Monday, September 13, 2010
Suppose Fred glances out the window and says: “The ground’s wet outside. It must have rained.” He’s given an argument. What should we think of it? We could say:
Oh dear, what a mediocrity poor Fred is. He is evidently arguing as follows: If it rains, the ground gets wet; the ground is wet; therefore it has rained. If he’d ever taken a logic class he’d know that he’s just committed the fallacy of affirming the consequent!
Yes, we could say that, but (to paraphrase Haldeman paraphrasing Nixon) it would be wrong. It is simply unreasonable and, indeed, unjust to accuse Fred of committing so blatant a fallacy when an alternative construal of his argument is easily available. For while Fred could have been reasoning deductively and committing the fallacy in question, it is more likely that he was reasoning inductively, along something like the following lines:
When the ground is wet outside, rain is the usual reason, though occasionally there are other reasons, such as flooding. The ground is wet outside right now and there is no reason to think these other causes are operative, and good reason to think they are not. So it is very likely that it has rained.
Obviously this is a perfectly respectable piece of probabilistic reasoning, and what logicians call the “principle of charity” requires that we assume that Fred had something like this in mind rather than the fallacious alternative interpretation, unless we have strong evidence to the contrary. If we fail to do so, we are guilty of the sort of illogicality of which we would accuse Fred.
Apropos of many commentators’ tendency glibly to accuse Aquinas of committing various blatant fallacies in the course of presenting his famous Five Ways, Christopher Martin once wrote:
As [Peter] Geach points out, if we wish to show that an argument is invalid, it is not sufficient to show that it can be represented as instantiating an invalid form. It might instantiate an invalid form and at the same time instantiate a valid form: and for an argument to be valid it is sufficient that it should instantiate a valid form. The potentially vast numbers of invalid forms which it may instantiate are completely irrelevant. As Geach goes on to point out: we can represent any valid argument as instantiating at least one invalid form. For there is nothing to stop us linking the premisses of any argument together with "ands" or other connectives, and representing the long sentence thus formed by the letter "p". Representing the conclusion of the argument by "q", we are thus able to represent any argument as a whole as instantiating the form "p, therefore q", which is about as invalid an argument form as one could wish to avoid, or to detect in the work of one’s rivals. (Thomas Aquinas: God and Explanations, pp. 161-2)
“Detecting” fallacies in the work of one’s rivals in this way is depressingly common, even among – indeed, perhaps especially among – people who have made a formal study of the logical fallacies. To be sure, on coming across a humdrum argument like Fred’s, those who have made such a study are unlikely to interpret it uncharitably. But where an argument is aimed at defending some proposition of a philosophical, theological, moral, or political nature with which they disagree, some are all too prone to put the worst possible spin on it.
Hence, when I taught critical thinking one election year, a number of my students expressed delight at how useful they found our look at the fallacies, as they had started seeing them committed frequently in political speeches. You can be sure that they were “seeing” them only in the speeches of candidates with whom they disagreed. And that’s the way the game is played: If your candidate utters a simplistic slogan, he’s committing the fallacy of appeal to emotion, or red herring, or false alternative; if my guy does it, well, haven’t you ever heard of the principle of charity? In fact, genuinely fallacious arguments are probably far less frequently given by politicians, either of the right or of the left, than is commonly thought. It does happen, of course, but in most cases what we really have are just arguments that are highly simplified so as to make them comprehensible to a mass audience in an age of sound bites, and which could be spelled out more fully and rigorously if need be (and indeed usually are spelled out by the economists, political scientists, and think-tank intellectuals from whom politicians and their advisers borrow their ideas).
To take just one example, arguments against “same-sex marriage” are often accused of committing the “slippery slope fallacy”—the fallacy of insisting that X will inevitably lead to Y, when in fact no necessary link between X and Y has been established. The conservative position is treated as if it were saying something like this:
If we allow people of the same sex to marry, then it will only be a few years before polygamy and incest are allowed, and after that the sky’s the limit – “marriages” between people and animals, living people and corpses, and who knows what else!
Such an argument is then dismissed as paranoid and unfounded, since obviously a person who favors “same-sex marriage” might happen to oppose these other things. But in fact, that is not the conservative argument at all. Opponents of “same-sex marriage,” or at least the more sophisticated opponents, are not giving a slippery slope argument, but rather a reductio ad absurdum argument. They are saying something like this:
Defenders of “same-sex marriage” claim that what really matters in a marriage is just that the partners are lovingly committed to one another. They also claim that marriage is conventional and not grounded in the natural order of things, so that it is up to us to decide what marriage is about in light of changing standards. But given the first premise, there is no way they can consistently rule out the legitimacy of polygamous marriages or incestuous marriages; and given their second premise, there is also no way they can insist in principle on their “loving commitment” criterion for marriage in a way that would rule out “marriages” between people and animals, living people and corpses, or indeed anything whatsoever that someone might want to call “marriage.” For someone could always argue that even the “loving commitment” criterion is as arbitrary and open to challenge as the heterosexual criterion is. Yet defenders of “same-sex marriage” also claim that they are opposed to these other purported forms of “marriage.” Therefore, their position is incoherent.
Defenders of “same-sex marriage” might try to respond to this sort of argument in various ways, but they cannot reasonably accuse it of being blatantly fallacious, since reductio ad absurdum is, of course, a perfectly respectable form of argument. (Of course, a conservative who puts forward this argument might also claim that “same-sex marriage” will in practice lead to these other purported forms of “marriage” as well. But even in that case he would not be committing a slippery slope fallacy, for the reductio argument gives a reason for thinking that “same-sex marriage” will tend to lead to the other things.)
Professional philosophers are by no means immune to this tendency to give the arguments of their opponents the worst possible reading. As I have often complained, certain atheist philosophers ritualistically present the cosmological argument for the existence of God as if it went like this: Everything has a cause; so the universe has a cause, namely God. After raising the obvious objections (“If everything has a cause, then what caused God?” etc.), they then treat even the most sophisticated defenses of the cosmological argument as if they were desperate attempts to patch up this transparently feeble line of reasoning. But as I noted in several earlier posts (here, here, and here), none of the major philosophers who have defended the cosmological argument – not Plato, not Aristotle, not al-Ghazali, not Maimonides, not Thomas Aquinas, not John Duns Scotus, not G.W. Leibniz, not Samuel Clarke, not Reginald Garrigou-Lagrange, not Mortimer Adler, not William Lane Craig, not Richard Swinburne, and not anyone else as far as I know – ever put forward this silly argument. It is the philosophical equivalent of an urban legend – an argument that “everyone knows” has been defended for centuries, which in fact has never been defended. And yet such ludicrous caricatures are frequently put forward as “evidence” of how lame the traditional arguments for God’s existence are, and used as an excuse for not bothering even to read work done in the philosophy of religion. (“If the main arguments are that bad, what’s the point?”)
In this way, the study of logic becomes precisely the opposite of what it is supposed to be – a rhetorical gimmick, a cudgel with which to beat opponents and advance agendas rather than an aid to the disinterested pursuit of truth. In the name of attacking sophistry and fallacy, a higher-order sophistry – a “meta-sophistry,” if you will – is perpetrated.