Investigators have not proved that the forest fire was started by campers. Nor have they proved that lightning trigge...

Kyle on May 29, 2016

What is the flaw?

I identified the correct answer because it matches the reasoning in the stimulus, but I'm having trouble identifying just what the flaw is in the argument. From where I sit, I see the following: P1: "have not proved that the forest fire was started by campers." P2: "Nor have they proved that lightning triggered the fire." C: "Investigators have not proved that the blaze was caused by campers or lightning" This seems to me like a valid argument. It's not saying that it's impossible that either (or both) group did start the fire. It is not even saying that investigators never will prove that one or the other (or both) started the fire. It is simply saying that, at this present point in time, neither has been proven to have started the fire...which seems to me to be completely supported by the premises. Please assist, thanks.

1 Reply

Kyle on May 29, 2016

Ok - after an hour of going though (mostly) unhelpful explanations online, I think I have it.

Reworded argument:

I haven't proven campers did it. I haven't proven lightning did it. Thus, I haven't proven lightning or campers did it.

Here is the flaw. Just because I do not yet have sufficient evidence to conclusively prove that either one caused the fire does NOT mean that I do not have sufficient evidence to prove that the fire was definitely caused by either the campers or lightning.

In other words, I may have investigated the fire, eliminated thousands of possibilities, and conclusively proven that it could have only been started by either campers or lightning. I just don't know which yet.