Is HADD Evidence Against Theism? Part 1

I’ve been thinking lately about whether HADD, on the assumption that it exists, is evidence for or against the existence of God. I’m starting to think it is neutral, but I’m posting this here for feedback.


Before diving into the details, let’s review a few items for context.

First, let’s address terminology. HADD is an acronym which stands for “Hypersensitive Agency Detection Device.” HADD is a theory in the cognitive science of religion which says that most humans seem to be hard-wired to believe that agents explain various facts; this tendency seems to include all sorts of invisible agents, including God, gods, ghosts, and so forth.

N stands for naturalism; T stands for theism; and I’m continuing to use the same definitions I’ve offered before.

Second, I’ve written before about the structure of explanatory arguments. I’m going to adopt that same argument structure here. So, let’s dub the following argument “the evidential argument from HADD” against theism.

The Evidential Argument from HADD Formulated

(1) HADD is known to be true, i.e., Pr(HADD) is close to 1.

(2) T is not intrinsically much more probable than N, i.e., Pr(T | B) is not much more probable than Pr(N | B).

(3) Pr(HADD | N) > Pr(HADD | T).

(4) Other evidence held equal, T is probably false, i.e., Pr(T | B & HADD) < 0.5.

The Evidential Argument from HADD Assessed

For purposes of this post, I’m going to assume that both (1) and (2) are true. If (1), (2), and (3) are true, then (4) is necessarily true. So what I want to do is figure out if there are any good reasons for thinking that (3) is true. Are there?

The “HADD Produces Many False Positives” Argument

Here’s one reason to think (3) is true, what I call the “HADD Produces Many False Positives” argument. This argument focuses on the letter “H” in the acronym HADD: most humans not only have a mental tool called an “agency detection device” (ADD), but this device is literally hypersensitive. Given ambiguous information, most human brains have a tendency to err on the side of assuming that an agent–maybe even an unseen or invisible agent–is responsible for the ambiguous information. This mental tool has survival value because it causes people to be on guard against potential predators. Furthermore, it’s better for ADD to err on the side of false positives than on the side of false negatives. So because HADD generates so many false positives, it is unreliable. On the assumption that naturalism is true (and humans are the result of unguided evolution), this is just what we would expect. If naturalism is true, nature is “blind” and so is indifferent to our beliefs about a non-existent God. On the assumption that theism is true, however, there is much more to reality than just “blind nature.” God not only exists, but cares about human beings such that God would not rely upon an unreliable process like HADD to produce theistic belief.

One reason to doubt this argument has to do with HADD’s reliability in the context of religious beliefs. First, it may be the case that HADD is notoriously unreliable in some contexts (such as hearing strange noises at night), but very reliable in other contexts (such as religious beliefs). Second, it’s doubtful that HADD is the only mental tool involved in the formation of religious beliefs. So what is the reliability of HADD when combined with these other mental tools? In order for the “HADD Produces Many False Positives” argument to work, it seems to me that we would need some way to show that the combination of HADD and other mental tools often leads to false positives about supernatural agents.