Mormonism

Confirmation Bias

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Confirmation bias is related to the tendency to say that all of the evidence is on my side. In particular it consists in attending to evidence that supports my position while ignoring contrary evidence, or interpreting the contrary evidence so that it appears to be supporting evidence. One way to resist this tendency is to notice that despite the saying, absence of evidence is in fact evidence of absence. If observing some evidence tomorrow would make your hypothesis more likely, then if tomorrow comes and you do not observe the evidence, your hypothesis becomes less likely. So if you can recognize the circumstances in which your hypothesis becomes more likely, you should be able to recognize the circumstances in which it becomes less likely.

For example, in the previous post, most people would recognize that (2) is evidence against (1), but recognizing this appears to be more difficult for Mormons. Nonetheless, if it had turned out that the Book of Abraham was in fact an accurate translation of an ancient Egyptian manuscript, this would have been evidence favoring Mormonism, and there can be no doubt that Mormons would have recognized it as such. Consequently, if they can recognize that this would have favored their position, they should be able to recognize that the actual fact (2) is evidence against it.

You cannot have it both ways. If you concede that getting what you ask for every time you pray to your guardian angel would be evidence for his existence, then not getting what you ask for is evidence against his existence. Of course such negative evidence is not necessarily very strong, and this may in fact be the point of the linked post.

The Evidence Does Not Change Sides

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Suppose someone holds the following position:

(1) Mormonism is the true religion.

Then he discovers this fact:

(2) Joseph Smith claimed to have translated the Book of Abraham from an Egyptian manuscript, but in reality the Egyptian manuscript was about something completely different.

Now this doesn’t look good. In fact, it looks exactly as though the Book of Abraham is a complete fraud, which seems to imply that position (1) is false. In other words, (2) is strong evidence against (1).

So our protagonist modifies his position like this:

3) Mormonism is the true religion, and Smith interpreted the Egyptian manuscript by divine inspiration, revealing its spiritual sense.

Now he notices something. After the discovery of fact (2), position (3) becomes more probable than it originally was, since part of position (3) is now verified to be definitely true, namely the fact that the book of Abraham is a not a literal translation of the Egyptian manuscript. Thus, the original disturbing fact which seemed to be evidence against his position, is now evidence in favor of his new position! And the new position includes position (1), so there is no need to change a thing!

This reasoning is technically valid, of course, but our protagonist is overlooking a few things.

First of all, (1) is in itself more probable than (3), since (3) requires the truth of (1) and something else in addition.

Second, after the discovery of (2), (1) becomes less probable, likely significantly less probable, than it was before. This fact remains unchanged by the rest of the process.

Third, (3) does indeed become more probable than it originally was, after the discovery of (2). However, (3) was less probable than (1) in the first place, and even after it becomes more probable, it remains less probable than (1) originally was, and it also remains less probable than (1) became after the discovery of (2). This is necessary because (3) is nothing but a particular way that (1) could be true. So by adopting the new position, our protagonist has not benefited by (2) in the way that he believes. Rather, he ends up holding a position that is even less probable than claiming that Mormonism is true, admitting that the Book of Abraham is not a valid translation of the Egyptian manuscript, admitting that this makes his original position regarding Mormonism less probable, and making no other changes.

In other words, the evidence does not change sides.

The Evidence is Not Automatically on Your Side

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One thing is evidence for a second thing if the second thing is more probable given the first, than the second without considering the first. Thus the fact that you are reading this blog post is evidence that you are a native English speaker, since someone reading the post is more likely to be a native English speaker than a random person is.

One common mistake is to think that there cannot be evidence for something false; but my position is true and the opposite is false; therefore there cannot be any evidence against my position. Thus people say things like, “Evolutionary belief is a remarkable and largely unexplained phenomenon. It is a belief held by most intellectuals all over the world, despite the fact that there is no real scientific evidence for it at all.” Again, someone holding another position says, “Critics of evolution claim that it is just a theory for which there is no proof. It is true there is no definitive proof, and nor is there likely to be, but there is a vast amount of evidence in its favour. Whether you choose to believe it is sufficient is up to you, but it is there. By contrast, there is no scientific evidence for creationism.”

The claim that your opponent’s position has no evidence for it is always false, without exception. For the very fact that your opponent holds the position is evidence for it, since a position that someone holds is more likely to be true than a random position that no one holds. But even apart from this, given any particular position that real people hold, we can expect to be able to find any number of facts that make more it more likely than it would be without those facts, even if the thing is absolutely false. Thus if you buy a lottery ticket, it is evidence that you will win the lottery, since it becomes more likely that you will win, having a ticket, than not having one. But ordinarily you won’t win anyway, despite your evidence for it.