I hate to be the nerd here, but the entire thread labelled deductive reasoning on the discussion forum is really about inductive reasoning, which is often a faulty exercise.

Deductive reasoning is generally very sound (as long as the major premise and minor premise are valid). Deductive reasoning follows a major premise, minor premise, conclusion pattern (Like the classic: All men are mortal, CJR is a man, thus CJR is mortal).