logical fallacies

Question 1

What is required for an arguement to be valid

Answer 1

A valid argument is one in which, if the premises are true, then the conclusion must be true also

However, if one or more premise is false then a valid logical argument may still lead to a false conclusion.

Question 2

What is a SOUND argument

Can unsound arguments lead to a true conclusion?

For what reason should you be careful about conclusions?

Answer 2

A sound argument is one in which the logic is valid and the premises are true, in which case the conclusion must be true.

Yes, unsound arguments can lead to a true conclusion –> therefore be careful because you may know an argument is unsound or invalid does not mean the conclusion is false, it just means its not necessarily true

Question 3

Can you name the three big potential problems with premises

Answer 3

1) They may be untrue; or true but not complete, i.e. the premises are not wrong, but do not cover the relevant facts necessary to argue the conclusion.
2) Premises may be based on unwarranted assumptions (Identifying all the assumptions upon which an argument is dependent is often the most critical step in analyzing an argument. )
3) The hidden premise. (The most insidious). E.g. when one side of an argument uses a different definition for a term (perhaps an unusual definition)

Question 4

What is rationalisation

Answer 4

When an argument is constructed to fit a conclusion (what most people do) that’s already been decided upon

Question 5

What are logical short-cuts known as

Answer 5

heuristics

These are thought processes that are not strictly valid in their logic, but are true most of the time and therefore are a useful rule-of-thumb as to what is likely to be true. But they get us into trouble when they substitute for valid logic.

Question 6

What is an ad hominem logical fallacy

Answer 6

An ad hominem argument is any that attempts to counter another’s claims or conclusions by attacking the person, rather than addressing the argument itself.

E.g. dismissing somebodies conclusions because you think they are stupid

A common form of this fallacy is also frequently present in the arguments of conspiracy theorists (who also rely heavily on ad-hoc reasoning). For example, they may argue that the government must be lying because they are corrupt.

Question 7

What is Godwin’s law?

How is it otherwise known in comedy latin

Answer 7

It is a type of ‘poisoning the well’ which is itself a type of ad hominem falacy

It is also known as reductio ad Hitlerum

Essentially, it refers to an attempt at poisoning the well by drawing an analogy between another’s position and Hitler or the Nazis.

Question 8

What is the Ad ignorantiam logical fallacy

Answer 8

The argument from ignorance basically states that a specific belief is true because we don’t know that it isn’t true.

E.g. emphasising how much we don’t know about the brain or universe to support some wacky claim

UFO proponents are probably the most frequent violators of this fallacy. Almost all UFO eyewitness evidence is ultimately an argument from ignorance – lights or objects sighted in the sky are unknown, and therefore they are alien spacecraft.

Intelligent design is almost entirely based upon this fallacy.

Question 9

What is an argument from authority

What is its converse

What are two most well known sub-types

Answer 9

The basic structure of such arguments is as follows: Professor X believes A, Professor X speaks from authority, therefore A is true. Often this argument is implied by emphasizing the many years of experience, or the formal degrees held by the individual making a specific claim.

The converse of this argument is sometimes used, that someone does not possess authority, and therefore their claims must be false. (This may also be considered an ad-hominen logical fallacy)

This can be tricky because authority such as scientific concensus does have weight

Two most popular subtypes are

Argument ad populum (lots of people believe it therefore…)

Argument from antiquity (because its old or been around a long time….)

Question 10

What is the argument of final consequences fallacy

Answer 10

They are reverse of cause and effect thinking, e.g. argument that something is caused by the ultimate effect it has / or purpose it serves

E.g. the universe has the properties to support life, therefore it was designed to support life

Question 11

What is the argument from personal incredulity

Answer 11

I cannot explain or understand something therefore it cannot be true

Question 12

What is Begging the Question

What is the classic example

Answer 12

It is a falacy whereby a conclusion is assumed in the question

The classic example:: Have you stopped beating your wife yet?

Question 13

What fallacy would be occuring in the following example

‘During the 1990s both religious attendance and illegal drug use were on the rise, therefore religious attendance causes illegal drug use

What is the converse of this fallacy

Answer 13

Confusing association with causation

It could be - illegal drug use leads to church attendance (repetence etc)

or they could both be associated with a third variable (social decline)

or it could be coincidence

The converse is the fallacy of denying causation

• e.g. denying data collected in controlled study (whereby other causes are controlled or ruled out)
• or if multiple independent correlations point to the same causal relationship (e.g. smoking and cancer)

Consider the following example:

The tobacco industry, invoking the “correlation is not causation” logical fallacy, argued that this did not prove causation. They offered as an alternate explanation “factor x”, a third variable that causes both smoking and lung cancer. But we can make predictions based upon the smoking causes cancer hypothesis. If this is the correct causal relationship, then duration of smoking should correlate with cancer risk, quitting smoking should decrease cancer risk, smoking unfiltered cigarettes should have a higher cancer risk than filtered cigarettes, etc. If all of these correlations turn out to be true, which they are, then we can triangulate to the smoking causes cancer hypothesis as the most likely possible causal relationship and it is not a logical fallacy to conclude from this evidence that smoking probably causes lung cancer.

