Definitions

Question 1

Logic

Answer 1

The study of methods for evaluating whether the premises of an argument adequately support its conclusion.

Question 2

argument

Answer 2

A set of statements where some of the statements, called the premises, are intended to support another, called the conclusion.

Question 3

statement

Answer 3

a sentence that is either true or false.

Question 4

deductive argument

Answer 4

an argument in which the premises are intended to guarantee the conclusion.

Question 5

inductive argument

Answer 5

an argument in which the premises are intended to make the conclusion probable, without guaranteeing it.

Question 6

valid argument

Answer 6

an argument in which it is necessary that, if the premises are true, then the conclusion is true

Question 7

invalid argument

Answer 7

an argument in which it is not necessary that, if the premises are true, then the conclusion is true.

Question 8

sound argument

Answer 8

a valid argument in which all of the premises are true.

Question 9

unsound argument

Answer 9

an argument that either is invalid or has at least one false premise.

Question 10

argument form

Answer 10

a pattern of reasoning.

Question 11

substitution instance

Answer 11

an argument that results from uniformly replacing the variables in that form with statements (or terms)

Question 12

valid argument form

Answer 12

an argument form in which every substitution instance is a valid argument.

Question 13

formally valid argument

Answer 13

an argument that is valid in virtue of its form.

Question 14

negation

Answer 14

the negation of a statement is its denial.

Question 15

conditional statement

Answer 15

an if-then statement, often simply called a “conditional.”

Question 16

antecedent

Answer 16

the if-clause of a conditional.

Question 17

consequent

Answer 17

the then-clause of a conditional.

Question 18

disjunction

Answer 18

an either-or statement.

Question 19

disjuncts

Answer 19

the statements that make up a disjunction.

Question 20

fallacy of denying the antecedent

Answer 20

an invalid argument form: If A, then B; not A; so, not B.

Question 21

invalid argument form

Answer 21

one that has some invalid substitution instances

Question 22

counterexample

Answer 22

a counterexample to an argument form is a substitution instance in which the premises are true and the conclusion is false.

Question 23

good counterexample

Answer 23

a good counterexample to an argument form is a substitution instance in which the premises are well-known truths and the conclusion is a well-known falsehood.

Question 24

fallacy of affirming the consequent

Answer 24

an invalid argument form: If A, then B; B; so, A.

Question 25

categorical statement

Answer 25

a statement that relates two classes or categories, where a class is a set or collection of things.

Question 26

term

Answer 26

a word or phrase that stands for a class of things.

Question 27

conjunction

Answer 27

an “and” statement

Question 28

excess verbiage

Answer 28

a word or statement that adds nothing to the argument.

Question 29

discount

Answer 29

an acknowledgment of a fact or possibility that might be thought to render the argument invalid, weak, unsound, or uncogent.

Question 30

repetition

Answer 30

a restatement of a premise or conclusion, perhaps with a slightly altered wording.

Question 31

assurance

Answer 31

a statement, word, or phrase that indicates the author is confident of a premise or inference.

Question 32

hedge

Answer 32

a statement, word, or phrase that indicates that the author is confident of a premise or inference.

Question 33

enthymeme

Answer 33

an argument with an implicit premise or conclusion.

Question 34

atomic statement

Answer 34

one that does not have any other statement as a component.

Question 35

compound statement

Answer 35

one that has at least one atomic statement as a component.

Question 36

main logical opoerator

Answer 36

a compound statement is the one that governs the largest component or components of a compound statement.

Question 37

minor logical operator

Answer 37

an operator that governs smaller components.

Question 38

well-formed formula

Answer 38

(WFF) is a grammatically correct symbolic expression.

Question 39

conjuncts

Answer 39

the statements composing a conjunction.

Question 40

logical equivalence

Answer 40

two statements are logically equivalent if and only if they agree in truth value on every assignment of truth values to their atomic components.

Question 41

statement variable

Answer 41

a lowercase letter that serves as a placeholder for any statement - for example, p, q, r, s.

Question 42

truth-functional

Answer 42

a compound statement is truth-functional if its truth value is completely determined by the truth value of the atomic statements that compose it.

Question 43

material conditional

Answer 43

a conditional that is false only when its antecedent is true and its consequent is false; otherwise, it is true.

Question 44

material biconditional

Answer 44

a conjunction of two material conditionals; it is true when its constituent statements have the same truth value and false when they differ in truth value.

Question 45

tautology

Answer 45

a statement is a tautology if and only if it is true on every assignment of truth values to its atomic components.

Question 46

contradiction

Answer 46

a statement is a contradiction if and only if it is false on every assignment of truth values to its atomic components.

Question 47

contingent statement

Answer 47

a statement is contingent if and only if it is true on some assignments of truth values to its atomic components and false on others.