Logic and Truth

Rindang P. 121012173

• The study of logic Classical Greek world ( Aristotle )

• Logic the principle of valid argument and inference

• Tools of logic help to represent sentence meaning

The example of Aristotle’s modus ponen (a type of argument in 3 steps)

If step a & b are TRUE, so step c is also TRUE

a. If Mark is not in the bar, then he is in the lounge.

Modus Ponenb. Mark is not in the bar.

c. Mark is in the lounge.

premises

conclusion

• Part of this study is concern for truth of statements and whether truth is preserved or lost by putting sentence into different patterns.

• Truth correspondence with facts• Most part of this truth

empirical/contingent

• The example of the truth or otherwise of sentence :

My father was the first man to visit Mars.*depend on facts, if the fact is true, the sentence is true, otherwise is false.

• The example of empirical truth :The earth revolves around the sun.

*depend upon the facts of the universeSemantistics call sentence’s being TRUE or FALSE

as truth value and call the facts as truth condition.

• By adding NOT, it will REVERSE its truth valueExample : a. Your car has been stolen.

b. Your car has not been stolen.If a is TRUE, b is FALSE. If a is FALSE, b is TRUE.

• Logicians use a schema, logical form, where a lower case letter (p,q,r,etc) stands for the statements and special symbol for negation : -.

THUS, Your car has been stolen pYour car has not been stolen. -p

THUS, Your car has been stolen pYour car has not been stolen. -pThe effect of negation (-) on truth value of

statement can be shown by a truth table, where T “true”

F “false”