One after the other the men rise, defiantly shouting, “I am Spartacus!”
Crassus, who knows his logic, realizes that because each man claimed to be the one true Spartacus, there could be no one true Spartacus, and so he released them all in the names of Diversity, Tolerance, and Rationality.
Kidding! I’m kidding.
Because Crassus knew (from the evidence of the war) there had to be one true Spartacus, he crucified everyone. Ouch. Based on subtle behavioral clues, he most suspected two of the men. He saved this pair for last and had them fight to the death. The one true Spartacus mercifully killed his lieutenant and was then himself crucified. Crassus never knew for certain he had his man—and to add to the subtlety, the one true Spartacus never shouted “I am Spartacus!”—but reasoned that, given the evidence he had, he made the best choice.
Which he did. Make the best choice, I mean.
If Crassus reasoned as we first supposed, by saying that because every man claimed to be the one true Spartacus there could not therefore be a one true Spartacus, he would have committed the One-True-Religion fallacy. This fallacy says because there is a choice or there is disagreement, there can be no right answer.
Stated so simply, it’s obviously silly and you might figure nobody would ever wield such a limp noodle. Wrong, naturally.
The One-True-Religion fallacy is particularly beloved of new atheists who use it to deny that all other religions except theirs is false, which is a sort of two-for-one solecism. First comes the OTRF then the denial that their religion is one, the latter error likely arising from the false belief that religions must have nameable gods.
Regardless whether I’m right about that, it is certain the OTRF for the new atheist plays the same role as “Peer review!” (the Peer Review fallacy; coming soon) does for foamy-mouthed global warming apocalypse fanatics. The new atheist’s favorite joke is to list minor deities in whom they disbelieve and then to quip that they “reject” one more deity than the traditional theist, which is God. As a plain statement of observation, this is not problematic, but if it is used, as it almost always is used, to imply that the one more deity (God) does not therefore exist, it is the OTR fallacy.
Here (use your imagination) are two theists of different religions and an atheist. Theist One says, “My religion is the one true religion.” Theist Two says, “No, my religion is the one true religion.” The atheist says, “What loons. All religions claim to the one true religion. Therefore there is no one true religion.” Given just the information available, the atheist has committed the OTR fallacy and at least one of the theists has made an error—but we cannot say that both have.
Theists fall into error as often as atheists. Usually this is because of humility coupled with justified uncertainty, which are no bad things, or perhaps a too liberal interpretation of ecumenicism, which is. The polite theist resists claiming his religion is the one true religion, even though he believes it is, in an effort to spare the feelings of his audience, perhaps hoping to win his listeners over with coyness. The danger is that this practice becomes habitual and the theist forgets what he believed.
The OTRF isn’t limited to religion. For example, I believe it is true that the only sensible and correct interpretation of probability is logical (as a branch of logic). Bluntly, I claim probability-as-logic is the one true interpretation. From this follows the conclusion that all other interpretations are wrong. I may (and do) allow, as theists allow of rival religions, that other interpretations have their good points; but taken strictly, they are false.
I might be wrong about this, of course. But it is no criticism and a clear instance of the OTR fallacy to argue that “One shouldn’t be dogmatic in philosophy or science,” (as Ian Hacking on this subject argues), or “We should be pragmatic in our understanding of probability theory,” or “What conceit to suppose one knows the one true theory!” Conceit it may be, but neither my mood nor my critics’ has probative value on the truth of the theory.
The OTR fallacy is always invoked when a critic can’t be bothered to do the hard work of refuting a claim. Refutation is hard labor. Scorn is easy and free. And to the believer I say, the time for humility is in the face of uncertainty. Where there is certainty, plain speaking is best.
I would thou wert cold or hot. So then because thou art lukewarm, and neither cold nor hot, I will spue thee out of my mouth.