Archive

Archive for September, 2009

Association Fallacy

September 24th, 2009 Comments off

Association Fallacy

classification : inductive – fallacy of distraction

Which asserts that qualities of one thing are inherently qualities of another, merely by an irrelevant association.

Foundations

The two types are sometimes referred to as guilt by association and honor by association. Association fallacies are a special case of red herring, and can be based on an appeal to emotion. It can be committed in either a positive or negative (derogatory) fashion. In both cases, it is equally fallacious.

Examples

Hitler was a vegetarian. Hitler was pure evil. Therefore, vegetarians have evil ideals.

Other Names

Ad hominem

Reductio ad Hitlerum

Red Herring

Categories: Logic

Poisoning The Well

September 24th, 2009 Comments off

Taxonomy – Where am I?

Poisoning The Well

classification : informal – red herring – genetic fallacy – as hominem

A logical fallacy that uses the association of negative emotions to distract a subject from actual evidence in an argument. The usual method is to point out the unpleasant nature of the person making the opposing argument.

Foundations

Adverse information about a target is pre-emptively presented to an audience, with the intention of discrediting or ridiculing everything that the target person is about to say. Poisoning the well is a special case of argumentum ad hominem

Examples

“Everything I say is correct, no matter what you say”

“Don’t listen to him, he’s a scoundrel.”

Other Names

Argumentum ad hominem
Appeal to ridicule
Black propaganda
Guilt by association
Prolepsis ( a form of rhetoric )
Scorched earth
Smear Tactics
Smear Campaign

Note: Poisoning the Well as a rhetorical technique is not, strictly speaking, a logical fallacy since it is not a type of argument. Rather, it is a logical boobytrap set by the poisoner to tempt the unwary audience into committing an ad hominem fallacy. An argument must stand or fall on its own, regardless of who makes it.

Categories: Logic

Occam’s Razor

September 24th, 2009 Comments off

Occam’s Razor (law of parsimony)

Occam’s Razor is the principle that one should not multiply the agents in a theory beyond what’s necessary ( “non sunt multiplicanda entia praeter necessitatem” )

What does that mean? If two competing theories explain a single phenomenon, and they both generally reach the same conclusion, and they are both equally persuasive and convincing, and they both explain the problem or situation satisfactorily, the logician should always pick the less complex one. The one with the fewer number of moving parts, so to speak, is most likely to be correct. The idea is always to cut out extra unnecessary bits, hence the name “razor.”

Don’t speculate about extra hypothetical components if you can find an explanation that is equally plausible without them. All things being equal, the simpler theory is more likely to be correct, rather than one that relies upon many hypothetical additions to the evidence already collected.

Categories: Logic

One Single Proof

September 24th, 2009 Comments off

One Single Proof

classification : informal – rhetorical technique

Is a deceptive rhetorical flourish used primarily by denialists designed to apparently negate a preponderance of circumstantial evidence by claiming that without a specific key proof, the whole argument is invalid.

Foundations

The effectiveness of the technique is dependent on a sort of distortion of Occam’s razor whereby any evidence that does not provide the whole answer is ignored.

The fallacy often rests on the idea that without a particular key bit of information, the entire system will fall apart. While this is sometimes the case, particularly when dealing with mathematical proofs, forensic arguments often make use of large quantities of circumstantial evidence in such a way as to point directly to a cause without a single smoking gun

Example

Among deniers of the harmful effects of tobacco smoking (active and passive), demanding that public health authorities produce the death certificate of one person who died as a consequence of exposure to secondhand smoke, and, in the absence of such a death certificate, concluding that such exposure is innocuous.

Other Names

Smoking gun
Extraordinary claims require extraordinary evidence

Note: Rhetorical techniques such as Poisoning the Well is not, strictly speaking, a logical fallacy since it is not a type of argument. Rather, it is a logical boobytrap set by the poisoner to tempt the unwary audience into committing an ad hominem fallacy. An argument must stand or fall on its own, regardless of who makes it.

