Thursday, February 8, 2001
A judgment is objective if its outcome does not depend on the judge; taste of coffee vs. validity of argument. (Lecture).
An argument is formal if the validity of the argument does not depend on the meaning of the symbols employed. (Handout #5).
From the assumption `not A' and the derivation of a contradiction you
infer `A'. (Lecture)
From the assumption `not A' and the derivation of a contradiction you infer `A'. (Lecture)
You know nothing, the argument could as well be invalid. (Lecture)
The argument is not valid. Because it is possible for the premises to be true, but the conclusion to be false, for example, if my income rises because of a raise and not because of the lowering of my taxes. (Lecture)