Science and Other Drugs

….maybe a little less wrong….

Tag Archives: aliens

The atheist’s crutch: Misusing probability

When it becomes apparent that Christians like myself are depending primarily on history for empirical evidence of God’s involvement in history (imagine that!), atheists quite often appeal to probabilities….specifically, Bayesian probability.

Now, Bayesian probability is a complicated subject, but the relevant point here is that the probability of a particular event (or of a particular explanation being true) depends on its prior probability: the base rate of that particular event within the general population of events. Simply put, if a particular event is already known to be extremely rare, this “rareness” needs to be included in evaluating evidence for that event.

Bayes’┬áTheorem (image by mattbuck)

This becomes particularly important when we’re comparing competing explanations. Even if the evidence seems to point more toward one explanation, that explanation might not be the most probable if it was already very unlikely. For example, hearing a loud thunderous roar outside is good evidence that there’s a thunderstorm….unless, of course, you live in the desert outside Baghdad, where thunderstorms are vanishingly rare and roadside bombs are much more frequent. Read more of this post