Chapter 1 Basic Concepts Flashcards
To understand the basic concepts of Formal Logic
Logic
the study of methods for evaluating whether the premises of an argument adequately support its conclusion
Argument
a set of statements that support eachother
Statement
sentence that is either true or false
Deductive Argument
one in which the premises aim to guarantee the conclusion
Inductive Argument
one in which the premises aim to make the conclusion probable
Valid Argument
one in which it is necessary that, if the premises are true, then the conclusion is true
Invalid Argument
one in which it is not necessary that, if the premises are true, the conclusion is true
Sound Argument
a valid argument in which all of the premises are true
Unsound Argument
one that either is invalid or has at least one fals premise
Modus Ponens
1) if A, then B 2) A So, 3) B
Modus Tollens
1) if A, then B 2) Not B So, 3) Not A
Hypothetical Syllogism
1) if A, then B 2) if B, then C 3) C So, 4) if A, then C
Disjunctive Syllogism
1) Either A or B 2) Not A So, 3) Not B
Constructive Dilemma
1) Either A or B 2) if A, then C 3) if B then D So, 4) Either C or D
Argument Form
a pattern of reasoning
Substitution Instance
an argument that results from uniformly replacing variables in that form with statements
Valid Argument Form
one in which every substitution instance is a valid argument
Formally Valid Argument
one that is valid by virtue of its form
Negation
the negation of a statement is its denial
Conditional
an “if-then” statement”
Antecedent
the “if”-clause of a conditional
Consequent
the “then”-clause of a conditional
Disjunct
an either-or statement
Fallacy of Denying the Antecedent
1) if A then B 2) not A So, 3) Not B
Fallacy of Affirming the Consequent
1) if A then B 2) B So, 3) A
Categorical Statement
a statement that relates two classes or categories, where a class is a set or a collection of things
Term
word or a phrase that stands for a class of things
Some
“at least one”
Good Counterexample
substitution instance in which the premises are well-known truths and the conclusion is a well-known falsehood
Invalid Argument Form
one that has some invalid substitution instances
Strong Argument
one in which it is probable (but not necessary) that, if the premises is true, then the conclusion is true
Weak Argument
one in which it is not probable that, if the premises are true, then the conclusion is true