Speech 140- Logos and Logical Fallacies

One of Aristotle's three main arguments- the argument itself or logic

Inductive vs. Deductive

1. Inductive- the premises provide reasons supporting the probable and likely truth of the conclusion

2. Deductive- the premises provide a guarantee of the truth of the conclusion

A three-part argument Consisting of two premises, the truth of which guarantees the truth of the conclusion

An argument in which the premises do not provide enough support for the conclusion- an error in the reasoning process

Provides support for a conclusion but not a guarantee that it is true

1. Fallacies of Relevance
2. Component Fallacies
3. Fallacies of Ambiguity
4. Fallacies of Omission

Appeals to evidence or examples that are not relevant to the argument at hand

Consists of:
1. Argument ad hominem
2. Argument ad populem
3. Appeal to Tradition
4. Appeal to Improper Authority
5. Red Herring Argument

Errors in reasoning or in syllogistic terms that fail to connect

Consists of:
1. Begging the question
2. Hasty generalization
3. Fallacy of accident
4. Misleading statistics
5. Common cause fallacy
6. Post hoc fallacy
7. Slippery slope fallacy
8. False Dilemma Fallacy

Occur because of the use of ambiguous words or phrases, whose meanings shift throughout the course of the argument

Consists of:
1. Fallacy of equivocation
2. Fallacy of Composition
3. Fallacy of Division

Occur because necessary material is left out of the argument, misdirecting the audience from the missing information

Consists of:
1. Appeal to ignorance or lack of evidence
2. Stacking the deck
3. Complex question

AKA "appeal to lack of evidence"

Claims that because that because something has never been proven false, it is true and vise versa

No evidence confirms or denies the argument's conclusion

An argument that ignores examples that disprove one's point and lists only those examples that support it

Phrasing a statement/question that implies another unproven statement is true without evidence

Often makes the answerer seem or say something negative

Attacking or praising the person making the argument rather than the argument itself

An argument that says a proposition is true because may people believe it to be son

An argument that assumes that a value, belief, policy or course of action should continue because it is part of a tradition

Provides no evidence for why the tradition should be maintained and ignores important opposing questions

An argument that uses authoritative testimony in a false manner

The argument relies on testimony of someone that is not an expert in the subject in question

The argument relies on the testimony of someone who is in expert in a relevant field but is biased due to the fact that they have a personal interest in the outcome of the argument

"Ignoring the question"

A deliberate attempt to divert the argument from the real question at hand

"Circular Reasoning"

An argument that restates one of its premises as the conclusion but provides no evidence that would lead one to infer the conclusion

An argument that provides little to no evidence for its claims

The conclusion usually:
-Rests on an inadequate number of instances
-Cites examples that are not typical or representative of the claim being made

A specific type of hasty generalization

Applies a valid principle or idea to a situation to a situation incorrectly

Occurs when a speaker fails to consider an overriding factor such as an extenuating circumstance, higher law or principle

A type of hasty generalization

AKA "data manipulation"

Using a statistic to support a conclusion without taking into account:
-the relevance of the statistic
-the way in which the statistic was derived
-other related statistics that might invalidate the argument

1. Fallacy of Accident
2. Misleading Statistic

Arguments that establish a cause-effect relationship that does not exist

1. Common cause fallacy
2. Post Hoc Ergo Propter Hoc Fallacy

AKA "Third Cause Fallacy"

Says that X causes Y when, in reality, both X and Y are caused by Z

Post hoc ergo propter hoc = After this, therefore because of this

Assumes that one event is the cause of another event simply because the first occurred before the second

Rejects a particular action on the grounds that it will inevitably lead to other, less desirable actions that are overstated

Fails to consider other actions that can be take to limit any further negative developments

AKA "either/or fallacy", "false choice fallacy" or "false dichotomy"

Argument that presupposes only two different possible options

Fails to recognize any middle ground or alternative positions

An argument that uses the same term in two different ways, or with two different meanings, so that the inference drawn in the conclusion is illogical

An assertion of line of reasoning that assumes that something is true about the whole of a group because if is true of its individual parts

An argument that assumes what is true of the whole is also true of the individual parts