Logic Terms – Part Two

Deductive Argument: An argument such that, IF it is “good” then it establishes its conclusion with certainty.

Inductive Argument: An argument such that, IF it is “good” then it establishes its conclusion as more likely.

Valid Argument: A deductive argument such that, IF the premises are true then the conclusion must be true.

Sound Argument: A valid deductive argument with all true premises.

Strong Argument: An inductive argument such that, IF the premises are true then the conclusion is likely. (Unlike validity, inductive strength is a matter of degree.)

Cogent Argument: A strong inductive argument with all true premises.

►When analyzing any argument we want to know the answer to two distinct questions: 1. Do the premises support the conclusion in the right way?; and 2. Are all the premises actually true? If the argument is deductive and the answer to the first question is “yes,” then we say that it’s “valid” – if not, then it’s “invalid.” If an argument is valid and all of its premises are true then we say it’s “sound” – if not, then it’s “unsound.” All invalid arguments are unsound. If the argument is inductive and the answer to the first question above is “yes,” then we say it’s “strong” – if not, then it’s “weak.” If an argument is strong and all of its premises are true then we say it’s “cogent” if not, then it’s “uncogent.” And again, all weak arguments are uncogent.