Why You Don’t Have To Check Every Nutty Claim

going-to-hellA friend once earnestly invited me to his very fundamentalist church. I was a Christian at the time but, according to his church, I was not the right kind of Christian and was destined for hell. He said to me, “With the stakes so high, doesn’t it make sense to come check it out?”

He had a point, but I declined.


In the language of my last post, I was only in a position of “may believe.” I did not have compelling evidence one way or the other, but I did have enough facts in hand that I felt I could say, “I may believe (I give myself permission to believe) that his church is wrong, and I am OK.”

Wouldn’t it have been safer to get to a position of “must believe” — to investigate so thoroughly that the evidence became overwhelming one way or the other? Of course, but there are only 24 hours in a day and there are many high-stakes decisions to make. Maybe Islam is the right religion and I should convert. Maybe there’s going to be a nuclear war and I should build a bunker and stockpile supplies. Maybe there will be a tornado in Massachusetts tomorrow and I should get out of state.

In my imperfectly informed opinion, all of those events are so unlikely that I don’t need to spend time on them.

That much is intuitively obvious, but there is a further consideration that most people ignore, which is the danger and cost of arriving at the wrong conclusion.

Let’s say that there is only a 1-out-of-1,000 chance that my friend’s religion is the correct one (there are many religions, and his is pretty outlandish), but let’s also say that I’m smart and open-minded, so if any given religion is correct then my investigations would have a 100% chance of identifying it as such. I’m also so immune to being boondoggled that if a religion is false, I have only a 1% chance of concluding it’s true.

Now let’s say that I check my friend’s religion out and conclude, “Wow! These people are right!” What do you think the chances are that I have found the correct religion?

100%, right?

You might be surprised to learn that there is only a 1-in-11 chance that I’m right. In other words, I have a 10-in-11 chance of committing my life to something that is completely false.

This would not be a big deal if I were only wrong about whether leprechauns exist, but what we’re talking about here is a religion that will consume a significant portion of my time, talent and treasure. Furthermore, it will alienate me from most of my friends, who I will now think are destined for hell.

The math on this is not hard to follow. Suppose there are 1,000 religions (including one non-religion of atheism). One of them is true, but 999 are false. Now 1,000 clones of me set out to investigate each one.

There are 999 false religions, but remember that I have a 1% chance of thinking that a false religion is true. 1% of 999 is 9.99. Let’s round that up to 10. Ten of me have signed up for a false religion.

The good news is that my clone who checked out the true religion definitely concluded that it’s true.

Where do we stand? Eleven of me thought they had found the right religion, but only one was right. So if I (the real I, not my clones) were to conclude that my friend’s religion is right, then I should admit that there is a 10-in-11 chance that I’m wrong!

Humbling, isn’t it?

One response to “Why You Don’t Have To Check Every Nutty Claim

  1. Obviously all fundamentalist churches are the only one true church; now all of your clones will perish forever.

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