Logicians routinely distinguish between necessary and sufficient conditions. If X is a necessary condition for Y, then wherever there is Y there is also X; but the reverse may not be true (there may be X without Y). If X is a sufficient condition for Y, then wherever there is X there is also Y; but the reverse may not be true (there may be Y without X). Clearly it’s important to distinguish necessary conditions and sufficient conditions, since the one does not imply the other, and failure to distinguish them leads to fallacious inferences.
In a previous post, I remarked that Richard Dawkins’ book The God Delusion is a rich source of examples of logical fallacies. I pointed out a rather blatant instance of petitio principii (begging the question) in chapter 3. It seems to me, however, that the prolific professor doesn’t even make it past the first page of the book without committing an error in reasoning.
One of the first thoughts Dawkins introduces in the book’s preface is the notion of a conspicuous link between religion and acts of evil in the world. He mentions the television documentary he presented in 2006, entitled “Root of All Evil?”, but quickly points out that he wasn’t happy with its title.
Religion is not the root of all evil, for no one thing is the root of all anything. (p. 1)
Dawkins sensibly disavows the idea that religion is a necessary condition of evil; that wherever there is evil there is also religion. So if the relationship of religion to acts of evil is not that of necessary condition, what is it? One can’t help but get the strong impression from The God Delusion (not to mention his other writings) that Dawkins takes the relationship to be that of sufficient condition, or at least very close to that. Wherever there is religion there is also evil — nearly always, if not always. (This is the man, after all, who declared that religion is a “virus of the mind”.) So the idea Dawkins apparently means to endorse is that religion is (typically) a sufficient condition for evil — whether in thought, or in word, or in deed.
What’s remarkable therefore is what immediately follows in the preface:
Imagine, with John Lennon, a world with no religion. Imagine no suicide bombers, no 9/11, no 7/7, no Crusades, no witch-hunts, no Gunpowder Plot, no Indian partition, no Israeli/Palestinian wars, no Serb/Croat/Muslim massacres, no persecution of Jews as ‘Christ-killers’, no Northern Ireland ‘troubles’, no ‘honour killings’, no shiny-suited bouffant-haired televangelists fleecing gullible people of their money (‘God wants you to give till it hurts’). Imagine no Taliban to blow up ancient statues, no public beheadings of blasphemers, no flogging of female skin for the crime of showing an inch of it. (pp. 1-2)
One has to admit, the internal logic of this paragraph is impeccable. If this had been a world with no religion, surely none of these evils would have existed. Evidently Dawkins wants us to observe a connection between religion and these acts of evil. But what is that connection?
It ought to be obvious that the connection here is that of necessary condition. If X is a necessary condition for Y, then there will be no Y without X. (Just replace X with ‘religion’ and Y with any of the evils catalogued in the quoted text.) But of course, to point out that religion was necessary for those particular evils is not at all to show that religion was sufficient for those particular evils, let alone sufficient for evil in general. (Nor does it show that religion is necessary for evil in general, a claim that Dawkins explicitly rejects.)
In other words, it’s hard to see the relevance of this observation to the sort of general claim Dawkins wants to defend. After all, there are many necessary conditions for the particular evils in Dawkins’ list. Try replacing the word ‘religion’ in the quoted paragraph with ‘humans’, ‘consciousness’, ‘oxygen’, or ‘strong nuclear force’. In each case the logical connection is the same; and in each case the conclusion is just as irrelevant.
So what’s the moral of the story? Don’t try to establish a sufficient condition by appealing to examples of a necessary condition.
Footnote: One might object that in the quoted paragraph Dawkins is actually offering his readers an inductive inference to support his claim about the connection between religion and evil. I think there are two reasons why this defence won’t cut it; but I’ll leave those for a future post.