Thursday, May 19, 2005

Favorite fallacies-1

Although Triablogue is into more than apologetics, the defense of the faith once delivered is a major focal point. It is striking how many fallacies crop up with such frequency in theological debate, both between fellow believers as well as between believers and unbelievers.

In one sense this is not surprising, for if two people disagree, then one or both are wrong, in which case fallacious reasoning figured in the error.

Some fallacies are a result of careless reasoning or lack of mental discipline. Yet men often make the most elementary blunders in reasoning. This is more often due, not to lack of subtlety, but incentive. The impediment is moral rather than intellectual.

We see this all the time in politics, where a partisan will not give the opposing side a fair hearing, where he will willfully and maliciously misrepresent the opposing position, even after he’s been corrected.

Calvin described his Christian conversion in interesting terms. He didn’t say that his heart felt strangely warmed, like Wesley. He didn’t say that he made a decision for Christ, or invited Christ into his heart. Instead, he said that the Lord had made him teachable. A teachable spirit is a mark of a true believer.

I’d add that a sophisticated command of logic is no silver bullet. Run through a list of the great logicians, and they span the philosophical spectrum. But in the right hands, it does guard us against elementary mistakes which may figure in elemental beliefs.

When is a fallacy a fallacy? Some so-called fallacies are not necessarily fallacious. Distinctions must be drawn, and different situations taken into account.

Some Christians feel that there is something unspiritual about logic, yet Bible not only authorizes the principle of logical inference but also obligates its use. Let’s run through some examples. In his dialogue with the Devil (Mt 4:6-7), Jesus takes Deut 6:16 as a paradigm passage which exerts hermeneutical control over Ps 91:11-12. He reproves the Sadducees for their failure to see the relevance of Exod 3:6 to the afterlife (Mt 22:32). Gen 1:17 & 2:24 are taken as paradigm passages which serve as a check on the divorce provision in the Mosaic Law (Mt 19:4-9). In what appears to be an a fortiori argument, Christ’s use of a divine designation in the proper sense is justified by appeal to its use in the titular sense (Jn 10:34; cf. Ps 82:6). In defending his activity on the Sabbath, he employs a variety of argumentative strategies: argument from analogy (Jn 5:17; 7:23); a fortiori argument (Mt 12:5-6,12; Lk 13:15-16); hallowed example (Mt 12:3) principle over process (Mt 12:7); and relative rationale (Mk 2:27). Sometimes he poses a dilemma (Mt 21:24ff.; 22:45), while at other times he denies his opponents’ premise (Mt 19:8ff.; 22:29ff.).

Peter and Paul both derive the Messianic application of a Davidic Psalm from its inapplicability to David proper (Acts 2:25ff.; 13:13f.; cf. Ps 16:8ff.). By parity of reasoning, Peter arrives at the same interpretation of another Davidic Psalm (Acts 2:23; cf. Ps 110:1). Stephen deduces his “pilgrim theology” on the basis of relative chronology and geography (Acts 7). In proving sola fide , Paul employs a variety of argumentative strategies: by direct prooftexting (Gal 3:11; cf. Hab 2:4); by inference from election (Rom 8:34), or from the contrary consequence (Gal 3:10; cf. Deut 27:27); or from the converse implication of non-imputation (Rom 4:6ffl.; Ps 32:1-2); and on the basis of relative chronology (Rom 4:10ff.; Gal 3:17; cf. Gen 15:6). He infers mortification from union with Christ (Rom 6:1); assurance from special redemption (Rom 8:32,34); unconditional election from prenatal chronology (Rom 8:11; cf. Gen 25:23), and from the principle of soli deo gloria (Eph 2:9); as well as eschatological deliverance from justification (Rom 5:9-10). Joel 2:32 generates a chain of inferences consisting of four interconnected links (Rom 10:14-15). He also reasons from analogy (1 Cor 9:9; 1 Tim 5:18).
The author of Hebrews goes so far as to draw inferences from the very silence of Scripture (1:5,13; 7:3,14). He also draws counterfactual inferences (4:8; 7:11; 8:4,7; 10:2; 11:15). He is a master of the a fortiori argument (2:2f.; 7:7; 8:6; 9:13f.; 10:28; 12:25). He will exploit the incidental connotation of a modest qualifier (12:27). In order to establish the superiority of the New Covenant he employs a variety of argumentative strategies by drawing inferences from typology (10:2); the Resurrection (7:24), the new priesthood (7:12); and the divine oath (7:22).


