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Archive for September, 2009

Tu quoque Argument

September 25th, 2009 Comments off

Taxonomy – Where am I?

Tu quoque Argument

classification : informal – red herring – two wrongs make a right

attempts to discredit the opponent’s position by asserting his failure to act consistently in accordance with that position; it attempts to show that a criticism or objection applies equally to the person making it.

Foundations

It is considered an ad hominem argument, since it focuses on the party itself, rather than its positions. In many cases tu quoque arguments are used in a logically fallacious way, to draw a conclusion which is not supported by the premises of the argument.

Examples

He cannot accuse me of libel because he was just successfully sued for libel.

You say aircraft are able to fly because of the laws of physics, but this is false because twenty years ago you also said aircraft fly because of magic.

Other Names

Argumentum ad Hominem

Two Wrongs Make a Right

Pot calling the kettle black

Categories: Logic

Galileo Gambit

September 25th, 2009 Comments off

Galileo Gambit

classification : informal – Straw man

The Galileo fallacy is the idea that if you are widely vilified for your ideas, you must therefore be right.

Foundations

“The fact that some geniuses were laughed at does not imply that all who are laughed at are geniuses. They laughed at Columbus, they laughed at Fulton, they laughed at the Wright brothers. But they also laughed at Bozo the Clown.” –Carl Sagan

Examples

They made fun of Galileo, and he was right. They make fun of me, therefore I am right.

Almost everyone thought Galileo was wrong, but he turned out to be right. Therefore, just because almost everyone thinks something is true, doesn’t make it so.

Don’t lecture me about my report card. Eisenstein was a poor student and look how he turned out.

Other Names

argumentum ad populum

argument from consensus

Categories: Logic

Pascal’s Wager

September 25th, 2009 Comments off

Pascal’s Wager

classification : informal – fallacy of distraction

An argument based on probability theory for why one should live as if God exists, even though this cannot be proved or disproved through reason formulated by Blaise Pascal.

Foundations

Mathematically a finite gain or loss is negligible compared to an infinite gain or loss. Therefore, he concluded that it was a much better choice to believe in God rather than to practice atheism.

Illustration

1. If you believe in God and God does exist, you will be rewarded with eternal life in heaven; thus an infinite gain.
2. If you do not believe in God and God does exist, you will be condemned to remain in hell forever; thus an infinite loss.
3. If you believe in God and God does not exist, you will not be rewarded; thus a finite loss.
4. If you do not believe in God and God does not exist, you will not be rewarded, but you have lived your own life; thus a finite gain.

Other Names

False Dilemma

Categories: Logic

Pattern Recognition

September 25th, 2009 Comments off

Pattern Recognition

classification : informal – fallacy of distraction

A computational algorithm used to classify raw data (sometimes appropriate action choice is included in the definition).

Foundations

The term is from machine learning, but has been adapted by cognitive psychologists to describe various theories for how the brain goes from incoming sensory information to action selection.

Illustration

The various stages of pattern recognition include:

  • Sensor to detect source data (such as the retina for photon reflection)
  • Feature detection in the incoming data (such as border detection, orientation and color)
  • Classification of data based on features (seeing a “tree” or a “keyboard”)
  • Action selection based on classification (jumping out of the way of a moving car coming towards you, not worrying about a moving fly coming towards you)

The pervasiveness of false pattern recognition in human cognition means that it often plays a role in our attempts at reasoning. A large number of informal logical fallacies have been constructed to highlight how this comes out in arguments.

Other Names

Texas Sharpshooter Fallacy

Confirmation bias

Correlation does not equal causation

Categories: Logic

Texas Sharpshooter Fallacy

September 25th, 2009 Comments off

Taxonomy – Where am I?

Texas Sharpshooter Fallacy

classification : informal – non causa pro causa

Using the same data to both construct and test a hypothesis. A data mining fallacy and pattern recognition error where the arguer makes an ad hoc conclusion from a set of unrelated data without looking for corroborating data.

Foundations

Its name comes from a parable where a Texan fires his gun at the side of a barn, then paints a target around the shots and claims to be a sharpshooter. A hypothesis must be constructed before data is collected based on that hypothesis. If one data set is used to construct a hypothesis, then a new data set must be generated (ideally, in a different way, based on predictions made by the hypothesis) to test it.

Examples

This fallacy is often found in modern-day interpretations of the quatrains of Nostradamus. Nostradamus’s quatrains are often liberally translated from the original (archaic) French, stripped of their historical context, and then applied to support the conclusion that Nostradamus predicted a given modern-day event, after the event actually occurred.

