In the last two pages we have been distinguishing between the two kinds of argument. There are two kinds of inferential claim that can be made: absolute and probabilistic. Arguments which make the absolute claim are called deductive. Arguments which make the weaker probabilistic claim are called inductive. If the inferential claim of a deductive argument is correct, we say the argument is valid. If the claim is incorrect, we say the argument is invalid. Deductive arguments are either valid or invalid. There is no in between. If the truth of the premises makes it impossible for the conclusion to be false, the argument is valid . If it is possible for the conclusion to be false, then the argument is invalid.
The case of inductive arguments is a bit more complex. Inductive arguments don't make the claim that the premise absolutely makes the conclusion true. They make the more guarded claim that the truth of the premises makes the conclusion likely to be true. So inductive arguments differ in the degree of support given to their conclusions. So inductive arguments range from very strong to very weak with many grades in between. Another difference between deductive and inductive arguments is that deductive arguments stand independently of everything else. If a deductive argument is valid no new facts could ever make it invalid. But with inductive arguments the strength or weakness of the argument can vary with additional facts that come to our consideration. Since the strength of inductive arguments is a matter of degree new facts can make a weak inductive argument stronger or a strong inductive argument weaker.