Categories: Logic

Red Herring

September 24th, 2009 Comments off
Categories: Logic

Straw-Man

September 24th, 2009 Comments off

Taxonomy – Where am I?

Straw-Man

classification : informal – red herring

An intentional misrepresentation of an opponent’s position, often used in debates with unsophisticated audiences to make it appear that the opponent’s arguments are more easily defeated than they are.

Foundations

A fallacy in which an irrelevant topic is presented in order to divert attention from the original issue. The basic idea is to “win” an argument by leading attention away from the argument and to another topic.

Presenting and refuting a weakened form of an opponent’s arguments can be a part of a valid argument. For example, one can argue that the opposing position implies that at least one other statement—being presumably easier to refute than the original position—must be true. If one refutes this weaker proposition, the refutation is valid and does not fit the above definition of a “straw man” argument.

Categories: Logic

No True Scotsman

September 24th, 2009 Comments off

Taxonomy – Where am I?

No True Scotsman

classification : informal – fallacies of ambiguity

A logical fallacy by which an individual attempts to avoid being associated with an unpleasant act by asserting that no true member of the group they belong to would do such a thing.

Foundations

The term was coined by Antony Flew, who gave an example of a Scotsman who sees a newspaper article about a series of sex crimes taking place in Brighton, and responds that no Scotsman would do such a thing. When later confronted with evidence of another Scotsman doing even worse acts, his response is that no true Scotsman would do such a thing, thus disavowing membership in the group “Scotsman” to the criminal on the basis that the commission of the crime is evidence for not being a Scotsman. However, this is a fallacy as there is nothing in the definition of “Scotsman” which makes such acts impossible.

Categories: Logic

Negative Proof

September 24th, 2009 Comments off

Taxonomy – Where am I?

Negative Proof (argumentum ad ignorantiam)

classification : informal

If the only evidence for something’s existence is a lack of evidence for it not existing, then the default position is one of skepticism and not credulity.

Foundations

It is claimed that a premise is true only because it has not been proven false, or is false only because it has not been proven true.Note: Negative Proof is a special case of the fallacy of Denying The Antecedent if we accept the additional premise that observing a phenomenon implies that it exists. (Denying The Antecedent is a formal fallacy of propositional logic.)

Other Names

argument from ignorance
argumentum ad ignorantiam

Note: Irving Copi writes that:

The argumentum ad ignorantiam [fallacy] is committed whenever it is argued that a proposition is true simply on the basis that it has not been proven false, or that it is false because it has not been proven true.[…] A qualification should be made at this point. In some circumstances it can be safely assumed that if a certain event had occurred, evidence of it could be discovered by qualified investigators. In such circumstances it is perfectly reasonable to take the absence of proof of its occurrence despite searching, as positive evidence towards its non-occurrence. (Copi 1953)

Categories: Logic

Appeal To Force (Argumentum ad Baculum)

September 24th, 2009 Comments off

Taxonomy – Where am I?

Appeal To Force  ( Argumentum ad Baculum )

classification : informal – red herring – appeal to consequences

Argumentum ad Baculum (fear of force): the fallacy committed when one appeals to force or the threat of force to bring about the acceptance of a conclusion.

Foundations

The ad baculum derives its strength from an appeal to human timidity or fear and is a fallacy when the appeal is not logically related to the claim being made. In other words, the emotion resulting from a threat rather than a pertinent reason is used to cause agreement with the purported conclusion of the argument.

Categories: Logic

Moving The Goalposts

September 24th, 2009 Comments off

Moving The Goalposts

classification : informal

A fallacy in which previously agreed upon standards for deciding an argument are arbitrarily changed once they have been met.

Foundations

This is usually done by the “losing” side of an argument in a desperate bid to save face. If the goalposts are moved far enough, then the standards can eventually evolve into something that cannot be met no matter what. Usually such a tactic is spotted quickly.

Categories: Logic