Odds and ends.

Probability and God.

Every once in a while I'll wind up in a discussion with someone who wants to use the probability of a scientific explanation of a past event (say, abiogenesis) being true. They want to show that the calculated probability of that event having taken place is so unbelievably large and incomprehensible that only God could have intervened to achieve the observed result.

This one is pretty easy to argue against, and doesn't require much knowledge of math, science, or theology.

If you are going to use this tactic, there are two things you need to include to make it relevant to the discussion at hand.

First: You must realize that we are talking about past events. We know something happened, and are trying to determine what that something was. Calculating the probability of that something requires a knowledge of the circumstances of that event. If we were talking about the probability of a woman having given birth to a healthy child, it would significantly alter our calculations if we were then told she was a virgin, the conception happened on the ocean floor, five million years ago, and she delivered in the vacuum of space.

Second: Because it's a past event, all calculations only make sense by comparison. You must be able to define god and calculate the probability of its existence. Then you can show, by comparison, that it is more likely than the calculation you are comparing it to. If you can't do that, it doesn't matter how many numbers you throw out there, they will be irrelevant. 

That's all, really. 

Have a nice day. :)