Question 14

What are false analogies

What is the famous evolution example

Answer 14

A false analogy is an argument based upon an assumed similarity between two things, people, or situations when in fact the two things being compared are not similar in the manner invoked.

Saying that the probability of a complex organism evolving by chance is the same as a tornado ripping through a junkyard and created a 747 by chance is a false analogy. Evolution, in fact, does not work by chance but is the non-random accumulation of favorable changes.

Question 15

What is the fallacy of the false continuum

What is the similar but more converse version

Answer 15

The idea that because there is no definitive demarcation line between two extremes, that the distinction between the extremes is not real or meaningful: There is a fuzzy line between cults and religion, therefore they are really the same thing.

The similar converse is the false dichotomy - which is of course where the continuum is denying altogether leaving just ‘black or white’

Question 16

What is the ‘No true Scotsman’ fallacy

Answer 16

This fallacy is a form of circular reasoning, in that it attempts to include a conclusion about something in the very definition of the word itself. It is therefore also a semantic argument.

The term comes from the example: If Ian claims that all Scotsman are brave, and you provide a counter example of a Scotsman who is clearly a coward, Ian might respond, “Well, then, he’s no true Scotsman.”

In essence Ian claims that all Scotsman are brave by including bravery in the definition of what it is to be a Scotsman.

Question 17

What is the reductio ad absurdum fallacy

Answer 17

In formal logic, the reductio ad absurdum is a legitimate argument. It follows the form that if the premises are assumed to be true it necessarily leads to an absurd (false) conclusion and therefore one or more premises must be false.

The term is now often used to refer to the abuse of this style of argument, by stretching the logic in order to force an absurd conclusion. For example a UFO enthusiast once argued that if I am skeptical about the existence of alien visitors, I must also be skeptical of the existence of the Great Wall of China, since I have not personally seen either.

Question 18

What is the slippery slope fallacy

Answer 18

This logical fallacy is the argument that a position is not consistent or tenable because accepting the position means that the extreme of the position must also be accepted.

But moderate positions do not necessarily lead down the slippery slope to the extreme.

Question 19

What is the other name for special pleading?

What is it

Answer 19

Ad hoc reasoning

In essence, it is the arbitrary introduction of new elements into an argument in order to fix them so that they appear valid

A good example of this is the ad-hoc dismissal of negative test results.

Question 20

What is a tautology

Answer 20

Tautology in formal logic refers to a statement that must be true in every interpretation by its very construction.

In rhetorical logic, it is an argument that utilizes circular reasoning, which means that the conclusion is also its own premise.

The structure of such arguments is A=B therefore A=B, although the premise and conclusion might be formulated differently so it is not immediately apparent as such.

For example, saying that therapeutic touch works because it manipulates the life force is a tautology because the definition of therapeutic touch is the alleged manipulation (without touching) of the life force.

Question 21

What is the fallacy fallacy

Answer 21

just because someone invokes an unsound argument for a conclusion, that does not necessarily mean the conclusion is false.

Question 22

What is the moving goalpost logical fallacy

Answer 22

A method of denial that involves arbitrarily moving the criteria for “proof” or acceptance out of range of whatever evidence currently exists.

If new evidence comes to light meeting the prior criteria, the goalpost is pushed back further – keeping it out of range of the new evidence. Sometimes impossible criteria are set up at the start – moving the goalpost impossibly out of range – for the purpose of denying an undesirable conclusion.

Question 23

What is the Tu quoque logical fallacy

Answer 23

Literally, you too. This is an attempt to justify wrong action because someone else also does it. “My evidence may be invalid, but so is yours.”

Question 24

What is the gambler’s fallacy

Answer 24

This commonly believed fallacy can be said to have helped create an entire city in the desert of Nevada USA. Though the overall odds of a ‘big run’ happening may be low, each spin of the wheel is itself entirely independent from the last. So whilst there may be a very small chance that heads will come up 20 times in a row if you flip a coin, the chances of heads coming up on each individual flip remain 50/50, and aren’t influenced by what happened before.

Example: Red had come up six times in a row on the roulette wheel, so Greg knew that it was close to certain that black would be next up.

