Posted by Barney on January 03, 2003

In Reply to: Negative phrase posted by R. Berg on January 03, 2003

: : Explain the meaning the of the phrase: "you can't prove a negative." What does it mean, and how can you use it, and where does it come from?

: From the study of logic. If I assert that there are no casserole recipes that include vinegar, I have said something I can't prove, because it's always possible that somebody will find one recipe like that and prove me wrong. The principle applies only to certain kinds of negative statements. It doesn't apply to the statement "I don't have a gallon of blue paint in my pants pocket." I can prove that one by turning the pocket inside out.

Another good example is in asking Iraq to prove that it has no weapons of mass destruction.