemble and reactivate the cells in a persons body, has actually done so in this case. 
  6. Like the bookshelf example, we do not need to prove the existence of God to prove the existence of a resurrected man. It's easy enough to tell if your friend is dead or alive. The very fact there is a resurrected man in the first place proves we are not alone in the universe. 
An Extension of the Deserted Island Metaphor

On this method, the initial probability of God's existence doesn't matter, as long as its not too close to zero. 

Here's why:

Imagine if I had a visitor on the island only 1 day out of 365 days. This means that the chances that someone is on the island with me is as low as 0.27% on any given day. However, if I come back to my house and discover books that had been on the floor are now assembled in a bookshelf, it simply proves that TODAY is the day that I have a visitor! 

I don't have to prove that the visitor is both on the island AND wants to assemble books in my bookshelf before proving that the books are "really" on the shelf. 

 Just seeing the books on the bookshelf makes the chances of a visitor who wants to put books on my shelf at 100%. 

This metaphor applies to God. We don't know if God exists, but as long as the probability of his existence isn't too extremely low, a well supported miracle brings the probability of his existence up to 100% (or close to it).

But Wait A Minute....

According to this theory, we could lower the probability of God's existence very very low before we would stop believing in the resurrection.

However, this approach seems to have a weakness as well.

The real question is "What if I make a mistake?" What if the books aren't really on the shelf, and I just think they are? How do we factor in the "risk" of making a mistake in this situation? What if we aren't 100% sure that the books are on the shelf, but only 98% sure??? And what if we combine this ambiguity with the probability that someone is with us on the island??
Surely, if there is a 10% chance that someone is on the island with me, and there is a 98% chance that the books that were previously on the floor are now on the bookshelf, then we would believe that a person is on the island. 

What do we do if we lower the chances to 5% that someone is on the island, and only 90% that the books are on the shelf?

I am not sure what to do in this situation. If anyone knows....please tell me!!

Is it Baye's Theorem?
I will try to look into this more and update later...

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