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Implications and Debate: an excellent article on charity, giving a much fuller treatment that the following from May, 2005 on my blog)

We seem to have lost the concept of charity in debate. I'm talking about debate as it's waged on blogs and talk shows.

In a debate, the principle of charity dictates that you interpet opposing arguments in the most favorable light. Rather than pick apart an opposing point the way it was made, you (perhaps silently) make the point the way it should have been made and then analyze the result. If you construct a stronger opposing case and defeat it, you can be more confident in the correctness of your position.

If your goal is to search for truth, then charity is a strong ally.

However, if your goal is simply to "win" the argument, then you can ignore charity. You should know that in many instances your victory will be hollow. There are times when a hollow victory is most expedient. But it may be that you defeat only the presentation of an opposing viewpoint, when you could achieve much more.

For if you approach a debate with charity, those in the audience will see in you a greater understanding. Your opponents will be more inclined to offer you charity. Your focus will be on the flaws in the opposing position, rather than on the opposing debater. That will enable you to point out any flaws that exist.

And finally, charity enables you to accept any valid points that your opponent makes, regardless of the quality of their presentation. Someday you may even "lose" a debate when you realize that your opponent missed a convincing point. There is no shame in changing your mind when you discover the truth about a matter.

Cum hoc ergo propter hoc

Latin for "With this, therefore because of this".

Two events that occur together in time, space, or otherwise, need not be causally related, and in particular, colocation does not imply which one is cause and which one effect. Even if normally one type of event causes another, it is only an assumption to assert cause and effect.

For instance, if a man shoots a gun in a crowded room, and someone falls down, it doesn't mean that the gunshot hit the person, causing the fall. There could have been another gun, or the fall could have been in reaction to the noise, or the person could have tripped over the dog.

See also post hoc ergo propter hoc.

Both are special cases of non causa pro causa.


By putting stress on a particular word, the meaning of an argument can be obscured.

Post hoc ergo propter hoc

Latin for "After this, therefore because of this".

An event that follows another need not be caused by it, even if generally events of the first type cause events of the second.

See also cum hoc ergo propter hoc.

Both are special cases of non causa pro causa.


Wizard Google

The fallacies of Ambiguity include those which use language in imprecise ways to obscure or misdirect the argument.
Philosophy Pages says these include

Bruce Thompson:
Fallacies of Ambiguity involve some confusion over meaning. Interpreted in one way the argument has a false major premiss, while interpreted in the other way the argument has a false minor premiss. (If we try to interpret both premisses so that they are true, then the "argument" fails to be formally valid.) Here is an obvious example:
All beetles have six legs.
John Lennon is a Beatle.
Hence, John Lennon has six legs.

Since the location of the fallacy is a matter of interpretation, we cannot classify the argument either as a major-premiss fallacy or as a minor-premiss fallacy. Hence such fallacies get their own group.

Fallacy Files:
A categorical syllogism is, by definition, an argument with three categorical terms. "Term" is to be understood in a semantic sense, as opposed to the syntactic sense of "word" or "phrase". In other words, it is the meaning of the words that is important. So, two different words with the same meaning are the same term, and the same word occurring twice with different meanings is two distinct terms. An argument commits the Four Term Fallacy which appears to have the form of a validating categorical syllogism, but has four terms.


The fallacy of accident / Sweeping generalization / Dicto simpliciter


Bruce Thompson:

The argument draws a conclusion from an over-simplistic statement of a rule. This takes two forms:

Destroying the Exception by insisting on the rule, which is called Accident, and

Destroying the Rule by insisting on the exception, which is called Reverse Accident (or in Latin, Secundum Quid).

In either case, the exception falls outside the scope of the rule--or would, if the rule were stated more accurately.

Fallacy Files:


Birds normally can fly.
Tweety the Penguin is a bird.
Therefore, Tweety can fly.


The fallacy of Accident, one of Aristotle's thirteen fallacies, has been interpreted in various ways by subsequent logicians, perhaps because of the obscurity of The Philosopher's account. I will discuss only one of these interpretations here, due to its relation to recent developments in logic.

Consider the generalization "birds can fly" from the example. Now, it isn't true that all birds can fly, since there are flightless birds. "Some birds can fly" and "many birds can fly" are too weak. "Most birds can fly" is closer to what we mean, but in this case "birds can fly" is a "rule of thumb", and the fallacy of Accident is a fallacy involving reasoning with rules of thumb.

Logic Wizard

This blog is an attempt to apply Google's 'search don't sort' concept to the documentation of a field of study. Rather than create documents interlinked in a wiki-style mess, the idea is to have many, many small documents, each of which describes some particular aspect of the field.

Specifically, this blog is an attempt to do what others have done, create a site documenting informal logic and fallacies, useful both for the expert and the novice.

Some entries will consist mainly of a web search on a given concept, with commentary on excerpts from various sites explaining that topic, and links to them. Others may be a simple definition of a term. There is a lot of overlap in the terminology. For instance, many fallacies have an English name, a Latin name, and several subtypes. Using the combination of full-text search and tags, the relationships between concepts may be clearer than a wiki-style reference could be.

Each of the informal logic sites I've found has an index of some kind, and its own categorization for the various fallacies. Rather than make my own categorization, I will tag each fallacy or concept with the attributes that apply to it.

Denying the Antecedent

An argument of the form
A → B.
Not A.
∴ not B

A implies B. Not A. Therefore, not B.

In a three-part hypothetical syllogism, the proper form is
A → B.
Not B.
∴ not A

In other words, since A means B, we would see B if there had been A. But we don't see B, so there cannot have been any A.

Fallacially, this would be that since A means B, there must have been A to have B. But we don't see A, so there cannot have been any B. The error is in assuming that just because we get B when when we have A, that the only way to get B is with A.

This is the converse of the fallacy of Affirming the Consequent.

Affirming the Consequent

An argument of the form
A → B.
∴ A.

A implies B. B. Therefore, A.

In a three-part hypothetical syllogism, the proper form is
A → B.
∴ B.

In other words, since A means B, and we have A, there must be B.

Fallacially, this would be that since A means B, seeing B we must have A. The error is in assuming that just because we get B when when we have A, that the only way to get B is with A.

This is the converse of the fallacy of Denying the Antecedent.

Argument to Tradition

Argumentum ad antiquitatem (the argument to antiquity or tradition). Humans generally accept their environment. The "way it's done" may or may not be the best way, even if it were the best way when it became the common practice.

Appeals to tradition are an attempt to set the burden of proof. They can thus be proper or improper, but when the goal of the argument is to show that a practice is reasonable or good, its current state of popularity may be irrelevant.