entail that we do not, on the basis of the available evidence, have excellent grounds for believing there's no cat present.
Might such an empirical, if not properly scientific, refutation of certain supernatural claims be possible? Again, I don't see why not. Suppose Mary claims she has a supernaturally aided ability to predict the toss of a coin. She says an angel whispers into her ear whether the next toss will be heads or tails. Because Mary's claim concerns the supernatural—concerns what is behind the veil dividing the natural from the supernatural realm—does that entail that the claim is not amenable to empirical investigation and refutation? Obviously not. Mary's supposed angel may be on the other side of the veil. But its activities, if real, have consequences that can be observed on this side. If there really is an angel whispering in Mary's ear, Mary will able to predict correctly the next ten tosses of the coin. If she fails to predict all ten tosses correctly, it's reasonable for us to conclude that Mary is either lying or deluded. While not terribly “scientific,” this would constitute a straightforward and effective refutation of a supernatural claim.
What about belief in God? Might that also be open to an empirically based, if not properly scientific, refutation? Again, I can't see why not. In fact, as we saw in my introduction (appendix B), the evidential problem of evil does appear to constitute just such a refutation. If there really is such a maximally benevolent and powerful being, then surely, while the universe might contain some pain and suffering and moral evil, it wouldn't contain anything like the amounts we observe. It certainly wouldn't contain any gratuitous suffering. But surely there is so much suffering, including nonhuman suffering, that it's implausible that it can all be explained as the unavoidable price paid for certain greater goods. Notice this argument is obviously empirically based —it relies on our observation of the world and the vast quantities of suffering it contains. Science might make a contribution toward the argument's effectiveness, of course, byrevealing, for example, that the suffering we observe has also been going on for hundreds of millions of years (that's a properly scientific discovery). But the evidential problem of evil is not ordinarily classed as a “scientific” argument, despite being empirically based. It's a common or garden-variety type empirical refutation. Which is not, of course, to diminish its effectiveness.
To sum up, even if we cannot, strictly speaking, provide a scientific refutation of belief in God, it does not follow that we cannot refute belief in God. I'd suggest that anyone who supposes that only science is capable of refuting god beliefs is seriously underestimating what other approaches—including more philosophical or conceptual approaches—might be capable of.
SCIENCE AND THE SUPERNATURAL
Let's now turn to the suggestion that no scientific refutation of a supernatural claim is possible. I see no reason to accept this.
Samantha's Supernaturally Empowered Spit
Consider a hypothetical case. Suppose Samantha claims her saliva has miraculous healing powers. She supposes that if she rubs her saliva over wounds, skin complaints, diseased organs, and so on, this has a miraculous curative effect. Samantha's friends and relatives swear to the amazing restorative powers of her spit. Samantha doesn't know exactly how it works, but she does claim to know that it has something to do with the spirit realm. By some supernatural means, people are cured.
Does that fact that Samantha's claims that her spit has some sort of supernatural power—that the cures it produces are of a supernatural origin—mean that her claims are not scientifically refutable? Obviously not. It's not difficult to think up some properly scientific tests. For example, suppose we provide Samantha with three vials, one of her own saliva, one of a stranger's, andone