logical fallacies Flashcards
(34 cards)
What is required for an arguement to be valid
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.
What is a SOUND argument
Can unsound arguments lead to a true conclusion?
For what reason should you be careful about conclusions?
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
Can you name the three big potential problems with premises
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)
What is rationalisation
When an argument is constructed to fit a conclusion (what most people do) that’s already been decided upon
What are logical short-cuts known as
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.
What is an ad hominem logical fallacy
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.
What is Godwin’s law?
How is it otherwise known in comedy latin
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.
What is the Ad ignorantiam logical fallacy
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.
What is an argument from authority
What is its converse
What are two most well known sub-types
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….)
What is the argument of final consequences fallacy
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
What is the argument from personal incredulity
I cannot explain or understand something therefore it cannot be true
What is Begging the Question
What is the classic example
It is a falacy whereby a conclusion is assumed in the question
The classic example:: Have you stopped beating your wife yet?
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
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.
What are false analogies
What is the famous evolution example
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.
What is the fallacy of the false continuum
What is the similar but more converse version
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’
What is the ‘No true Scotsman’ fallacy
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.
What is the reductio ad absurdum fallacy
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.
What is the slippery slope fallacy
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.
What is the other name for special pleading?
What is it
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.
What is a tautology
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.
What is the fallacy fallacy
just because someone invokes an unsound argument for a conclusion, that does not necessarily mean the conclusion is false.
What is the moving goalpost logical fallacy
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.
What is the Tu quoque logical fallacy
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.”
What is the gambler’s fallacy
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.