Other Names

Confirmation bias
Cum hoc ergo propter hoc
Post hoc ergo propter hoc
Correlative based fallacies
Moving the goalpost, a related fallacy used to obtain the opposite conclusion.

Categories: Logic

Spotlight Fallacy

September 25th, 2009 Comments off

Spotlight Fallacy

classification : informal – fallacy of distraction

The spotlight fallacy occurs when observed data is incorrectly assumed to represent a different or larger group.

Foundations

Receiving a great deal of attention or coverage is often referred to as being in the spotlight. It is similar to Hasty Generalization, Biased Sample and misleading because the error being made involves generalizing about a population based on an inadequate or flawed sample.

Examples

“Kids these days are so much more violent; I see all these stories about school violence.”

Other Names

Biased Sample

Hasty Generalization

Categories: Logic

Argumentum ad verecundiam

September 25th, 2009 Comments off

Argumentum ad verecundiam

classification : informal – defective induction

Appeal to inappropriate authority. When correctly applied this can be a valid appeal to authority, essentially it is an argument that requests judgment or input from a qualified or expert source. Frequently, however, it is often a logical fallacy consisting of an appeal to authority, but on a topic outside of the authority’s expertise or on a topic on which the authority is not disinterested (i.e., is biased). Almost any subject has an authority on every side of the argument, even where there is generally agreed to be no argument.

Included Fallacies

False Cause (argument non causa pro cause)
Appeal to Authority
Hasty Generalization (converse accident)
Appeal to the Public
Misuse of Authority
Irrelevant Authority
Inappropriate Authority
Questionable Authority

Categories: Logic

Bandwagon Fallacy

September 25th, 2009 Comments off

Bandwagon Fallacy

classification : informal – fallacy of relevance

One argues for an idea based upon an irrelevant appeal to its popularity.

Foundations

The logical argument here is:

Everyone (the majority) is doing it.
The majority is always right.
If I do it, I will be in the majority, therefore right.

Unfortunately, the premise “the majority is right” may not be true.

Examples

Since 88% of the people polled believed in UFOs, they must exist.

In a court of law, the jury vote by majority, therefore they will always make the correct decision.

Other Names

Appeal to Popularity

Argument by Consensus

Argumentum ad Populum

Authority of the Many

Categories: Logic

Argumentum ad populum

September 25th, 2009 Comments off

Argumentum ad populum

classification : informal – informal fallacy of defective induction

(literally, an argument to the people) is the logical fallacy that just because something is popular, it is therefore true. Undoubtedly many popular notions are true, but their truth is not a function of their popularity.

This logical fallacy is often used by children as an excuse for wanting something (everybody’s got one), or doing something (everybody’s doing it). Despite the juvenile nature of the argument, it is often used by people who should know better, particularly by those who are trying to force other people to their way of thinking.

Included Fallacies

Appeal to the masses
Appeal to belief
Appeal to the majority
Appeal to the people
Argument by consensus
Authority of the many
Bandwagon fallacy

Categories: Logic

My Enemy’s Enemy

September 24th, 2009 Comments off

My Enemy’s Enemy

classification : non-sequiters

My enemy’s enemy is my friend is an old Arab saying. It explains some strange political, religious and epistemological alliances.

Foundations

Using a common enemy as the basis for an allegiance is problematic because there are probably very few other areas for common ground, and absent the common enemy, the friends might otherwise be enemies themselves. If the common enemy disappears, the allies might turn on each other.

Examples

Pilot fish clean parasites off larger predators like sharks. These smaller fish swim freely around the sharks and even inside the mouths of the sharks that could easily eat the small fish. Since the shark’s enemy is the parasite and the parasite’s enemy is the smaller fish, the shark considers the Pilot fish a “friend” and accommodates an otherwise potential food source.

Other Names

The enemy of my enemy is my friend is one of four rules in the rule of triadic interaction. The others are: “the friend of my friend is my friend”, “the friend of my enemy is my enemy” and “the enemy of my friend is my enemy”.

Note1: “non-sequiters”, Latin for “it does not follow” are fallacies that are based purely on rules of logic, prior to examining any evidence, in which the conclusion logically does not follow from the premise.

Note2: Using a common enemy as the basis for an allegiance is problematic because there are probably very few other areas for common ground, and absent the common enemy, the friends might otherwise be enemies themselves. If the common enemy disappears, the allies might turn on each other.

Categories: Logic