Discussion Grounds

Tom,

I think that when I talk about werewolf-theory and about Jesus performing “party tricks” you may think I am disrespecting you. If you could hear me say these things face to face I think you would not feel disrespected, by my tone of voice is not communicated clearly via a text medium.

So allow me to reinforce what I said about werewolf theory and Jesus performing party tricks, as examples. I do not mean these to be flippant, dismissive remarks. I mean them very specifically and literally. I literally think a theory of werewolfism could contain less implausible and less ad-hoc hypotheses than Christianity does. And Jesus literally performed party tricks: turning water into wine at a wedding. So I mean that all quite literally, not flippantly.

I’m doing the same thing when I tell people my deconversion story and I recall the moment when I realized I literally believed I had an invisible magical friend who granted me wishes. I believed Jesus was my friend, I believed he was invisible, I believed he had magic powers (aka “supernatural” powers), and I believed he sometimes fulfilled telepathic wishes I made (prayers). When telling this story I do not mean that statement flippantly or dismissively, either. I mean it very specifically and literally.

And of course it’s possible that I really did have an invisible magical friend who granted me wishes. When I realized this I did not give up my faith. I had many reasons to believe it was true. It was only after these reasons were undermined by argument and evidence that I had to admit it was not true that I had an invisible magical friend who granted me wishes.

With that in mind, let me reaffirm the respect I have for you. Tom, you’re a smart guy. A loving guy. A genuine seeker of truth. I don’t think you’re being willfully dishonest (like some apologists are). And I respect that. I think it’s literally true that a common conception of Jesus is that of an invisible friend who sometimes grants wishes, and I think it’s literally true werewolfism could be less implausible and less ad-hoc than Christianity, but none of that means I disrespect you. It just means I think you’re wrong, for very specific reasons.

Okay, back to the main topic.

We’re at the point again where we need to find some common ground before we can continue. Before I say anything more about whether Christianity or naturalism offers a superior explanation for the human condition, we should get clear on what we think a good explanation is.

You gave three criteria for a good explanation:

(A) by knowing x we understand y better than by not knowing x; and if

(B) there is adequate reason to believe that x is true, reliable, trustworthy, etc.; and if

(C) there is no competing z, such that z is contrary or contradictory to x and fulfills the conditions of (A) and (B) more successfully than does x.

But I’m not sure how this can work. Saying that theory x is a good explanation for y is precisely what gives us reason to believe that x is true (as I understand explanation). So to put (B) in the requirements for a good explanation just sets us back to the starting point. We are left asking, “Well, is that x a good explanation of y, so that we have good reason to believe x is true?”

When you say that e is evidence for x, what you’re saying is that x provides the best explanation for e. Otherwise, e could just as well be evidence for the Zeus theory of lightning as for the electric theory of lightning. The reason e is evidence for the electric theory of lightning instead of being evidence for the Zeus theory of lightning is that the electric theory is a better explanation of e. (And it is a “better” explanation of e in that it has better explanatory scope, explanatory power, and so on – compared to the Zeus theory. See below.)

At least, that’s what I mean when I use these terms. But they are used in varying ways, and that’s probably why we need this cleared up.

So how do we tell which hypothesis (or theory, a collection of hypotheses) is the best explanation of some phenomenon (say, “the human condition”)? Some prefer the approach of Bayesian confirmation theory, such that the best explanation is one who final probability is greater than 0.5. One non-fatal difficulty with this approach is that we cannot assign accurate probability numbers to the terms of the equation. Another is that it seems to set the bar too high. Scientific theories are often accepted before we have reason to believe their probability is greater than 0.5.

One alternative view to confirmation theory is “explanationism.” The explanationist may accept a theory whose probability does not exceed 0.5. Instead, the explanationist may merely require that a theory possess certain explanatory virtues to a greater degree than competing theories.

Scientists and philosophers have developed an indefinite but useful set of explanatory virtues. The list looks something like this:

1. Testability – a good explanatory hypothesis should be testable.
2. Consistency with background knowledge – a good explanatory hypothesis should not contradict our background knowledge.
3. Past explanatory success – a good explanatory hypothesis should fit in a tradition with much past explanatory success.
4. Simplicity – a good explanatory hypothesis should be simple, not making a lot of ad-hoc assumptions.
5. Ontological simplicity – a good explanatory hypothesis should not add more unknown things to our ontology than necessary.
6. Informativeness – a good explanatory hypothesis should allow us to deduce precise details of its effects.

Of course, there are other virtues we might consider. I could also spend time arguing why these explanatory virtues, if fulfilled by explanation x, argue in favor of x being the correct explanation. But I suspect we agree on several or all of these explanatory virtues already, and I have said enough for one post.

So, Tom, are we any closer to a common understanding of what a “good explanation” is?

Your turn!

Luke