
e corresponding truth table is shown in Table 3.9. e two premises of the argument, a → (c
→ b) and a → c, are arranged in Columns 5 and 6, respectively. e conclusion a → b is shown in
Column 7. In Rows 1, 2, 3, 4 and 8, both the premises are true. e corresponding truth-values of
the conclusion, noted in Column 7 are also true. Hence the argument is valid
Table 3.9. Consistency checking
(1) (2) (3) (4) (5) (6) (7)
ab b
c → ba → (c → b) a → ca → b
(1) 0 0 0 1 1 1 1
(2) 0 0 1 0 1 1 1
(3) 0 1 0 1 1 1 1
(4) 0 1 1 1 1 1 1
(5) 1 0 0 1 1 0 0
(6) 1 0 1 0 0 1 0
(7) 1 1 0 1 1 0 1
(8) 1 1 1 1 1 1 1
3.1.2 Predicate Logic
e propositional logic described above ...