Marrten Boudry claims that there are far fewer fallacies out there than we think. His reason involves a 'fallacy fork.' The fallacy fork is a dilemma the conclusion of which is supposed to show us that fallacies are not usually fallacies. Here is the fork:
Either the fallacy is hardly ever used, or it is hardly ever fallacious.
For a fallacy to count, it must imply some deductive form. Since, we hardly ever make deductive arguments that are candidates for fallacies, we should prefer the second fork. So, are what we call fallacies not really fallacies after all?
Consider, the ad hominem fallacy. A candidate for office claims that policy x will make everyone safer. Her claim is rejected on the grounds that she has known terrorists as personal friends. On the face of it, the claim could not be decided merely on the grounds of the friendships of the one who makes the claim. The assumption one has to make is something like, "anyone with terrorists as friends should not be trusted when making a suggestion about what will make us safer."
Whether or not a fallacy has been commited might depend on all sorts of contextual factors. Say, for example, the friendships are with the very terrorists from which the candidate is claiming to keep us safe. In this case, the reasoning is not suspect. If, however, the candidate is suggesting a water filtration system to make water cleaner (and is attempting to keep us safe from unclean water), then her friendships with terrorists is less relevant.
Boudry suggest that fallacious reasoning can only be determined given a multitude of contextual factors and they are far less common than freshmen taking a critical reasoning class think.
So, contexts determine whether a fallacy has been commited. But what are those contexts? One plausible context is the worldview held by the claimant and the fallacy accuser. Consider one of Boudry's suggestions taken from Carl Sagan's The Demon-Haunted World. Sagan suggests the following as an example of ad hominem reasoning:
“The Reverend Dr. Smith is a known Biblical fundamentalist, so her objections to evolution need not be taken seriously” (Sagan 1996, 212).
The authors claim that no fallacy has been committed:
...unless Sagan’s argument is meant to be deductive (first prong), it is not fallacious at all (second prong). If we know that the good Reverend is an evangelical Christian, who dogmatically clings to a literal reading of Scripture, of course this will color our judgment about her arguments against evolutionary theory. I’d go even further: pragmatically speaking, this fact alone is reason enough to dismiss her arguments, and not to waste any further time on it. It’s simply naïve to think we have an obligation to scrutinize the arguments of every single crank. In an ideal world perhaps, with unlimited time on your hands, but not in this one. So ad hominem arguments are indispensable for navigating our way through a social world.
The context in question appears to be the worldview of the evangelical Christian, "who dogmatically clings to a literal reading of scripture." Such a view of scripture colors the judgment of the creationist and renders his claim a waste of time. But what is thought to be a context of an ad hominem is actually a factor that removes the argument from the candidacy of being an ad hominem. To see this consider the ad hominem spelled out in full:
- X claims that evolution is false
- X believes the Bible is literally true
- Anyone who claims the Bible is literally true is not trustworthy
- Therefore, we should not take the claim that 'evolution is false' seriously.
3. Anyone who claims the Bible is literally true is not trustworthy
3'. The Bible is not literally true
Once one does this, there is no ad hominem premise. Instead, we merely have a rejection of one or other belief that the claimant holds.
What the authors say next is that a creationist might make a claim about evolution that does not rely on a religious belief about the Bible but on some scientific grounds:
None of this is to deny that, logically speaking, even a die-hard creationist could conceivably level a good argument against evolutionary theory. If you think that the Reverend’s argument must be wrong, given her evangelical faith, you are making an error of deductive logic. But let’s be honest: if some Jehovah’s Witnesses hand you a pamphlet with “scientific” arguments against Darwin, are you going to give them your full attention, lest you succumb to ad hominem reasoning?
What's strange about this response is that on the one hand it admits that a creationist could have a good argument against evolution, but, on the other hand, suggests that it would be reasonable to reject it because of the religious worldview the creationist holds. The authors clearly commit an ad hominem at this point: even if the creationist offers a good non-religous argument for her claim, her claim should be dismissed solely on the grounds of her being religious!