An argument from authority is not necessarily fallacious. It can be fallacious if your opponent does not acknowledge the authority, or if the “authority” in question doesn’t know what he’s talking about.

In order to avoid a fallacious appeal, the disputant may need to offer a supporting argument for his authority source.

There are also cases in which the disputant doesn’t have to offer a supporting argument even if his opponent fails to acknowledge the authority in question. That would be in the event that it is unreasonable of the opponent not to acknowledge the authority in question.

For example, if you quote Bruce Metzger against a Jehovah’s Witness on the rendering of Jn 1:1, the burden of disproof is on the Jehovah’s Witness.

It can also be fallacious to argue from authority if the experts disagree. It is, for example, fallacious for a Darwinist to say that no serious scientist disputes evolution when, in fact, there are quite a number who do so.


The disputant defends his belief on the grounds that you can’t prove him wrong.

The problem here is that either he has a reason for what he believes or he doesn’t. If he has no reason, then there’s nothing to disprove in the first place since his belief is admittedly irrational.

If he has a reason, then it’s either a good reason for a bad reason. If a good reason, he should be able to defend his belief through reason. If a bad reason, then his belief is unwarranted—especially when attention is draw to its deficiencies.

From a theological standpoint, the Christian faith is a revealed religion. Hence, the burden is upon the believer to justify his faith as a faith founded on divine revelation. He only has a right to believe revealed truth.


This may or may not be a fallacy. It varies from case to case. As a rule, the absence of evidence is not evidence for the absence of an event.

For example, unbelievers often deny Bible history unless it is corroborated at every point. But this imposes an unreasonable standard on what we can expect to have survived the passage of time—not to mention the fact that some events are essentially private. The unbeliever has had many experiences of a personal nature for which there were no eyewitnesses or other records.

On the other hand, there are circumstances in which we would expect something additional to be said if something additional had happened. For example, if Paul had died by the time Luke wrote the Book of Acts, it’s surprising that no mention is made of that event. If Isaiah was written during the Exile, it’s surprising that there is no incidental information on daily life in Mesopotamia—such as we find in a truly Exilic prophet like Ezekiel. If Galatians was written before the Council of Jerusalem (Acts 15), it is surprising that Paul didn’t play this trump card.


I am going to distinguish between an ad hominem argument and an ad hominem attack. In an ad hominem argument, the disputant argues from his opponent’s own assumptions and methods. You try to show that his operating premise is false, or his conclusion is invalid. Your assume your opponent’s burden of proof.

An ad hominem argument is a perfectly legitimate form of reasoning. It doesn’t prove the disputant’s position to be true, but it proves the opponent’s position to be false. And that is a necessary step in apologetics.


As distinguished from an ad hominem argument, an ad hominem attack is not about the merits of the case, but about the merits of the man.

An ad hominem attack is a special case of the genetic fallacy. The disputant attacks the character and credentials of his opponent to impeach his credibility. If he can’t find anything wrong with him, he will shift to guilt-by-association.

An ad hominem attack is often characterized by a heavy dose of invective and labeling. Indeed, it may be pure invective, as a substitute for reasoned argument.

As soon as the opponent is classified as a “fundamentalist,” “rightwing extremist,” “creationist,” there is nothing more to say—as if mere assignment to a certain social class were any sort of argument against one’s membership in said class.

There is nothing wrong with labeling. But at some point the disputant needs to make a case for why, exactly, such group-membership is invidious.

As a rule, this is a red herring. Even if the opponent were a hypocrite, his position may still be true. May well be true.

A very influential version of the ad hominem attack is the Freudian analysis of faith as wishful thinking. This has its sociological counterpart in the theories of Marx and Durkheim.

