An Example of High vs. Low Probability

Yesterday, at 3pm, I was in Fort Worth.

Do you believe me? Probably.

But how do you know that I was in Fort Worth? I mean, I could have been in Houston. Or Timbuktu. Or Norway (which, actually, I would prefer).

So you don’t know, the argument goes. But there’s a high probability, you might say, that I’m telling the truth. Being in Fort Worth is not at all unusual, and there is no reason to believe I’m not there, so you’re probably willing to just take my word for it.

That focus on probability is a good thing when I say something like:

Yesterday, at 5pm, I was on the first manned spacecraft that was headed to Mars.

As long as we’re talking about probabilities, you have a rationale for rejecting that claim. Yes, it’s the same evidence as the first claim, but it has a lower probability of being true. So when I say, “Why do you believe the first claim and not the second when they both have the same evidence?” You can say, “Well, there’s a lower probability that you were headed for Mars than that you were in Fort Worth, and I need more evidence for claims that have a lower probability rate.”

I guess I could challenge you on the exact numerical probability of my being on a spacecraft headed to Mars vs. the exact numerical probability of my being in Fort Worth and think that your inability to come up with an exact number was a sticking point. But that’s not really necessary, is it? I don’t have to know exactly how probable each possibility is in order to say that, clearly, it’s more probable that I was in Fort Worth yesterday than that I was on the first manned spacecraft headed to Mars.

Gravy?

Now, let’s change the scenario.

How the Concept of Faith Introduces a Glitch

I say: Yesterday, at 3pm, I was in Fort Worth.

Do you believe me? Probably.

But do you know that I was in Fort Worth? For all you know, I could have been in Houston. Or Timbuktu. Or Norway (which, actually, I would prefer).

So you don’t know, the argument goes. Same as before up to this point. But here, instead of discussing probability, I use the word “faith.” I say, “So you have faith that I was in Fort Worth.”

And with that slight of hand, I’ve thrown a monkey wrench into the entire conversation. Because “faith” has become a word that is used to make all probabilities undifferentiated from each other and thus the same. You can’t say something has low probability or high probability any more — all you have to describe probability, if you agree with my terminology, is the word “faith.”

So, when I say, “Yesterday, at 5pm, I was on the first manned spacecraft that was headed to Mars,” you are kinda stuck in trying to explain why you reject that claim. You had faith that I was in Fort Worth, I may challenge. So why can’t you have faith that I was on the first manned spacecraft that was headed to Mars?

You might rebut that there is not enough evidence that I was headed to Mars, and I’ll simply answer that there was just as much evidence given for my being headed to Mars as there was for my being in Fort Worth — I told you the first, that was all the evidence you really had, and you believed me; and then I told you the second, that was all the evidence you really had, and you didn’t believe me. Why was there enough evidence for you to have faith in the first proposition and not have faith in the second? It’s all faith, I might go on. The person who believes me and the person who doesn’t believe me both have faith. So if you don’t believe me in the second scenario when I’ve given the same evidence for each scenario, your choice must be based on preference instead of logic.

Once I say that your choice of faith is due to preference instead of logic, I can start psychoanalyzing you, saying that you don’t believe I was on the first manned spacecraft headed to Mars because you didn’t want me to be on the first manned spacecraft headed to Mars due to jealousy or something, and that could be all she wrote (kinda like Christians say that you don’t believe in God simply because you don’t want Him to exist). Especially if I ask you if you’d be jealous if I were headed to Mars and you weren’t, and you said, “Yes.”

Hopefully all that makes sense, because now I’m gonna apply it to the main point of this post.

How the Glitch is Exploited in Religious Apologetics

The truth is, you’re never really 100% sure about anything (yes, even this last sentence).

What we do is look at how the world seems to work and apply various probabilities to certain possibilities. And when the probability seems high that something is true, then we’re more likely to go with the assumption that it is true when a bit of evidence is presented to us.

And this comes out in everyday speech. There is always, it seems, a bit of skepticism when we discuss things. Like the Fort Worth example — after I claim to be in Fort Worth, you’ll probably say, “Peter is in Fort Worth” as opposed to “Peter is probably in Fort Worth” because of the high degree of probability that the former is true. But we both know that it’s possible I’m not actually there.

The same goes with, like, everything. It’s how we talk and operate in the world. We depend on the ability to assign different probabilities to possibilities in order to make everyday decisions and survive. A glitch of religion — a major reason that religious people can believe the fantastic things in the Bible — is that the ability to assign different probabilities to extraordinary things in the Bible is hijacked by the concept of “faith.” For example, people think that the fact that there are thousands of copies of the Bible (although most were made after the Roman Empire became Christian and began churning them out) makes the resurrection true, because copies of Plato are less numerous and have a much greater temporal distance from the originals, and yet we believe that Socrates committed suicide. We have faith in the latter, the statement goes, so we should have faith in the former.

Now, the problems with that argument go beyond what I’m about to say, but the biggest one is that it ignores the issue of probability. We have little reason to doubt that Plato existed. We have all the reason in the world to doubt that a resurrection of a godman happened after he was stone-cold dead three days in a tomb — a claim that seems much more improbable than the claim that yesterday at 5pm I was on a spaceship headed to Mars (we’ve never even come close to seeing a man raised from the dead after three days of stone cold death, ever, but, um…we’ve actually sent spacecrafts to Mars).

But you can’t make that argument if you replace “probability” in your vocabulary with “faith.” The switch in vocabulary diminishes the ability to differentiate between likely events and unlikely events in your evaluation of evidence.

So…in future conversations with Christians on religion, a handy tip is to encourage a focus on “probability” as opposed to “faith.” It doesn’t end the conversation, to be sure — but if my experience is any indication, it certainly may help you make more progress.

Thanks for reading.