I have started this new thread to address this issue.

In some of the threads here, roscoe has said that a negative cannot be proven.

From the thread, Engineering Analysis Of Why WTC Fell, he wrote...

"Planes hit the World Trade Centres they just weren't AA11 & UA175. Unless of course you can prove differently.

Anyone who answers this by asking me to prove a negative is an idiot. "

Roscoe, recent DNA evidence has proven, several times, that certain suspected criminals DID NOT commit crimes they were originally suspected and even convicted of.

This is just one example of proving a negative.

You can prove a negative by first establishing two statements that both cannot be true at the same time, then prove one to be true. The other must be false.

This only indicates that their DNA wasn't found, it does NOT prove that they didn't commit the crime.

The absence of their DNA does not prove anything.

I notice you used the word "indictes" rather than the word "proves." In other words, this only proves that their DNA wasn't found, it does NOT prove that they didn't commit the crime.

Or, to shorten that - it proves that their DNA was NOT found. Not. That's a negative.

I wont go into the issue of how valuable and trusted DNA evidence has been in exonerating wrongfully accused individuals.

Sure it does. It means that their DNA is NOT present. That's a negative.

But we don't have to stick with this example though.

How bout this. A man walks into a professional doctor's office for a physical exam. The doctor asks, "Are you a woman?" The man says,"no." Doctor says, "prove it."