PHIL 150 Chapter Notes - Chapter 7, E-F: Baltimore Stars
10 May 2018
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PHIL Logic Reading Notes
Chapter 7 (E-F)
E. Contingent and Noncontingent Statements
x Contingent statements: statements that are neither necessarily true nor necessarily false
o The truth values of the proposition are contingent on the truth values of the component
parts
x Noncontingent statements: statements such that the truth values in the main operator column do
not depend on the truth values of the component parts
o Two kinds of noncontingent statements: tautologies and self-contradictions
x Tautology: a statement that is necessarily true
x Self-Contradiction: a statement that is necessarily false
F. Logical Equivalence and Contradictory, Consistent, and Inconsistent Statements
x Logically equivalent: two truth-functional statements that have identical truth tables under the
main operator
x Contradictory statements: two statements that have opposite truth values under the main
operator on every line of their respective truth tables
x Consistent statements: two (or more) statements that have at least one line on their respective
truth tables where the main operators are true
x Inconsistent statements: two (or more) statements that do not have even one line on their
respective truth tables where the main operators are true (but they can be false) at the same time
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