Logic Exam 1

Fallacies

Argument

a sequence of statements in which it is claimed that one of the statements follows from the others.

Deductive Argument

An argument is deductive if and only if it is claimed that it is impossible for the conclusion to be false if all premises are true.

Inductive Argument

An argument is inductive if and only if it is claimed that it is improbable that the conclusion is false if all premises are true.

Valid Deductive Argument

A deductive argument is valid if and only if it is impossible for all the premises to be true but the conclusion false

Sound Deductive Argument

A deductive argument is sound if and only if it is valid and all of its premises are true

Strong inductive

is one where the conclusion is probably true, though not certain, if the premises all are true

Cogent

an inductive argument is cogent if it is strong and all premises are true

Formal Fallacies

are due to the logical structure or form of an argument. Even if the premises are true the conclusion does not need to follow due to a flaw in the form.

Informal Fallacies

are fallacies that cannot be defined in purely formal terms.

Affirming the consequent

where a statement is assumed to work in reverse but this doesn’t mean it’s always true.

Denying the antecedent

when a statement is followed by the denial of the antecedent leading to the invalid conclusion that the consequent must also be false.

appeal to the stick

occurs when someone threatens or uses intimidation to persuade others to accept a conclusion.

to the man

occurs when someone attacks the character or attribute of the person making the argument.

appeal to pity

occurs when someone attempt to persuade others to accept a conclusion based on pity rather than relevant evidence.

appeal to the people

tries to persuade by appeal to popular opinion or social acceptance.

from ignorance

assumes that a lack of evidence against a claim is evidence for it, or that a lack of evidence for a claim is evidence against it.

appeal to authority

appealing to an authority in an area that lies outside their competence.

accident

occurs when a general rule is wrongly applied to a specific case ignoring the fact that the particular case is an obvious exception to the general principle

hasty generalization

where someone draws a broad conclusion about a population based on a small example.

circular reasoning

occurs when an argument’s conclusion is assumed in its premises. When the argument goes in a circle without providing real support.

arguing beside the point

occurs when someone presents an argument that may be valid in itself but does not address the issue actually under discussion.

equivocation

using a word in two different senses within the same argument.

Collective sense

refers to a group or whole as a single entity

Distributive sense

refers to each individual member of the group

fallacy of composition

assuming that what is true in the distibutive sense is also true in the collective sense

fallacy of divsiion

assuming that what is true in the collective sense is also true in the distributive sense