A simple response to the normalizability objection to the fine-tuning argument

The normalizability objection isn't necessarily an argument against fine-tuning. Rather, it's an argument against the idea that we can quantify fine-tuning or attach a specific probability to it. There are some people who think you need to be able to attach a number to a probability before probability makes any sense, but I want to challenge that idea.

Let's say you're standing in front of a wooden fence. As far as you can see to the left and to the right, the fence kind of disappears over a hill, through the trees, or maybe even out to the horizon. You don't know how far it goes beyond that point. As far as you can see in either direction, the fence is red. But there is one board right in front of you that's blue. You may have no idea how far the fence goes in either direction, but you can still see that the blue part is relatively tiny in comparison to the part you can see. Since you can't tell how far the fence goes, you can't normalize the probability that throwing a dart from any random location will result in sticking in the blue part rather than the red. But that doesn't prevent you from noticing that there's a lot more red than blue, and your dart is far more likely to hit the red part than the blue.

In the same way, you can tell that the life-permitting range is much smaller than the possible range of values to the fundamental constants and initial conditions of the universe. You can tell that changing the values by a small amount will result in a life-prohibiting universe without having to know the full range of possible values. So you don't need to know precisely how fine-tuned the universe is to know that it's fine-tuned.

I think this is what Robin Collins was getting at in his chapter in the Blackwell Companion to Natural Theology.

One counter-argument that could be raised to my analogy is that for all we know, the fence becomes blue over the horizon. Maybe it's blue from there on out, which means there could be far more blue than red. We just wouldn't know. If the blue represents the life-permitting range, then we'd have to say that maybe at some arbitrarily large or small value to some constant, the universe becomes life-permitting again.

Although it's possible, for all I know, that there could be islands of habitibility in the parameter space of all the constants, it strikes me as being unlikely that these islands would be very big if they exist at all. If we just limit ourselves to the known laws of physics and our ability to model, calculate, and simulate universes, as far as we are able to see, there are no remote pockets of habitility. If you just keep increasing or decreasing the value of some constant beyond the life-permitting range, the problem for habitility appears to only get worse. We can tell that without having to take it out to infinity. But admittedly, I don't know the physics well enough to press that point too hard.

For more thoughts on the normalizability objection see "The noramlizability objection to fine tuning, take one."