The assumption here is that if faith serves a certain function, it is reducible to a functional role, as if there’s no external referent which answers to the object of faith.

A problem with this line of argument is that it cuts both ways, for unbelief is also subject to a functional analysis. The unbeliever is suffering from a father-complex, negative transference, secular social conditioning, &c.

Having said all that, there are circumstances in which an ad hominem attack is legitimate. For example, it’s not prudent to hire a homosexual Scout master, or a philanderer to serve as your pastor, or a convicted embezzler to be a bank executive.

There are also situations in which it is not inappropriate to judge a man by the company he keeps. If a man spends his evenings and weekends at the local bathhouse, that is a pretty good indication of his sexual orientation.

At the same time, we need to distinguish between first-degree and second-degree association. If I have a brother who belongs to a street gang, that doesn’t make me a gang-banger.

The ad hominem attack can sometimes refute the argument from authority, for a man’s credentials, or lack thereof, may be relevant to his expertise, or lack thereof. At the same time, there are incompetent PhDs as well as competent autodidacts. So, generally, you have to judge a position by the quality of the supporting arguments, and not the resume of the disputant or his opponent.

An ad hominem attack is also legitimate when bad behavior is a logical consequence of a particular belief or belief-system.


The disputant appeals to his own assumptions and standards to disprove the opponent’s position, when his assumptions and standards are the very point at issue. This is the flip-side of the ad hominem argument.

For example, a materialist will “disprove” the existence of God by insisting that only empirical evidence counts for or against an existential proposition. Since God, if there is a God, is a supersensible being, he cannot be an object of sense knowledge, and cannot, therefore, be an object of knowledge at all.

But this begs the question by insisting on a particular epistemology which, in turn, prejudges what is knowable.

A quite common example of question-begging is where the disputant will make a groundless assertion instead of an argument. Rather than argue for his assertion, his bare, baseless assertion becomes a substitute for reason and evidence.


The disputant confuses the properties of one domain with another. For example, Augustine’s privative theory of evil sets up a correspondence between degrees of being and degrees of good, which conflates ethics and metaphysics.


The disputant gives a reason for why he doesn’t believe the opposing position. His opponent refutes his objection. The disputant cannot point to any flaw in his opponent’s refutation. But instead of withdrawing his original objection, the disputant simply changes the subject.


There are two kinds of circular reasoning: vicious and virtuous.

i) Vicious circularity is a special case of begging the question. Vicious circularity is where you reproduce the premise in the conclusion. Instead of showing that y follows from x because y is a subset of x, and if x is true, then y is true, you simply paraphrase your original claim, so that you’ve done nothing to advance the argument. You seem to give reason x for your belief in y, but x and y are really the same thing.

Vicious circularity is usually a bit more roundabout than this bare-bones outline. For example, this is how a Roman Catholic will often argue for his faith:

“How do you know that the Catholic Church is not an apostate church?”
“ Because the Church is indefectible.”
“How do you know that?”
“Because Christ has promised us that the gates of hell will not overcome the church.”
“Haven’t the Popes made mistakes?”
“Only when expressing a private opinion, and not when speaking ex cathedra.”
“How do you know when a Pope is speaking ex cathedra or not?”
“If he made a mistake, he was not speaking ex cathedra.”
“Is it not possible for your church to commit apostasy?”
“No, for the true church is indefectible.”
“How do you know that your church is the true church?”
“Because she has never fallen into heresy.”
“How do you know she’s never fallen into heresy?”
“Because Christ has promised us that the gates of hell will not overcome the church.”

If you think this is a parody of Catholic reasoning, just read some of my exchanges with Roman Catholics.

ii) Virtuous circularity can take two forms:
a) It can be a special case of the ad hominem argument, where, for the sake of argument, the disputant will reason from his opponent’s assumptions and standards.
b) When it takes for granted whatever truth-conditions are necessary to reason at all—truth-conditions common to disputant and opponent alike.

On a side issue, it is often said that Van Tilian apologetics is viciously circular. However, Van Tilian apologetics is circular in the sense of (ii), not (i).

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