Question 25

What is the composition / division fallacy

Answer 25

You assumed that one part of something has to be applied to all, or other, parts of it; or that the whole must apply to its parts.

Example: Daniel was a precocious child and had a liking for logic. He reasoned that atoms are invisible, and that he was made of atoms and therefore invisible too.

Question 26

What is the texas sharpshooter fallacy

Answer 26

This ‘false cause’ fallacy is coined after a marksman shooting randomly at barns and then painting bullseye targets around the spot where the most bullet holes appear, making it appear as if he’s a really good shot. Clusters naturally appear by chance, but don’t necessarily indicate that there is a causal relationship.

Question 27

What is the middle ground fallacy

Answer 27

Much of the time the truth does indeed lie between two extreme points, but this can bias our thinking: sometimes a thing is simply untrue and a compromise of it is also untrue. Half way between truth and a lie, is still a lie.

Example: Holly said that vaccinations caused autism in children, but her scientifically well-read friend Caleb said that this claim had been debunked and proven false. Their friend Alice offered a compromise that vaccinations must cause some autism, just not all autism.

Question 28

What is a loaded question?

Answer 28

You asked a question that had a presumption built into it so that it couldn’t be answered without appearing guilty.

Example: Grace and Helen were both romantically interested in Brad. One day, with Brad sitting within earshot, Grace asked in an inquisitive tone whether Helen was having any problems with a drug habit.

Question 29

What is the burden of proof problem

Answer 29

The burden of proof lies with someone who is making a claim, and is not upon anyone else to disprove.

Bertrand declares that a teapot is, at this very moment, in orbit around the Sun between the Earth and Mars, and that because no one can prove him wrong, his claim is therefore a valid one. (this is also an argument from ignorance)

Question 30

What is a base rate fallacy

(careful this is quite sophisticated)

Answer 30

Also called base rate neglect or base rate bias, is an error in thinking. If presented with related base rate information (i.e. generic, general information) and specific information (information only pertaining to a certain case), the mind tends to ignore the former and focus on the latter.

Example

John is a man who wears gothic inspired clothing, has long black hair, and listens to death metal. How likely is it that he is a Christian and how likely is it that he is a Satanist?

If people were asked this question, they would likely underestimate the probability of him being a Christian, and overestimate the probability of him being a Satanist. This is because they would ignore that the base rate of being a Christian (there are about 2 billion in the world) is vastly higher than that of being a Satanist (estimated to be in the thousands)

Question 31

What is a conjunction fallacy

Answer 31

The conjunction fallacy is a formal fallacy that occurs when it is assumed that specific conditions are more probable than a single general one.

Linda is 31 years old, single, outspoken, and very bright. She majored in philosophy. As a student, she was deeply concerned with issues of discrimination and social justice, and also participated in anti-nuclear demonstrations.

Which is more probable?

Linda is a bank teller.

Linda is a bank teller and is active in the feminist movement.

the answer is one (think about it). The reason people think 2 is because of the heuristic of representativeness, i.e. the second option seems to better ‘represent’ Linda

Question 32

What is the masked man fallacy (and by what other name is it known)

Answer 32

In philosophical logic, the masked man fallacy (also known as the intensional fallacy and the epistemic fallacy is committed when one makes an illicit use of Leibniz’s law in an argument.

Leibniz’s law states that, if one object has a certain property, while another object does not have the same property, the two objects cannot be identical. The name of the fallacy comes from the example:

Premise 1: I know who Jones is.

Premise 2: I do not know who the masked man is

C

onclusion: Therefore, Jones is not the masked man.

The thing is, there is a difference between ‘being something’ and ‘believing something’

The premises may be true and the conclusion false if Jones is the masked man and the speaker does not know that. Thus the argument is a fallacious one.

Question 33

What is the reduction fallacy

Answer 33

The fallacy of the single cause, also known as complex cause, causal oversimplification, causal reductionism, and reduction fallacy, is a fallacy of questionable cause that occurs when it is assumed that there is a single, simple cause of an outcome when in reality it may have been caused by a number of only jointly sufficient causes.

For instance, after a school shooting, editorialists debate whether it was caused by the shooter’s parents, violence in media, stress on students, or the accessibility of guns. In fact, many different causes—including some of those—may all have necessarily contributed. Similarly, the music industry might claim that peer-to-peer file sharing is the cause of a loss in profit whereas factors such as a growing videogame market and economic depression are also likely to be major factors.

Question 34

What is the Affirming the Consequent aka converse error

Answer 34

If P, then Q

Q

Therefore P

Because the conclusion can be false even if premises one and two are correct

e.g.

If Bill Gates owns Fort Knox, then he is rich.

Bill Gates is rich.

Therefore, Bill Gates owns Fort Knox.